The Messenger

No. 147 – March 2012 Progress on MUSE on Progress Search intermediate-mass for black holes survey spectroscopic public Gaia-ESO The galaxies teenage of survey MASSIV The Telescopes and Instrumentation

High-speed Bandwidth between Europe and Paranal: EVALSO Demonstration Activities and Integration into Operations

Fernando Comerón1 Operation in such a distributed environ- EVALSO demonstration activities Jim Emerson 2 ment involves the intercontinental transfer Konrad Kuijken 3 of a wide variety of data, most notably The recently completed EVALSO infra- Stefano Zampieri1 (although certainly not only) the large vol- structure is the definitive step in over Andrew Wright1 ume of science and calibration data pro- coming these limitations for the current Giorgio Filippi1 duced by the instruments each night. The facilities on Paranal, including the survey data obtained are quickly controlled for telescopes and the second generation quality and used in a sophisticated instru- instrumentation to become available 1 ESO ment health-check process, taking place in the near future. EVALSO (for Enabling 2 Astronomy Unit, Queen Mary University offline in Garching, which ensures that Virtual Access to Latin-American South- of London, United Kingdom instruments are kept in optimal operating ern Observatories) is a consortium of nine 3 Leiden Observatory, the Netherlands condition at all times. The immediate organisations partly funded by the Euro- availability of data through the ESO pean Union under its seventh Framework archive, which is also physically located Programme (FP7) with the goal of set- A substantial improvement in the con- in Garching, currently enables authenti- ting up a high-bandwidth communica- nectivity between the Paranal Observa- cated users to download their proprietary tions infrastructure between Europe and tory and ESO Headquarters has been data as soon as the data are ingested the observatories of Paranal and Cerro recently made with the completion into the archive, typically a few hours or Armazones, the latter operated by the of the FP7-funded EVALSO project and less after acquisition. Ruhr-Universität Bochum. A description its integration into the operational infor- of the project, the overall infrastructure, mation and communications technology The successful implementation of these its technical implementation and the list of the observatory. Here we describe features requires the availability of suf of participants has been provided in a the demonstration of capabilities, car- ficient bandwidth for the intercontinental previous article in The Messenger (Filippi, ried out as the final part of the project; transfer of the data stream. In the first 2010), and further information is available some expected applications in the ten years of VLT operations, the combi- on the web1. short term; and the possibilities that are nation of bandwidth costs and the fast opened up by the availability of such growth of data production on Paranal As part of the FP7 project, EVALSO in high-bandwidth communication links. required the transfer of data to Garching cluded a number of Joint Research to take place through physical media Activities with the purpose of demon- (disks), introducing a delay of one to two strating the scientific value of the new Transferring data between Paranal and weeks between the acquisition of the infrastructure. One of these activities Garching data and their ingestion in the archive. exploited the capabilities of EVALSO to This delay effectively decoupled the day- establish a virtual presence system at The end-to-end operations model of to-day operation of the observatory the observatory of Cerro Armazones, the ESO facilities on Paranal takes place from the detailed quality control process while the other two tested the data trans- in a geographically distributed environ- taking place in Europe. A major break- fer capabilities between Paranal and ment, with different parts of the lifecycle through took place in 2008 with the Europe and the potential of the new link of observing programmes taking place implementation of the transfer of the VLT for remotely performing observations either in Garching or at the observatory data stream over the internet (Zampieri from a European institute with sufficient site. Most users of ESO facilities, either et al., 2009), which reduced the time bandwidth. directly through the submission and exe- lag between acquisition and ingestion cution of observing programmes, or into the archive to a few hours at most. The VISTA/VIRCAM data stream, averag- through the use of archive data, are al Besides allowing end users to access ing approximately 50 GB (compressed) ready familiar with different components their data much faster, shortening the per night, was sent through the EVALSO of this model, which was initially imple- operations duty cycle also brought signifi- link for four months, with a measured, mented at the New Technology Tele- cant improvements in the quality control sustained Paranal–Garching transfer rate scope (NTT) in 1997, and extended to the process. However, the available band- of 9 MB/s. This rate represents a tenfold Very Large Telescope (VLT) when it width was far from allowing remote near- increase in capacity over that available began operation in 1999. The model has real-time access to Paranal data, and until now, making possible the transfer of evolved substantially since then. The lat- was not sufficient to handle the increase a typical full night of VIRCAM data (the est additions to the Paranal Observatory, in data production when VISTA, and more instrument currently dominating the data the survey telescopes, VISTA and the recently the VST, began operations, and stream from Paranal) in less than two VST, have been integrated into this model at the outset their data still needed to be hours, and demonstrates the feasibility of since they began regular operations, and shipped to Garching in disks. transferring the entire Paranal data stream, the Atacama Pathfinder Experiment including the VLT, the VLTI (VLT Interfer- (APEX) and the Atacama Large Millimeter/ ometer), VISTA and the VST, in less than submillimeter Array (ALMA) science oper- 24 hours (Romaniello et al., 2011). Given ations also share many of its features. the currently available high bandwidth

2 The Messenger 147 – March 2012 between ESO and the Cambridge Astro- and Paranal Science Operations staff. operating regularly in mid-February 2012, nomical Survey Unit (CASU) in the UK, Both raw and pipeline-processed data with the whole of the VLT/VLTI data where full pipeline processing of all data reaching a staging area in Garching were stream and all the VST calibration frames obtained with VIRCAM is routinely carried retrieved by the user via ftp, and, follow- being routed through it. VISTA and the out, this will open up the possibility of a ing a quick analysis of the pipeline- rest of the VST data stream will be added significantly faster turnaround time in the processed data, the OBs were modified shortly after, following some optimisation processing of VIRCAM data in Cambridge and resubmitted for execution. This was to be done on the science data transfer in the future. The flow has been limited intended to reproduce the experience software (Zampieri et al., 2009). until now by the time spent in the inter- of a future remote user interacting with continental transfer of the hard disks con- the observatory mainly through the sub- The data transfer capabilities offered taining the data. mission of OBs, and being able to modify by EVALSO are already sufficient to sig- them in reaction to the results just ob nificantly improve end-to-end operations The test configuration of EVALSO was tained in the preceding observation. by ensuring that the current backend also intensively used during the com Thanks to the availability of the EVALSO operations procedures applied to the missioning of OmegaCAM, as noted by link the observing efficiency approached VLT/VLTI data stream thus far can be Kuijken (2011). The use of EVALSO on that of a visiting astronomer carrying extended to the entire data stream from the commissioning of this instrument out a similar programme from the control all the facilities on Paranal, including clearly illustrated some of the advantages room at the observatory, although the the full set of VLT and VLTI second gen- of the new high bandwidth capabilities. results also highlighted the need for addi- eration instruments as they become It allowed remotely located members of tional tools and upgrades of existing operational. The performance is expected the commissioning team to participate ones, as well as other changes in the VLT to further improve through the optimisa- in the analysis of the observations shortly operations model, to efficiently enable a tion of the data transfer software and the after they were obtained, on nearly the possible remote observing mode by reg- expanded capabilities of the transoce- same timescale as the commissioning ular users of ESO facilities in the future. anic link provided by the upgrades of team working at Paranal, which, given ALICE2. This research infrastructure was the very high data volumes, would have created with EU support in 2003 for been impossible without EVALSO. The Integration of EVALSO into operations the establishment of high-capacity inter- EVALSO link has also been used in its connectivity within South America and test configuration to support the backend Following the successful verification of transatlantic connection to European of the OmegaCAM data flow, making the the new capabilities offered by the National Research Networks. The high data obtained with this instrument availa- EVALSO infrastructure, ESO proceeded bandwidth connectivity with the observable for detailed quality control and health towards integrating it into the operations tory provided by EVALSO will in this checking in Garching on the day follow- network of the observatory, which was way open new possibilities, such as a vir- ing the night when the observations were completed in mid-December 2011 and is tual presence at the observatory and obtained. expected to become fully functional in a possible implementation of additional mid-February 2012. The link from Santi- observing modes in future VLT operations. Tests on the feasibility of EVALSO to sup- ago to Garching is now handled by dual port VLT observations in remote mode VPN tunnels, one over a link supplied by were also successfully carried out in May a commercial provider, and the other by References and June 2011. Most of the tests were REUNA/RedClara, the Chilean NREN that Filippi, G. 2010, The Messenger, 142, 2 conducted from Garching using a Linux is one of the EVALSO partners (see Fig- Kuijken, K. 2011, The Messenger, 146, 8 laptop equipped with a user installation ure 1 of Filippi [2010] for more detail). The Romaniello, M. et al. 2011, SPIE, 7737, 53 of the Phase 2 Proposal Preparation passing of traffic over the links is config- Zampieri, S. et al. 2009, ASP Conf. Ser., 411, 540 (P2PP) tool, as well as standard software ured using policy-based routing and for astronomical data analysis, including access control lists to determine the path Links IRAF and the Skycat tool. One set of to be taken for each traffic type, with sci- tests was carried out by a user located at entific data regularly taking the REUNA/ 1 EVALSO web page: http://www.evalso.eu the Vatican Observatory in Italy, to verify RedClara link. The same configuration is the feasibility from other locations in applied at Paranal, with the EVALSO link Europe connected to their corresponding being used for the transfer of EVALSO National Research and Education Net- data. works (NREN). The functionality of the EVALSO/REUNA The test observations consisted of the link has also been verified by the transfer execution on Paranal of Observing to Garching of scientific data obtained Blocks (OBs) prepared by the user while from La Silla, which has worked flawlessly keeping a direct voice channel to since mid-January 2012. The Paranal exchange information between the user transfer through the EVALSO link will start

The Messenger 147 – March 2012 3 Telescopes and Instrumentation

News of the MUSE

Roland Bacon1 Alban Remillieux1 measuring capabilities of a high-quality Matteo Accardo4 Edgar Renault1 spectrograph, while taking advantage Louisa Adjali1 Petra Rhode 5 of the increased spatial resolution pro- Heiko Anwand 5 Johan Richard1 vided by adaptive optics. MUSE also has Svend-Marian Bauer 2 Martin Roth 2 a high spatial resolution mode with a Jeremy Blaizot1 Gero Rupprecht 4 7.5 × 7.5 arcsecond field of view sampled Didier Boudon1 Joop Schaye7 at 25 milliarcseconds. In this mode Jarle Brinchmann7 Eric Slezak 9 MUSE should be able to obtain diffrac- Loic Brotons1 Genevieve Soucail6 tion-limited datacubes in the 0.6–0.93 µm Patrick Caillier1 Matthias Steinmetz 2 wavelength range. Lionel Capoani1 Ole Streicher 2 Marcella Carollo 3 Remko Stuik7 MUSE has been presented in Bacon et Mauro Comin4 Hervé Valentin 6 al. (2006). At that time the project was Thierry Contini 6 Joël Vernet 4 in an early stage (preliminary design Claudio Cumani4 Peter Weilbacher 2 phase). Meanwhile the concept has trans- Eric Daguisé1 Lutz Wisotzki 2 formed into an impressive piece of hard- Sebastian Deiries4 Nathalie Yerle 6 ware. MUSE is now entering its very final Bernard Delabre4 Gérard Zins 8 phase of integration, testing and valida- Stefan Dreizler 5 tion in Europe. Jean-Pierre Dubois1 Michel Dupieux 6 1 CRAL, Observatoire de Lyon, The MUSE hardware is composed of 24 Christophe Dupuy 4 Saint-Genis-Laval, France identical modules, each consisting of Eric Emsellem4 2 Leibniz Institute für Astrophysik an advanced slicer, a spectrograph and Andreas Fleischmann5 Potsdam, AIP, Germany a 4k × 4k pixel detector. A series of fore- Mylène François1 3 Institute of Astronomy, ETH Zentrum, optics and splitting and relay optics dero- Gérard Gallou 6 Zurich, Switzerland tates and partitions the square field of Thierry Gharsa6 4 ESO view into 24 sub-fields. These optics sys- Nathalie Girard6 5 Institute for Astrophysics Göttingen, tems will be placed on the Nasmyth Andreas Glindemann4 Germany platform between the VLT Nasmyth focal Bruno Guiderdoni1 6 IRAP, Observatoire Midi Pyrénées, plane and the 24 integral field unit (IFU) Thomas Hahn 2 Toulouse, France modules. Ghaouti Hansali1 7 NOVA, Sterrewachte Leiden, Denis Hofmann 5 the Netherlands Aurélien Jarno1 8 IPAG, Observatoire de Grenoble, France Instrument innovations Andreas Kelz2 9 Observatoire de Nice, France Mario Kiekebusch4 Among the numerous technical innova- Jens Knudstrup4 tions utilised in the instrument it is worth Christof Koehler 5 We report on progress of the Multi Unit mentioning a few important achieve- Wolfram Kollatschny 5 Spectroscopic Explorer (MUSE), a ments. Johan Kosmalski1 second generation VLT panoramic inte- Florence Laurent 1 gral field spectrograph. MUSE is now The slicer, a key element of the project, is Marie Le Floch 6 in its final phase of integration, testing a compact stack of spherical off-axis Simon Lilly 3 and validation in Europe. The instru- two-mirror systems. Each slicer incorpo- Jean-Louis Lizon à L’Allemand4 ment is described and some results of rates an array of 48 thin slices, which Magali Loupias1 its measured performance are shown. are assembled with a very high precision, Antonio Manescau4 and kept in place by optical contacting. Christian Monstein 3 This array faces another array of 48 small Harald Nicklas5 The Multi Unit Spectroscopic Explorer off-axis spherical pupil mirrors. The sys- Jens Niemeyer 5 (MUSE) is a second generation Very tem rearranges the input image geometri- Jean-Christophe Olaya 2 Large Telescope (VLT) panoramic integral cally into 48 small pseudo-slits with only Ralf Palsa4 field spectrograph. MUSE has a field two optical reflections. This guarantees Laurent Parès6 of 1 × 1 arcminutes, sampled at 0.2 × 0.2 the highest possible throughput. The pro- Luca Pasquini 4 arcseconds and is assisted by the VLT duction of the 24 slicers, i.e., 2304 high Arlette Pécontal-Rousset1 ground layer adaptive optics facility using precision optical elements, has been Roser Pello 6 four laser guide stars (Arsenault et al., contracted to Winlight Optics. In January Chantal Petit1 2010). The simultaneous spectral range is 2012, they delivered 23 slicers and the Laure Piqueras1 0.465–0.93 µm, at a spectral resolution remaining one is expected very soon. It Emile Popow 2 of ~ 3000. MUSE couples the discovery took a significant time to fine tune the Roland Reiss4 potential of a large imaging device to the industrial production and alignment pro-

4 The Messenger 147 – March 2012 Figure 1. One of MUSE’s slicer image dissectors and the focusing mirror arrays are shown before assembly in the laboratory.

Figure 2. IFU technical first light image. This image cesses, but today all the slicers we have constitutes one integral field unit. The shows the first exposure of a complete IFU obtained in the laboratory. This picture was obtained by in hand achieve very high performance. system is then aligned and qualified. The exposing the IFU to a set of neon, xenon and mer- Figure 1 shows one of the assembled performance of each IFU is carefully cury–cadmium arc lamps for a few seconds. Part of slicers. checked and monitored. The IFU point the image is zoomed to display the arc lamp emis- spread function is a major contributor sion lines produced by six slices in more detail. Each slicer is located at the entrance of to the overall image quality budget and a spectrograph. The 24 spectrographs determines the final spectral performance. to the wavelength of light hitting each have a compact design and incorporate We are pleased to report that the IFUs pixel of the detector. This gives a signifi- a wide spectral range volume phase achieve a very high and homogeneous cant boost to the quantum efficiency and holographic (VPH) grating specifically de image quality, even better than the origi- reduces the fringing. All the CCDs have signed for MUSE by Kaiser Optical Sys- nal specifications, which were already been mounted in their detector heads, tems. Winlight is also in charge of spec- considered as tight. Figure 2 shows the and have been characterised by the opti- trograph production, and has delivered first image of an exposure of an arc lamp. cal detector team at ESO, and found 19 units so far. After alignment, the slicer to be within specification. As proper align- is attached to the front part of the spec- Each detector vessel incorporates one trograph, while the detector vessel 4k × 4k 15 µm deep depletion CCD connects to the rear side. This assembly device with improved quantum efficiency Figure 4. Front view of MUSE in the CRAL integra- in the red wavelength range. The com- tion hall. The two electronics cabinets (one for the Figure 3. Rear view of MUSE in the CRAL integration pany e2v delivered 26 top quality detec- cooling system, the other for the fore-optics and cal- hall, showing the large cryogenic system in charge tors to ESO. These detectors implement ibration unit mechanism and lamps) can be seen in of cooling and vacuum control for the 24 cryostats. the foreground. The front part of the fore-optics is The large IFU holes in the main structure are visible an innovative graded index anti-reflection visible at the top of the main structure. It faces an between the cooling cables. coating, which is optimised according optical system which simulates the VLT light beam.

The Messenger 147 – March 2012 5 Telescopes and Instrumentation Bacon R. et al., News of the MUSE

Figure 5. First IFU inser- scenes have started and demonstrate tion. One complete IFU that the system is able to handle the huge is visible before its insertion into the main struc- data volume provided by the instrument. ture. A dedicated tool (in yellow) has been built We are now proceeding to align and to ease the insertion assess the performance of the 24 chan- while minimising the risk of damaging the delicate nels, in parallel with the alignment of image slicer, located in the remaining IFUs. The global tests and the front of the IFU, or performance verification will be con- the cables of the cooling cluded by the preliminary acceptance system. review in Europe (PAE), which is expected in October this year. The instrument will then be sent to Paranal for the re- integration and commissioning phase. This period is expected to take a significant fraction of 2013.

Prospects 80-layer dielectric coating from Balzers Optics. The solution was extensively With its 400 megapixels per frame and tested for durability under severe con- 90 000 spectra in one exposure, MUSE straints: humidity, temperature change is already the largest integral field spec- and scratch. The stress induced by the trograph ever built. The performance optical coatings on the substrates was measured in the laboratory demonstrates also checked and found to be tolerable. that it should also meet its very ambitious specifications on the telescope. In some critical areas such as image qual- Integration at CRAL ity and throughput it is even better than the original specifications. Once installed Early in 2011, ESO finalised the construc- at the Nasmyth focus of the VLT’s Unit tion of the impressive vacuum and cryo- Telescope 4, MUSE will immediately pro-

genic system, based on liquid N2 continu- vide the ESO community with a unique ous flow cryostats, and its control and powerful tool to address key scien- electronics, and delivered it to CRAL in tific questions in a large number of astro- Lyon. It was followed a few months later physical fields. A year later MUSE will by the equally impressive MUSE main be coupled to the Adaptive Optics Facility structure from IAG, the fore-optics sub- (Arsenault et al., 2010) using the GALACSI system from IRAP, and the calibration unit adaptive optics module. The expected from AIP. Figure 3 shows a rear view of spectacular gain achieved in spatial reso- the main structure and Figure 4 a view lution without any loss in throughput and from the front. The pieces were put with almost full sky coverage will boost Figure 6. The fore-optics system attached to the together and a first IFU inserted (see Fig- the MUSE performance by another sub- integration hall crane can be seen before its descent ures 5 and 6). A first set of mirrors and stantial factor. onto the main structure. lenses of the splitting and relay optics has been aligned such that we obtained first ment of the detector with respect to the light in late December, involving a full opti- References spectrograph is critical, the 24 completed cal path, from the calibration unit to the Arsenault, R. et al. 2010, The Messenger, 142, 12 detector heads have been systematically detector plane. Fine alignment is in pro- Bacon, R. et al. 2006, The Messenger, 124, 5 checked at AIP in Potsdam using a single gress, but we can already confirm the reference spectrograph. excellent image quality of the system; a wonderful Christmas gift. Links To improve further the total efficiency MUSE public website: http://muse.univ-lyon1.fr of the instrument, we have replaced In parallel to the visible hardware assem- the protected enhanced silver coating bly, a lot of effort has gone into the con- originally envisioned for the seven mir- trol and data reduction software. Full- rors of the optical train by a dedicated scale tests with simulated astrophysical

6 The Messenger 147 – March 2012 Telescopes and Instrumentation

APEX–SZ: The Atacama Pathfinder EXperiment Sunyaev–Zel’dovich Instrument

Daniel Schwan1 9 Materials Sciences Division, phenomena in great detail, for example, Rüdiger Kneissl2, 3 Lawrence Berkeley National Labo cluster formation and dynamics, cluster Peter Ade4 ratory, Berkeley, USA mergers and their associated shock Kaustuv Basu 5 10 Department of Physics, McGill waves (which are sites of cosmic ray Amy Bender 6 University, Montreal, Canada acceleration), the cosmic ratio of dark Frank Bertoldi 5 11 Department of Physics, University of matter to baryonic matter density, active Hans Böhringer7 Colorado, Boulder, USA galactic nuclei feedback, the evolution of Hsaio-Mei Cho 8 12 Department of Earth and Space galaxies in the ICM, heat transport pro- Gayoung Chon7 Sciences, Onsala Space Observatory, cesses, and plasma instabilities (Sarazin, John Clarke1, 9 Chalmers University of Technology, 1988). Matt Dobbs10 Sweden Daniel Ferrusca1 13 Department of Physics, Columbia In addition, galaxy clusters offer a unique Daniel Flanigan1 University, New York, USA probe into the composition and evolu- Nils Halverson 6,11 14 Physics Division, Lawrence Berkeley tion of the Universe. They are the most William Holzapfel1 National Laboratory, Berkeley, USA massive gravitationally-collapsed objects Cathy Horellou12 15 Max-Planck-Institut für Radioastro and directly map large-scale structure Daniel Johansson12 nomie, Bonn, Germany over a large range of redshifts. Conse- Bradley Johnson1,13 16 I. Physikalisches Institut, Universität zu quently, measuring the evolution of the James Kennedy10 Köln, Germany cluster number density places powerful Zigmund Kermish1 constraints on the parameters that Matthias Klein 5 govern the growth of structure. These Trevor Lanting10 The APEX–SZ instrument was a milli parameters are, notably, the mass energy Adrian Lee1,14 metre-wave (150 GHz) cryogenic re density and dark energy density of Martin Lueker1 ceiver for the APEX telescope designed the Universe, the dark energy equation of Jared Mehl1 to observe galaxy clusters via the state, and the matter power spectrum Karl Menten15 Sunyaev–Zel’dovich Effect (SZE). The normalisation (Carlstrom et al., 2002). Dirk Muders15 receiver contained a focal plane of Florian Pacaud 5 280 superconducting transition-edge The hot ICM is observable at millimetre- Thomas Plagge1 sensor bolometers equipped with a wavelengths via the SZE (Sunyaev & Christian Reichardt1 frequency-domain-multiplexed readout Zel’dovich, 1970). In the SZE, about 1% Paul Richards1 system, and it played a key role in the of cosmic microwave background (CMB) Reinhold Schaaf 5 introduction of these new, robust, and photons incident on the cluster are Peter Schilke16 scalable technologies. With 1-arcminute scattered by free intracluster electrons. Martin Sommer 5,15 resolution, the instrument had a higher The resulting signal distorts the CMB Helmuth Spieler 14 instantaneous sensitivity and covered a blackbody spectrum and is visible as a Carole Tucker 4 larger field of view (22 arcminutes) than temperature decrement (increment) at Axel Weiss15 earlier generations of SZE instruments. frequencies below (above) 217 GHz. The Benjamin Westbrook1 During its period of operation from 2007 SZE surface brightness is proportional Oliver Zahn1 to 2010, APEX–SZ was used to image to the integrated gas pressure along the over 40 clusters and map fields overlap- line of sight through the cluster. Since ping with external datasets. This paper the SZE is a scattering effect seen rela- 1 Department of Physics, University of briefly describes the instrument and tive to the CMB, and the scattered and California, Berkeley, USA data reduction procedure and presents unscattered photons are redshifted 2 ESO a cluster image gallery, as well as results together, the SZE signal is independent 3 Joint ALMA Observatory, Vitacura, for the Bullet cluster, Abell 2204, Abell of the redshift of the scattering cluster. Santiago, Chile 2163, and a power spectrum analysis in In contrast, X-ray and optical surface 4 School of Physics and Astronomy, the XMM-LSS field. brightness dim with increasing redshift. Cardiff University, Wales, United The redshift independence makes the Kingdom SZE a uniquely sensitive method for dis- 5 Argelander Institute for Astronomy, Galaxy clusters covering and observing distant clusters. Bonn University, Germany 6 Center for Astrophysics and Space Galaxy clusters comprise dark matter Astronomy, Department of Astophysical and constituent galaxies with hot, low Instrument overview and Planetary Sciences, University of density ionised gas filling the space Colorado, Boulder, USA between the galaxies. This gas, known APEX–SZ observations were performed at 7 Max-Planck-Institut für extraterres as the intracluster medium (ICM), domi- 150 GHz (2 mm) from the 12-metre APEX trische Physik, Garching, Germany nates the baryonic mass in clusters. telescope (Güsten et al., 2006). Technical 8 National Institute of Standards and Thus, galaxy clusters are important labo- details of the receiver can be found in Technology, Boulder, USA ratories for studying various astrophysical Schwan et al. (2011). The telescope was

The Messenger 147 – March 2012 7 Telescopes and Instrumentation Schwan D. et al., APEX–SZ: The APEX Sunyaev–Zel’dovich Instrument

dent on the absorber are measured by the TES mounted at its centre. The TES is a thin superconducting film with a tran sition temperature higher than the reservoir temperature. A constant bias voltage is applied across the TES so that the total applied power (the electrical power dissipated in the TES plus optical power incident on the absorber) raises 1 mm the temperature of the sensor to pre- cisely the transition temperature. An increase (decrease) in the incident optical power produces a cancelling decrease (increase) in electrical power. Since the 25 mm voltage bias is held constant, the change in electrical power is measured as a change in current through the sensor. Figure 1. The TES bolometer array, with inset show- machined from a single aluminium block ing three spiderweb bolometers. Six identical trian- and mounted above the planar focal The bolometers are fabricated using gular sub-arrays are assembled into a single planar array, 133 mm in diameter, containing 330 bolome- surface. Each bolometer was centred standard photolithographic techniques. ters. Each bolometer has two leads which run from behind a cylindrical waveguide in the horn The absorber, the TES and the leads the spiderweb to bonding pads at the edge of its tri- array. There was a small gap between to bias the TES are deposited onto a 1 μm angle, visible as light traces between the bolometers. the horn array and the bolometers to pro- thick, low-stress silicon nitride (LSN) vide thermal isolation. Radiation not spiderweb membrane. The LSN spider- commissioned by the Max-Planck-Institut absorbed by a detector could leak radi- web is suspended by eight LSN legs für Radioastronomie, ESO and the ally to neighbouring detectors or be above a ~ 20 μm vacuum gap etched in Swedish Onsala Space Observatory for reflected back through the horns. This the silicon. The gap thermally isolates use with bolometric and heterodyne leakage resulted in a small, ~ 1%, optical the absorber from the silicon substrate. receivers. It is located near the ALMA site cross-talk between adjacent bolometers. The thermal conductance of the bo- at an altitude of 5107 metres on Llano lometer is set by a gold thermal link that de Chajnantor in the Atacama desert in The TES bolometers and frequency- runs from the TES to the thermal reser- Chile, which has exceptionally low water domain multiplexed (fMUX) readout sys- voir, parallel to the bias leads. The vapour conditions. In addition, the low tem used in the APEX–SZ focal plane APEX–SZ detector array is assembled latitude of the site (23 degrees south) have low noise, but require a cryogenic from six identical 55-element, triangular allows targeted observation of clusters system for their operation. The receiver subarrays (Figure 1). with rich multi-frequency datasets. Over- interior was cooled by a closed cycle lapping observations at different wave- pulse-tube cooler with cold stages at 60 K The APEX–SZ TES bolometers are read lengths enable a more complete study and 4 K. The mechanical cooler elimi- out with a SQUID (Superconducting and characterisation of clusters. nated the need for open reservoirs of liq- Quantum Interference Device) amplifier uid cryogens, greatly simplifying the fMUX, which allows several detectors to The telescope beam was coupled to the design and construction of the cryostat be read out by a single 4 K SQUID ampli- APEX receiver by a series of reimaging while reducing the cost and difficulty fier connected through a single pair of optics inside the Cassegrain cabin. The of remote observations. The bolometers wires (Lanting et al., 2004). Readout mul- full optical system had 58-arcsecond were further cooled to 280 mK by tiplexing enables the use of large detector FWHM (Full Width at Half Maximum) a three-stage helium sorption fridge. arrays by greatly reducing the thermal beams, diffraction-limited performance, load on the low temperature stage, the over a 22-arcminute field of view (FoV). complexity of cold wiring and the system This large FoV enabled APEX–SZ to map Detectors and readout cost. The APEX–SZ system uses seven the large angular size of low redshift detectors read out by one SQUID ampli- clusters, where the SZE signal can extend Each APEX–SZ bolometer consists of fier in each multiplexer module. beyond a 10-arcminute radius. an optical absorber coupled to a TES that is connected to a thermal reservoir by In the fMUX system, the bolometers are Within the receiver, the APEX–SZ focal a weak thermal link. The absorbing ele- biased with alternating voltages at carrier plane was 133 mm across and consisted ment is a 3 mm diameter gold spiderweb frequencies (0.3–1 MHz) that are much of 330 feedhorn-coupled TES (transition- (Figure 1). The spiderweb shape absorbs higher than the bolometer thermal band- edge sensor) bolometers. Of these, millimetre-wave radiation, provides a width, so the bias deposits a constant 280 detectors were read out. The detec- small cross-section to cosmic rays and power on the sensor. Each bolometer in tors and readout system are described in minimises the heat capacity of the the module is biased at a different fre- the next section. The horn array was absorber. Changes in optical power inci- quency. As described above, changes in

8 The Messenger 147 – March 2012 incident radiation modulate the current through the bolometer. This amplitude modulation translates the absorbed signal spectrum to sidebands centred around the carrier bias frequency. Since the currents from the different bolometers are separated in frequency, they can be combined and transmitted to the SQUID amplifier with a single wire. Furthermore, the bolometers are connected through Bullet A2163A2204 series inductor–capacitor circuits, each of which is tuned to the appropriate bias frequency, so all bias carriers can also be fed through a single line. As a result, each multiplexer module requires only a single pair of wires from the low temperature stage to the 4 K stage to read out all the A1835 A1689 RXCJ1347 RXCJ0232 RXCJ0532 bolometers in the module.

Imaging techniques

With bolometer receivers operating near the performance limit set by statistical RXCJ0245 A520 RXCJ1206 MS1054 RXCJ2214 photon noise, the main challenge in long- integration, millimetre-wave observations of spatially extended signals is the contamination from atmospheric noise. The emission from the turbulent atmosphere carrying water vapour typically A2537 RXCJ1023 A3404A1300 A2813 exhibits a Kolmogorov power spectrum (Tatarskii, 1961), with power increasing steeply with increasing angular scale. It also varies with time relative to the celestial signal. The APEX–SZ observation pattern and data reduction techniques RXCJ0528 RXCJ2243 A2744A209XLSSC006 exploit these characteristics to mitigate atmospheric noise.

APEX–SZ used a circular drift scan pattern to observe clusters. In the circular drift scan, the telescope performs circular scans which are stationary in azimuth RXCJ0516 RXCJ2337 A907 MACSJ1115MS0451 and elevation. After the source drifts across the array FoV, the telescope slews Figure 2. Signal-to-noise (S/N) maps of 28 clusters The procedure for removing atmospheric to the new source position. This circular in which the cluster signal map is divided by a noise noise also removes cluster signal, and estimate derived from jack-knife maps (a weighted drift scan pattern combines constant average of all scan maps in which a randomly the effect is especially pronounced low amplitude acceleration for efficiency selected half of the scan maps are multiplied by –1). for clusters of large angular size. We use with modulation of celestial signals The signal and noise maps are smoothed by con- a point source transfer function (PSTF) at timescales faster than typical atmos- volving with a 1-arcminute FWHM Gaussian function. to measure the effect of the instrument Each image is 15 arcminutes square. The Bullet pheric variations. map has a peak S/N roughly four times that of any beam and data filtering on the resulting other cluster and is shown with a different colour cluster map. Since the filtering process The data reduction algorithms remove table; all other clusters have the same S/N scale. is linear, the PSTF accurately encodes the the low frequency, large-scale atmos- distortion of the cluster signal. To gener- pheric noise using high-pass filters in the ate the PSTF, simulated point sources are time and spatial domains. A low-order spatial polynomial is fitted across the inserted into the real timestream and polynomial is fitted and subtracted from array for each time step. Figure 2 shows their spatial distortion is measured post- the data timestream for each channel. 28 cluster images measured with this processing. The transfer function encodes Additionally, a low-order two-dimensional procedure. information about the imaging quality. In

The Messenger 147 – March 2012 9 Telescopes and Instrumentation Schwan D. et al., APEX–SZ: The APEX Sunyaev–Zel’dovich Instrument

¦ࣳ Figure 3. APEX–SZ al. (2009). The cluster map of Abell 2163 maps of two clusters. is produced by applying a procedure Top: Map of the Bullet cluster (from Halverson similar to the CLEAN algorithm used in radio interferometry to deconvolve the ࣳ et al., 2009). The circle

in the lower left corner signal image and PSTF. The procedure, represents the 85-arc- detailed by Nord et al. (2009), allowed second FWHM map res-

) ࣳ olution, which is the the first direct reconstruction of the den- ! M result of the instrument sity and temperature profiles in a cluster HN

", beam, data reduction without a parametric model.

§* filter, and -1 arcminute ࣳ FWHM Gaussian

#DBKHM @S smoothing applied to the map. The contour Cluster gas constraints from the SZE and intervals are 100 μK . ࣳ CMB X-ray The + marker indicates the centroid position of the best-fit elliptical Joint SZE and X-ray observations allow -model. The * marker strong constraints to be placed on the G L R L R L R β indicates the position of cluster gas. The surface brightness of the 1HFGS RBDMRHNM) a bright, dust-obscured, SZE signal is proportional to the electron lensed galaxy, which density and the temperature of the intra- 29$CDBQDLDMSƅ* is detected at higher ",! frequencies (e.g., at cluster gas. X-ray emission from the gas l l l l 350 GHz by LABOCA; is dominated by thermal bremsstrahlung, Johansson et al., 2010), which is roughly proportional to the but does not signifi- l l l l l l cantly contaminate the square of the density and the X-ray cool- ,)XRQ measurement at 150 ing function, itself a weak function of l GHz. Bottom: Map of temperature. Multi-frequency data enable Abell 2163 (from Nord et detailed measurements of the cluster al., 2009). The APEX–SZ map, deconvolved from gas, including determination of the gas l the effects of the trans- temperature and mass, as well as their fer function, is overlaid distributions. with XMM-Newton X-ray l contours in units of 10–13 erg s–1 cm–2 arcmin–2. Halverson et al. (2009) fit the intracluster gas of the Bullet cluster to an elliptical & isothermal -profile (Cavaliere & Fusco- #$ l β

" Femiano, 1978) convolved with the PSTF.

#$ A Markov-chain Monte Carlo approach l is used to find the maximum likelihood in parameter space with an X-ray-derived prior on β. The analysis yields a core l radius rc = 142 +/– 18 arcseconds, an axial ratio 0.889 +/– 0.072, and a central l /$7l29AD@L temperature decrement –771 +/– 71 μKCMB (in units of temperature referred to a source at the CMB temperature), including 1 #$& a +/– 5.5 % flux calibration uncertainty. With a map of projected electron density particular, negative sidelobes indicate filtering on the sky signal. The Bullet clus- from Chandra data, the SZE-derived gas missing spatial information on larger ter is a system of two merging clusters (electron) temperature is Te = 10.8 +/– 0.9 angular scales. This is very similar to an (mass ratio ~ 1:10), which shows an offset keV. This temperature is lower than some interferometric synthesised beam, where between the gas and dark matter (Clowe previously reported X-ray temperatures, the inner portion of the Fourier plane, et al., 2006; also Figure 5). The map which could be biased towards hot, com- corresponding to very short baselines, is of Figure 3 is produced by masking a cir- pact regions. On the other hand, the often not sampled. In both cases, the cular region centred on the cluster source gas mass fraction derived from the SZE observation process is designed so that prior to fitting for the low-order polyno- map (under the approximation of hydro- the most relevant information is most mial filters, then applying the filters to the static equilibrium), is in good agreement densely sampled. entire dataset. The masking procedure with estimates from X-rays. limits attenuation of the cluster extended Figure 3 shows maps of the Bullet cluster emission at the expense of increased Nord et al. (2009) and Basu et al. (2010) and Abell 2163 made using two different map noise. The observations and data further explore cluster physics with SZE schemes to mitigate the effect of noise processing are detailed by Halverson et data combined with X-rays. Nord et al.

10 The Messenger 147 – March 2012 MFTK@QCHRS@MBD@QBLHMTSDR QDK@WDC BNNKBNQD

LDQFDQCHRSTQADC

Q L 5B D5 JD J Q * D 3

QQ QJOB

Figure 4. Derived radial profiles of cluster gas proper- non-parametric estimates for the total are the electron temperature and density, ties. Left: De-projected temperature for Abell 2163 mass and the gas mass, giving a gas respectively) for Abell 2204 and Abell with 1σ uncertainties (from Nord et al., 2009). The mass fraction profile, which again is con- 2163 shows that the entropy in the centre vertical arrow labelled “r200” marks the aproproximate virial radius (i.e., outer boundary) of the cluster. sistent with X-ray analyses. Nord et al. of a relaxed cluster is much lower than in Right: Entropy derived from APEX–SZ and X-ray data (2009) also combine the APEX–SZ SZE a violently disturbed merging cluster and for the relaxed cluster Abell 2204 (red circles) and the measurements of Abell 2163 at 150 GHz follows a power law (Figure 4). This result merging cluster Abell 2163 (blue squares). with 345 GHz measurements from the LABOCA camera on APEX and published (2009) derive gas density and tempera- measurements at other frequencies to Figure 5. Left: Multi-wavelength overlay (from ture profiles for Abell 2163 via the Abel place constraints on the peculiar velocity Halverson et al., 2009) on the Bullet cluster X-ray (XMM-Newton) colour image with SZE contours integral in Silk & White (1978). The derived of the cluster. Basu et al. (2010) present in white (100 μKCMB level intervals) and the weak- temperature profile shown in Figure 4, an analysis of the relaxed cluster Abell lensing surface mass density reconstruction con- representative of the bulk of the gas, is in 2204, where the assumption of spherical tours in green. Right: B, V, R colour image of the excellent agreement with the high gas- symmetry should be especially valid. central region of RXCJ0232.2-4420 (z = 0.28) with SZE contours in cyan (–90, –110, –130, –150, temperature estimates from X-ray data. A comparison of the derived entropy pro- –170 μKCMB) and smoothed weak-lensing conver- –2/3 The profiles have been converted to yield files (entropy isT e n , where Te and n gence contours in red (0.10, 0.11, 0.12, 0.13, 0.14).

–55°52ࣳ 1ࣳ = 253 kpc

54ࣳ ) 00 20

(J 56ࣳ

at ion

Declin 58ࣳ

00ࣳ

06h59m00s 58m30s 58m00s Right Ascension (J2000)

The Messenger 147 – March 2012 11 Telescopes and Instrumentation Schwan D. et al., APEX–SZ: The APEX Sunyaev–Zel’dovich Instrument

+ 1.4 2 –1 agrees with previous X-ray studies, but band powers) or 1.7– 1.3 Jy sr . Assuming A major aspect of the recent and future is derived independently without X-ray that the same sources are responsible work is a multi-wavelength analysis of spectroscopy. for the power fluctuations measured by clusters imaged with APEX–SZ (Figure 5). BLAST at 600 GHz, the spectral index For this reason, an optical follow-up + 0.4 of the source population is 2.6– 0.2. The programme has been conducted using Power spectrum analysis Atacama Large Millimeter/submillimeter the Wide Field Imager (WFI) at the 2.2- Array (ALMA) will resolve remaining ques- metre MPG/ESO telescope. Deep B-, V- Reichardt et al. (2009) use an SZE tions about contaminating sources by and R-band images obtained during image taken with APEX–SZ within the providing the missing statistical informa- 42 nights, together with archival data XMM-LSS field (0.8 square degrees, tion on population counts over all rele- from WFI and Subaru Suprime-Cam, pro- centred on the medium mass cluster vant wavelengths and by providing the vide excellent weak-lensing data for

XLSSUJ022145.2-034614, with 12 μKCMB ability to directly correct SZE images for 35 galaxy clusters at redshift 0.15–1 for root mean square noise at the centre) their point source contamination. the study of SZE and weak-lensing scal- for statistical analysis of the temperature ing relations. Our multi-frequency cluster fluctuations from undetected clusters data provide a unique sample to study and other sources. This type of fluctua- Future directions cluster mass scaling laws and baryon tion analysis applied to large datasets physics in unprecedented detail. places strong constraints on σ8, the nor- APEX–SZ was a pioneering instrument for malisation of the matter density power arcminute resolution SZE cluster observa- spectrum on the scale of roughly 10 Mpc. tions, advancing bolometer and readout References The power spectrum of the integrated technology and applying multi-wavelength Arnold, K. et al. 2010, SPIE, 77411E SZE from all clusters along the line of data analysis to constrain cluster gas Basu, K. et al. 2010, A&A, 519, A29 7 sight scales as σ8. The APEX–SZ image physics. The TES bolometer array with Bender, A. et al. 2012, in preparation was the most sensitive fluctuation meas- fMUX readout has been adopted for dedi- Carlstrom, J. E., Holder, G. & Reese, E. D. 2002, urement at 150 GHz at the time, with cated instruments with larger arrays, Ann Rev Astron. Astrophys., 40, 643 Cavaliere, A. & Fusco-Femiano, R. 1978, A&A, the resulting constraint on the matter notably the South Pole Telescope, with 70, 677 fluctuation amplitude beingσ 8 < 1.18 at 960 detectors, and POLARBEAR (Arnold Clowe, D. et al. 2006, ApJL, 648, L109 95 % confidence. Determination of the et al., 2010), a Berkeley CMB polarisation Güsten, R. et al. 2006, A&A, 454, L13 constraint requires consideration of con- experiment, with over 1200 detectors. Halverson, N. W. et al. 2009, ApJ, 701, 42 Johansson, D. et al. 2010, A&A, 514, A77 tamination of the SZE signal by other Lanting, T. M. et al. 2004, Nuclear Instruments and populations, such as radio sources or APEX–SZ took over 800 hours of scien- Methods in Physics Research A, 520, 548 dusty submillimetre (sub-mm) galaxies, tific data during its four years of opera- Nord, M. et al. 2009, A&A, 506, 623 which can be correlated with clusters as tions, targeting over 40 X-ray selected Reichardt, C. L. et al. 2009, ApJ, 694, 1200 Sarazin, C. L. 1988, X-ray emission from clusters of members or via gravitational lensing. clusters in a wide range of mass and red- galaxies (Cambridge: Cambridge University Press) The Reichardt et al. (2009) analysis esti- shift. Over 30 of these clusters were Schwan, D. et al. 2011, Review of Scientific mates the contribution of sub-mm galax- detected with high significance. The Instruments, 82, 091301 ies to the power spectrum at 150 GHz analysis of the full dataset is still ongoing Silk, J. & White, S. D. M. 1978, ApJL, 226, L103 Sunyaev, R. A. & Zel’dovich, Y. B. 1970, Comments + 0.9 –5 2 to be Cl = 1.1 – 0.8 × 10 μK (the ampli- (Bender et al., 2012). These observations on Astrophysics and Space Physics, 2, 66 tude of the angular power spectrum are being used to study the scaling of Tatarskii, V. I., ed. 1961, Wave Propagation in a for spherical harmonic multipole index l in the SZE signal with cluster mass (hydro- Turbulent Medium (New York: Dover) the range 3000–10 000 assuming flat dynamical and weak lensing).

Composite image of the complex galaxy cluster merger Abell 2744 (redshift 0.308) formed by com bining visible light images from NASA/ESA Hubble Space Telescope and VLT with an image of the hot intracluster gas (pink) from NASA Chandra X-ray Observatory data. A reconstruction of the dark matter in the cluster is overlaid (blue). See Science

NASA, ESA, Coe ESO, & D. CXC (STScI)/J. Merten (Heidelberg/Bologna) Release eso1120 for full details.

12 The Messenger 147 – March 2012 ESO/APEX/T. Preibisch et al. (Submillimetre); N. Smith, University of Minnesota/NOAO/AURA/NSF (Optical) eso1145. Release in found be can information Further Observatory. Interamerican Tololo Cerro the at image was made by the Schmidt Curtis telescope optical The K. 30 around at dust from emission to sensitive 870 μm of a wavelength at made were images LABOCA The observations. optical and (LABOCA) Camera BOlometer Apex Large APEX of secs, is highlighted (orange) in this combination kilopar 2.3 of adistance at situated (NGC 3372), Carina in Nebula Great the in dust cool The -

Astronomical Science Astronomical Science

Determining the Cepheid Period–Luminosity Relation Using Distances to Individual Cepheids from the Near- infrared Surface Brightness Method

Jesper Storm1 of these objects. One of the more elusive and the corresponding absolute variation Wolfgang Gieren 2 aspects of the PL relation is the effect of the radius from the radial velocities. By Pascal Fouqué 3 that metallicity has on the luminosity relating the observed angular diameter, Thomas G. Barnes4 of the Cepheids. It has long been argued the radius of the star and the distance to Thomas Granzer1 that there is an offset in the luminosity the star geometrically we can solve the Nicolas Nardetto 5 depending on metallicity, but in spite of equations for the distance and the mean Grzegorz Pietrzyński2,6 much effort there is still no unanimous stellar radius. In this sense the method Didier Queloz7 agreement even on the sign of the effect. is similar to the Baade–Wesselink method Igor Soszyński6 Storm et al. (2004) applied the near- for determining distances to pulsating Klaus G. Strassmeier1 infrared surface brightness method to stars. Michael Weber1 Milky Way Cepheids and found that the slope of the resulting PL relation dif- In Figure 1 we plot the angular diameters fered from that seen in Large Magellanic against the radius variation with the best 1 Leibniz-Institut für Astrophysik Cloud (LMC) PL relations, a finding that fit over-plotted for the LMC star HV877. Potsdam (AIP), Germany would have significant implications for the For all our fits we disregard the phase 2 Universidad de Concepción, Chile use of the relation as a distance indicator. interval between 0.8 and 1.0 where the 3 L’Institut de Recherche en Astrophy- Any improvement in our understanding star is contracting and the stellar atmos- sique et Planétologie (IRAP), Université of this relation is thus very important and pheres often exhibit signs of shocks de Toulouse, France has far-reaching consequences. (emission lines in the spectra) which can 4 University of Texas at Austin, McDonald affect the angular diameter measure- Observatory, USA ments. In the lower panel of Figure 1 the 5 Laboratoire Lagrange, UNS/CNRS/ The near-infrared surface brightness angular diameter is shown as a function OCA, Nice, France method of phase and it is clear that the match 6 Warsaw University Observatory, Poland between photometric angular diameter 7 Observatoire de Genève, Switzerland The near-infrared surface brightness (the dots) and the angular diameter method takes advantage of the fact that inferred from the radial velocity curve and a Cepheid star is radially pulsating. By the best fit distance (the blue curve) The near-infrared surface bright- observing the light curves in the visual agree rather well, except for the aforemen- ness method has been applied to and near-infrared (NIR), we determine the tioned phase region between 0.8 and 1.0. 111 Cepheids in the Milky Way, the variation of V-band luminosity and (V–K) Large Magellanic Cloud and the Small colour as a function of phase. These data The great advantage of the near-infrared Magellanic Cloud, and distances and can be used to determine the surface surface brightness method over, e.g., luminosities to the individual stars have brightness of the star and thus the angu- trigonometric parallaxes, is the fact that it thus been determined. As the Cepheid lar diameter as a function of phase. This can be applied to stars in other galaxies populations in these galaxies have relation is well established from interfero- as well as to nearby stars. The price to be significantly different metallicities, the metric observations of non-pulsating paid is that the method is very demand- effect of metallicity on the Cepheid stars (Fouqué & Gieren, 1997) and was ing in observing time as precise light Period–Luminosity (PL) relation can be later confirmed by Kervella et al. (2004) curves are necessary at both optical and directly determined. We show that by measurements of the angular diame- near-infrared wavelengths as well as pre- the K-band PL relation is very insensi- ters of Cepheids using the Very Large cise radial velocity curves. tive to abundance and argue that it Telescope Interferometer (VLTI). is the best Cepheid PL relation for distance determination. Observing the radial velocity curve for a A lot of data star allows us to determine the pulsational velocity curve for that star by Over the years a lot of data for Milky Way Motivation applying the so-called projection factor to Cepheids has been collected by many the observed radial velocities. The projec- workers in the field. This has allowed the The Cepheid Period–Luminosity relation tion factor accounts for the fact that the near-infrared surface brightness method provides a crucial step on the distance observed light from the radially pulsating to be applied to many Galactic stars. ladder in the quest to determine accurate star originates from the whole visible The first application to a small sample of distances out to cosmologically relevant hemisphere of the star and not just the extragalactic (Small Magellanic Cloud distances and thus constrain the value intercept between the stellar surface and [SMC]) Cepheids was successfully of the Hubble constant. It also allows the line connecting the observer and attempted by Storm et al. (2004). Gieren accurate distances to be measured to the stellar centre. From the pulsational et al. (2005) then applied the method nearby galaxies, providing the luminosities velocity curve we can compute the varia- to a number of Cepheids in the LMC. The of other scientifically interesting objects tion of the stellar radius as a function sample was still too small to delineate found in these galaxies and allowing of the phase. We thus have the angular a definitive PL relation for the LMC and so quantitative investigations of the physics diameter variation from the photometry we found it necessary to expand the

14 The Messenger 147 – March 2012 Figure 1. The upper sample significantly. At this time new pre- '5 panel shows the angular

B cise light curves in both the optical diameter versus the RD (Soszyński et al., 2008) and in the NIR

QB radius variation for the Cepheid HV877 with the (Persson et al., 2004) became available, Hl@ best fit over-plotted. The so radial velocity curves were called LHKK lower panel shows the for. We were granted time with HARPS Φ angular diameter as a function of phase. The on the 3.6-metre telescope at La Silla l l phase interval from 0.8 over three observing seasons. Over the ∆1L to 1.0 is always omitted first season we had 16 consecutive from the fit due to the photometric (!) half-nights in which the possible presence of shocks in the stellar shorter period stars were well covered; B in the next seasons the observations

RD atmosphere.

QB were carried out in service mode with l@ the diligent support of the La Silla staff.

LHKKH Φ In Figure 2 an example of a radial velocity curve is shown; again we have chosen /G@RD the LMC Cepheid HV877 which has a pulsation period of 45.2 days. The good phase coverage is very important and 320 Figure 2. The upper the observations in the last two observing panel shows the radial seasons were carefully planned to fill velocity curve for HV877 )

–1 300 the gaps remaining from the first cam-

s as observed with

m HARPS. In the lower paign. The lower panel in Figure 2 shows (k panel the epochs of the the timing of the observations, and it 280 RV individual observations becomes obvious that this kind of work are plotted. The different observing seasons have demands very careful scheduling to 260 00.5 1 been coded by different succeed and that the instrument is avail- Phase symbols and the coding able not just in a few long blocks of time, is the same in both pan- but also for single observing blocks dis- 320 els. tributed throughout the semester. Thanks

) to the flexibility of the La Silla support –1 300 s staff the programme could be completed m (k

in three seasons. For our 20 target stars 280 RV we obtained more than 450 data points with HARPS. 260 53600 5380054000 5420054400 54600 HJD–2500000 The effect of metallicity

Figure 3. The zero-point With the new data in hand, we have offset of the PL relations determined luminosities for a total of in the K-band (lower panel) and in the 36 LMC Cepheids with periods ranging Wesenheit index (upper from 3 to 80 days and can determine a 6

∆ panel). The three points PL relation in any of the observed photo- correspond to the SMC, metric bands (Storm et al., 2011b). For LMC, and Milky Way samples. the Cepheids in the Milky Way we have proceeded in exactly the same fashion (Storm et al., 2011a), supplementing the

available data with new radial velocity measurements from the echelle spectrograph on the STELLA robotic telescope * ,

∆ on Tenerife, Spain and analysing a total

of 70 fundamental mode Cepheids in a similar period range. It turns out that the 2," +,",HKJX6@X slopes of the two samples are very similar l l l l and we do not find significant evidence :%D'< that the slopes should be different. This

The Messenger 147 – March 2012 15 Astronomical Science Storm J. et al., Determining the Cepheid Period–Luminosity Relation

is a very important point to establish Figure 4. The universal when applying the PL relation as an K-band period–luminosity relation based on extragalactic yardstick, especially as our 111 Milky Way, LMC and l earlier work suggested that such an SMC Cepheids is effect was present. We then compare shown. directly the luminosities of the stars from these two samples as well as the five Cepheids in the SMC, which we have * re-analysed using the exact same proce- , l dure as for the other stars.

The resulting offset from the mean PL relation in the K-band and in the Wesen- heit index from our study is shown in l ,HKJX6@X"DOGDHCR Figure 3 (in the lower and upper panels +,""DOGDHCR respectively). The Wesenheit index is a 2,""DOGDHCR reddening-insensitive colour index based on the V- and I-band photometry, which KNF/ has been employed in particular by the Hubble Space Telescope Key Project on the extragalactic distance scale Gieren et al. (2005) applied the method effect of metallicity is very limited for (Freedman et al., 2001). We find a signifi- to LMC Cepheids and found the first metallicities between that of the SMC and cant effect in the sense that metal-poor evidence that the slopes are in fact the the Milky Way, we can then combine the stars are fainter than metal-rich stars by same in both the Milky Way and in the K-band luminosities for all 111 Cepheids 0.23 ± 0.1 mag per dex. The size of the LMC, but due to the availability of obser- from the Milky Way, the LMC and the effect is similar to the most recent one vations for only a few stars, the conclu- SMC. In Figure 4 we show the relation. adopted by the Key Project group. This is sion was not very firm. With the new data The dispersion is about 0.22 mag and is a very reassuring result as our method we confirm our findings from 2005, dominated by distance errors from our is entirely independent from the methods namely that the slopes are the same for analysis. However the resulting relation that they have employed. In the case of the two samples, but the projection is based on 111 stars so the slope and the K-band, the effect is significantly (a factor has a stronger period dependence zero point are statistically very well- factor of two) smaller and a null effect than originally anticipated, or at least defined. The LMC Cepheids provide an is consistent with the data. From the plot there is a period dependence of the LMC distance modulus of (m-M)o = 18.45 it is obvious that the constraint on the method which earlier had not been ac- ± 0.04 mag. metallicity effect could be made even counted for. Using the Benedict et al. stronger by expanding the sample of (2007) method, and taking trigonometric Persson et al. (2004) found the dispersion SMC stars and thus decreasing the size parallaxes for ten Cepheids to set the for their LMC PL relation in the K-band to of the error bar on this point. In fact this zero point and insisting that the distances be less than 0.1 mag, so the K-band PL would probably provide the strongest we derive for LMC Cepheids are inde- relation is an extremely powerful distance constraint that is currently achievable. pendent of pulsation period, we can well indicator, even for individual Cepheids. constrain the period effect and include it As the K-band is only weakly absorbed in the projection factor. Nardetto et al. by interstellar dust and, as shown here, The projection factor problem (2011) and references therein discuss the PL-relation is only weakly dependent from a theoretical point of view the possi- on metallicity, it has all the characteristics In our first application of the method to ble stellar atmosphere physics entering of an excellent distance indicator. Milky Way and SMC Cepheids, we could into the projection factor and they actu- only determine the slope of the PL rela- ally find a steeper relation than adopted in tion for the Milky Way sample, since the past, albeit not as steep as we find References the five SMC Cepheids all had about the from our purely empirical approach. This Benedict, G. F. et al. 2007, AJ, 133, 1810 same pulsation period. However, we difference implies that there is some Fouqué, P. & Gieren, W. 1997, A&A, 320, 799 found that the slope of the Milky Way physics somewhere which is still not well Freedman, W. L. et al. 2001, ApJ, 553, 47 PL relations differed significantly from the understood. Gieren, W. et al. 2005, ApJ, 627, 224 slopes of the PL relations obtained for Kervella, P. et al. 2004, A&A, 428, 587 Nardetto, N. et al. 2011, A&A, 534, L16 LMC Cepheids, based on their apparent Persson, S. E. et al. 2004, AJ, 128, 2239 luminosity and assuming the same dis- The universal PL relation Soszyński, I. et al. 2008, Acta Astr., 58, 163 tance to all the LMC Cepheids. If this Storm, J. et al. 2004, A&A, 415, 531 were to hold true, the PL relation would With the modified projection factor Storm, J. et al. 2011a, A&A, 534, A94 Storm, J. et al. 2011b, A&A, 534, A95 be a very poor extragalactic yardstick. from above and the knowledge that the

16 The Messenger 147 – March 2012 Astronomical Science

Resolved Stellar Populations with MAD: Preparing for the Era of Extremely Large Telescopes

Giuliana Fiorentino1 A classical observational approach optical bands. From theoretical evolu Eline Tolstoy 2 uses accurate multi-colour photometry tionary tracks we know that in an optical– Emiliano Diolaiti 1 of resolved stellar populations to create IR CMD the features will be stretched out Elena Valenti 3 detailed colour–magnitude diagrams due to the long colour baseline. There Michele Cignoni1 (CMDs), which can be interpreted using exist robust techniques to make detailed A. Dougal Mackey 4 sophisticated statistical techniques. How- analyses of observed CMDs by compar- ever this approach requires wide-field ing them to theoretical models (e.g., images with high, stable spatial resolu- Cignoni & Tosi, 2010). Whilst in the optical 1 INAF–Osservatorio Astronomico di tion. In this respect the Hubble Space domain the theoretical stellar evolution Bologna, Italy Telescope (HST) has revolutionised the models are well calibrated, in the NIR they 2 Kapteyn Astronomical Institute, Uni photometric study of resolved stellar pop- still have to be fully verified for a range versity of Groningen, the Netherlands ulations. However it remains a relatively of stellar evolutionary phases. Moreover 3 ESO small telescope, with a diffraction limit at this aspect needs to be confirmed from 4 Research School of Astronomy & Astro- optical wavelengths that is approached an observational point of view using the physics, Mount Stromlo Observatory, by the image quality of adaptive optics actual photometric accuracies. Australia (AO) imagers working in the infrared on 8-metre-class ground-based telescopes. AO currently only works effectively at NIR An AO imager on an Extremely Large wavelengths and this is likely to remain

Deep images in J, H and Ks filters using Telescope (ELT) will of course lead to dra- the case for the foreseeable future. This the Multi-conjugate Adaptive optics matic improvements in spatial resolution implies adapting current CMD analysis Demonstrator (MAD) on the VLT have in the infrared. techniques, which are almost exclusively been made of a region of the Large carried out at optical wavelengths. These Magellanic Cloud near the globular clus- At the moment most ground-based AO changes bring several challenges to ter NGC 1928. Our aim was to assess imagers are single guide star systems, interpreting the images and the first step if accurate photometry could be carried which have very small fields of view with is to obtain useful training datasets. out down to faint limits over the whole a strong variation in the point spread MAD field of view. In addition we tested function (PSF) over this field. In order to how accurate a basic analysis of the be able to expand the field size and uni- Our MAD experiment properties of the stellar population formity of the PSF, a technique called could be made using the near-infrared multi-conjugate adaptive optics (MCAO) The Multi-conjugate Adaptive optics MAD photometry, compared to the is required. Here we describe an experi- Demonstrator on the VLT has been em Hubble Space Telescope optical pho- ment with the prototype MCAO imager, ployed to obtain deep images in J, H and

tometry. This study has implications for MAD, at ESO’s Very Large Telescope Ks filters in a region of the Large Magel- understanding the issues involved in (VLT; see Marchetti et al. [2007] for de- lanic Cloud near the globular cluster Extremely Large Telescope imaging of tails). It is anticipated that ELT imaging NGC 1928. This field has previously been resolved stellar populations. will be carried out with MCAO-fed imag- imaged at optical wavelengths by the ers. ELTs are likely to be infrared (IR) opti- Advanced Camera for Surveys (ACS) on mised, using AO-based instrumentation HST. MAD, was mounted as visitor instru- Archaeological evidence about the prop- (Gilmozzi & Spyromilio, 2007). This means ment on Unit Telescope 3 (UT3) at the erties of individual stars over a large range that sensitive high-resolution ground- VLT for three observing runs in 2007 and of ages can tell us much about galaxy based imaging will only be possible at 2008. MAD is a demonstrator instru- formation and evolution processes from wavelengths starting from (perhaps) opti- ment built to prove the MCAO concept the present day back to the early Uni- cal I-band, with a peak efficiency in the on the sky and is able to measure the verse. Low-mass stars have very long near-IR (NIR). Both sensitivity and spatial atmospheric turbulence using three natu- and passive lives and their photospheres resolution are important for the study of ral guide stars located, ideally, at the hold time capsules of the gas from the resolved stellar populations, especially vertices of an equilateral triangle within a interstellar medium out of which they for compact galaxies and also for more field of view of 2 arcminutes in diameter. formed. Thus populations of individual distant galaxies beyond the Local Group. This approach allows the turbulence to stars of a range of ages provide uniquely Hence it is valuable to carry out pilot be corrected over the whole field of view detailed information about the changing studies in this wavelength range with the (see Marchetti et al., 2006; 2007). The properties of galaxies: how the rate of AO instruments available today. 2048 by 2048 pixel NIR detector available star formation and chemical composition in MAD covered only a 1-arcminute varied from its formation to the present NIR photometry does have several ad square region of the full field of view, with day. Such studies can provide a link vantages: it can limit the effects of high 0.028-arcsecond square pixels. We between the local Universe, high redshift and/or spatially variable extinction towards used all three broadband filters available:

surveys and theoretical simulations of or inside a stellar field and it can also pro- J, H and Ks with total exposure times of galaxy formation and evolution. vide enhanced temperature sensitivity in 60 minutes in Ks, and 42 minutes in the J a CMD, in particular when combined with and H filters.

The Messenger 147 – March 2012 17 Astronomical Science Fiorentino G. et al., Resolved Stellar Populations with MAD

Figure 1. MAD field of LMC ﬁeld close to NGC 1928 (K -band) H-band). The maximum Strehl ratios s view (yellow and white) obtained in both fields reach, or even GS1(R) = 10.2 mag on top of an ACS/HST image (from Mackey et slightly exceed, the performance GS2(R) = 10.4 mag GS3 al., 2004). The natural expected for MAD in “star-oriented” refer- GS3(R) = 11.1 mag guide stars (green cir- ence wavefront mode. As an example, cles) are within a circle the maximum Strehl ratio in K -band was of diameter 2 arc- s minutes. The asterism is predicted to be between 11% and 24% centred at RA = 05:21:11 for seeing decreasing from 1.0 to 0.7 arc- GS1 and DEC = –69:27:32. seconds. The two pointings F1 F1 and F2 are shown. From MAD has been able to reach a FWHM of GS2 Fiorentino et al. (2011). twice the diffraction limit in H- and Ks- F2 bands at the large zenith distances typical of the LMC. The maximum Strehl N ratio we have obtained in Ks-band is larger E than 30 %, which is better than the ex pected performance (24%) for MAD in “star-oriented” mode in our seeing condi- The MAD requirement of three bright served fields, using an IDL program pro- tions (seeing larger than 0.7 arcseconds). natural guide stars within a circle of two vided by E. Marchetti. Despite the strong The uniformity and the stability of the arcminutes in diameter combined with variation over the field, the best FWHM correction varied not only with the posi- our desire to image a region for which was achieved in field F2 (0.08 arcsec- tion from the guide star asterism, but also HST optical photometry was already onds) and it is close to the H filter diffrac- with airmass and seeing conditions. The available, limited the possible sky cover- tion limit (0.05 arcseconds). In contrast, complex dependency of these factors age. We found a suitable asterism in the uniform PSF in field F1 only reaches a prevented us from making a direct com- a region close to the Large Magellanic FWHM of 0.14 arcseconds, which is parison between our results and other

Cloud (LMC) globular cluster NGC 1928 twice the Ks diffraction limit (0.07 arcsec- MAD studies. However, in other experi- (Figure 1). The area mapped by MAD onds). The mean FWHM is 0.12 arcsec- ments MAD was successfully able to observations is completely covered by onds for H-band and 0.20 arcseconds for reach the diffraction limit in Ks-band (e.g., ACS images (Mackey et al., 2004). the Ks-band. The Strehl ratio shows a Falomo et al., 2009). similar spatial behaviour to the FWHM. For our MAD images we estimated the The Strehl ratio in field F1 is quite uniform stability of both the full width at half with values ranging from 5 to 15 % (in Figure 2. The FWHM variation (in arcseconds) measured across the field F1 (see Figure 1) in theK s-band maximum (FWHM, see Figure 2) and the Ks-band), whereas this distribution varies filter (left) and across the field F2 in theH -band filter Strehl ratio of the PSF across the ob rapidly in field F2 from 5 to 25 % (in (right). From Fiorentino et al. (2011).

0.07 0.07 FWHM Map FWHM Map

60 60 0.0 0. 0. 21 0.11 0. 0.11

18 12

0. 15 9

50 0.15 50 0.0 0.15

40 0.19 40 0.19

0.24 0.24 csec csec 30 9 30 ar ar 0.0 21 15 0. 0. 0 0. 12 0.28 .1 15 0.12 0.28 20 8 0. 20 0. 24 18 0. 0.32 0.32 10 0.15 10 0. 0. 21 21 0. 24 0.36 0.36 0 10 20 30 40 50 60 0 10 20 30 40 50 60 arcsec arcsec 0.40 0.40

18 The Messenger 147 – March 2012 –0.05 Residual FWHM Map

0. –0.04

0. 00

02 01

1&! 1&! 50 –0.03

0.01 0.00 40 –0.01

F ,2 1" ,2 1"

0.00 5 L@ csec 30 0. ar

0.00 0. 0.01 20 00

0.01 0.03 10 0. 00 0.04 0 0 10 20 30 40 50 60 arcsec 0.05 5m(L@F 5m*RL@F

Figure 3. Residual map of the observed PSF vs. the Figure 4. Colour–magnitude diagrams obtained com- model (in arcseconds) created with DAOPHOT bining purely optical V, I (from HST/ACS) and optical for the challenging case of field F2 inH -band. From and near-infrared V, Ks (from HST/ACS and MAD) Fiorentino et al. (2011). filters are shown at left and right (from Fiorentino et al., 2011). Red boxes are used to highlight the evolutionary phases considered in the CMD analysis, i.e. The AO performance was so good that The colour–magnitude diagrams the Main Sequence (MS), the Red Clump (RC) and the Red Giant Branch (RGB). we were able to perform photometry using standard photometric packages, The combination of optical and IR as DAOPHOT/ALLSTAR (Stetson, 1987; photometry is shown in Figure 4, (see and gravity of each star by interpolation 1994). The approach is to model the Fiorentino et al. [2011] for all the filter in the metallicity and age grid of a library PSF as the sum of a symmetric analytic combinations). The longest colour base- of stellar evolution tracks. bivariate function (typically a Lorentzian) line to Ks-band stretches out the main and an empirical look-up table represent- CMD features (right panel) the most, Using our final optical/IR catalogue ing corrections to this analytic function hence allowing an easier and more pre- (VIJHKs), where the optical observations computed from the observed brightness cise separation of different stellar popu come from ACS/HST, we could deter- values within the average profile of sev- lations in all evolutionary phases. In mine how well stellar evolution models in eral bright stars in the image. This hybrid Fiorentino et al. (2011), we performed a the different filter combinations match PSF seems to offer adequate flexibility basic application of the well-established our data for the most likely SFH, derived in modelling the complex PSFs that we CMD synthesis methods to interpret by Holtzman et al. (1999) for a nearby found. Furthermore, the empirical look-up our optical/IR CMDs in terms of a likely field in the LMC. Given the uncertainties table makes it possible to account for star formation history (SFH). The HST/ACS in the IR stellar evolution tracks, we pay the PSF variations (linear or quadratic) photometry is very deep (at least 4 mag special attention to comparing optical vs. across the chip. We have compared the below the Main Sequence Turn Off infrared or purely infrared CMDs. We observed PSFs, and their variation over (MSTO), i.e. V, I ~ 26 mag) and the com- conclude that it is possible to apply the the field, with the PSF models created pleteness is 100 % at the level of our same techniques for determining SFHs in using DAOPHOT; an example is shown in faintest NIR observations. The set of syn- V- and I-bands to IR datasets, even if Figure 3. Our experience in dealing with thetic populations (each with ~ 50 000 optical filters are clearly more accurate in quite a large dataset of real MAD images stars) that have been compared with our this case. The optical/IR and purely IR (see Fiorentino et al. [2011] for details) final catalogue have been simulated using analyses show the same trends, sug suggests that a uniform correction is pre- the package IAC-STAR (Aparicio & Gallart, gesting that the IR analysis could be im ferred to a very high, but non-uniform, 2004), which generates synthetic CMDs proved, when deeper more accurate Strehl ratio. for a given SFH and metallicity function. photometry will be available. Another key Composite stellar populations are calcu- role for the IR analysis will be played lated on a star-by-star basis, by comput- by the theoretical calibration of IR stellar ing the luminosity, effective temperature evolution tracks.

The Messenger 147 – March 2012 19 Astronomical Science Fiorentino G. et al., Resolved Stellar Populations with MAD

As by product of our analysis we could and deep wide-field stellar photometry References estimate the distance to the LMC by required to make detailed colour– Bono, G. et al. 2009, in Science with the VLT in the means of the infrared red clump method magnitude diagrams is possible with ELT Era, ed. A. Moorwood, p. 67 and we obtained 18.50 ± 0.06 (random MAD. Although MAD was a demon- Campbell, M. A. et al. 2010, MNRAS, 405, 421 error) ± 0.09 (systematic error), which strator instrument with a small engineer- Cignoni, M. & Tosi, M. 2010, Advances in is in very good agreement with dis- ing grade detector, the experiment Astronomy, 2010 Deep, A. et al. 2011, A&A, 531, A151 tances measured with other independent worked very well. A future ELT will sample Falomo, R. et al. 2009, A&A, 501, 907 methods. the atmospheric turbulence more accu- Ferraro, F. R. et al. 2009, Nature, 462, 483 rately, which means that the peak correc- Fiorentino, G. et al. 2011, A&A, 535A, 63 tion achievable with MAD is smaller than Gilmozzi, R. & Spyromilio, J. 2007, The Messenger, 127, 11 Future prospects that expected from an ELT. This means Holtzman, J. A. et al. 1999, AJ, 118, 2262 that future ELT MCAO instrumentation will Mackey, A. D. & Gilmore, G. F. 2004, MNRAS, We, among others (Bono et al., 2009; be much more stable in terms of uni 352, 153 Ferraro et al., 2009; Campbell et al., formity and performance (e.g., Deep et Marchetti, E. et al. 2006, SPIE, 6272, 21 Marchetti, E. et al. 2007, The Messenger, 129, 8 2010; Sana et al., 2010; and Fiorentino al., 2011). Sana, H. et al. 2010, A&A, 515, A26 et al., 2011), have shown that the accurate Stetson, P. B. 1987, PASP, 99, 191 Stetson, P. B. 1994, PASP, 106, 250

Colour image of the young open star cluster NGC 2100 situated in Large Magellanic Cloud taken with the EMMI instrument on the ESO New Technology Telescope (NTT) at the La Silla Observa- tory. Exposures in broad B-, V- and R-bands were combined with narrowband images centred on the emission lines of Hα, [N ii] 6583 Å and [S ii] 6716,6731 Å. Data for this image were selected by David Roma as part of the ESO Hidden Treasures competition. More details can be found in Release eso1133.

20 The Messenger 147 – March 2012 Astronomical Science

The Search for Intermediate-mass Black Holes in Globular Clusters

Nora Lützgendorf1 lution on all scales. Supermassive black cess to explain the rapid growth of Markus Kissler-Patig1 holes (SMBHs) have masses from a mil- SMBHs is through the merger of smaller Tim de Zeeuw1, 2 lion up to several billions of solar masses seed black holes of intermediate mass Holger Baumgardt 3 and are situated in the centres of massive (between 100 and 10 000 solar masses, Anja Feldmeier1 galaxies. When a SMBH accretes the e.g., Ebisuzaki et al., 2001). Karl Gebhardt 4 surrounding material it emits tremendous Behrang Jalali5 amounts of energy. This energy can be Numerical simulations have shown that Nadine Neumayer1 observed at all wavelengths and is detect- intermediate-mass black holes can form Eva Noyola 6 able at large distances. The most active in runaway mergers of stars in a dense galaxies are quasars and have been a environment, such as young star clusters. puzzle to astronomers since their discov- Also, ultraluminous X-ray sources at off- 1 ESO ery in the early 1960s. Their presence at centre positions in galaxies provide strong 2 Sterrewacht Leiden, Leiden University, large redshifts indicates that they existed evidence of massive black holes in stel- the Netherlands at a time when the Universe was only one lar clusters (e.g., Soria et al., 2011). The 3 School of Mathematics and Physics, billion years old or less, at a very early globular clusters observed today are as University of Queensland, Brisbane, stage of structure formation (Fan, 2006) old as their host galaxy: could they have Australia when the first galaxies were just forming. delivered seed black holes, the missing 4 Astronomy Department, University of How could a black hole with a mass of a link, in the crucial early stage of galaxy Texas at Austin, USA billion or more solar masses have formed formation? 5 I. Physikalisches Institut, Universität zu so early in the history of the Universe, Köln, Germany when galaxies were not yet fully evolved? A further motivation for studying IMBHs 6 Instituto de Astronomia, Universidad is that observations have shown a cor Nacional Autonoma de Mexico (UNAM), Black holes can grow in two ways: relation between the masses of SMBHs Mexico through the accretion of surrounding and the velocity dispersion of their host material and by merging with other black galaxies (see Figure 1 and e.g., Ferrarese holes. Even if a black hole accretes at & Merritt, 2000; and Gebhardt et al., Intermediate-mass black holes (IMBHs) the highest possible rate (the Eddington 2000). Extrapolating this relation to the fill the gap between supermassive rate) for a billion years, it would not reach mass ranges of IMBHs yields a velocity and stellar-mass black holes and they one million solar masses if it started with dispersion of between 10 and 20 km/s, could act as seeds for the rapid growth a one solar mass seed. Observations such as those observed from the stars of supermassive black holes in early have also shown that SHMBs do not con- in globular clusters. The origin and inter- galaxy formation. Runaway collisions of stantly accrete at the efficiency of the pretation of this relation is still under massive stars in young and dense stel- Eddington rate. Thus, the preferred pro- debate and it is not known whether it lar clusters could have formed IMBHs that are still present in the centres of 10 globular clusters. We have resolved the 10 central dynamics of a number of glob ular clusters in our Galaxy using the FLAMES integral-field spectrograph at the VLT. Combining these data with photometry from HST and comparing 10 8 them to analytic models, we can detect the rise in the velocity dispersion profile that indicates a central black hole.

Our homogeneous sample of globu- ) ी lar cluster integral-field spectroscopy (M 10 6 allows a direct comparison between BH clusters with and without an IMBH. M Ω Cen

The missing link? NGC 6388 Figure 1. The MBH– σ 4 relation for supermas- 10 G1 Black holes have fascinated humanity for M 15 sive black holes in galaxies is shown. Globular almost three centuries. Objects of pure 47 Tuc Globular Clusters clusters and dwarf gal- gravity forming singularities in spacetime axies lie at the extrapo- were first postulated by John Michell lation of the relation in 1783 and still seem enigmatic to physi- towards lower black 102 hole masses. The points cists today, fuelling a strong drive to 10 100 for a few globular clus- understand their nature, growth and evo- σ (km/s) ters are plotted.

The Messenger 147 – March 2012 21 Astronomical Science Lützgendorf N. et al., The Search for Intermediate-mass Black Holes

UT2INTEGRATION IN OZPOZ ARGUS ARRANGEMENT Figure 2. A schematic of the VLT FLAMES ARGUS integral field unit 300 μm in the Ozpoz fibre posi- Sky

Spectr tioner is shown (centre).

button 15 The ARGUS fibre geom-

Tumbler subslits etry and the allocation Argus ograph

2 mm of fibres into sub-slits head 4. feeding the GIRAFFE spectrometer is shown at right. 6.6 mm Array of 22 × 14 channels truly holds at the lower mass end. The hole. Obtaining velocities and velocity and Planetary Camera 2 (WFPC2) in the study of IMBHs and their environments dispersions in the centres of globular clus- I-band (F814W) filter in May 1998 (GO- might shed light on many astrophysical ters, however, is very difficult due to 6804, PI: F. Fusi Pecci) and retrieved from problems, helping us to develop a better the high stellar densities in these regions. the European HST archive. The choice understanding of black hole formation Resolving individual stars in the centre of filter is related to our spectral observa- and galaxy evolution. and measuring spectra with ground- tions, which are obtained in the wave- based telescopes requires adaptive op length range of the calcium triplet, a prom- The idea that IMBHs might exist in globu- tics, extraordinary weather conditions inent absorption feature around 860 nm lar clusters was first proposed decades and time-consuming observations. For and ideally suited to the measurement ago. Many observational attempts to find these reasons we used a different method of radial velocities. By measuring the rela- direct evidence of a black hole in globu- — integrated light measurements (Noyola, tive shift of the calcium triplet through lar clusters have followed. However, most 2010; Lützgendorf, 2011). absorption line fitting, we obtained a ve studies have only observed the light locity for each spectrum. The final veloc- profiles in the centre of the clusters and We used the large integral field unit ity map for NGC 2808 is also shown in compared these with models. A central ARGUS, a mode of the FLAMES facility Figure 3. Velocity maps are instructive black hole does produce a prominent mounted on Unit Telescope 2 of the Very to look at and good for identifying sus cusp in the surface brightness profile of Large Telescope (VLT). Figure 2 shows picious features, but in order to compare a globular cluster (Bahcall & Wolf, 1976; schematically the properties of the instru- our data to model predictions we need Baumgardt et al., 2005), but this signature ment. ARGUS consists of a 22 × 14 array the velocity dispersion profile. It is can be confused with the one expected of microlenses (called spaxels for spatial the velocity dispersion s, or the second from a core-collapse process. For this pixels) with a sampling of 0.52 arcsec- moment of the velocity (the quadratic reason, it is crucial to study the kinematic onds per microlens and a total aperture sum of the expectation value of the veloc- profile in addition to the light profile. of 11.5 by 7.3 arcseconds on the sky; ity and the velocity dispersion), which this field allows the core of a globular holds information about the mass distri- Our group set out to search for the kine- cluster to be covered in a few pointings. bution. matic signatures of intermediate-mass A more detailed description of FLAMES black holes in Galactic globular clusters and the ARGUS mode can be found in In order to derive a velocity dispersion by trying to understand which of our Pasquini (2002) and Kaufer (2003). For profile, we used radial bins around the observed globular clusters host an inter- the observations the GIRAFFE spectro- centre of the cluster and combined all mediate-mass black hole at their centre graph was set to the low spectral resolu- the spectra included in each bin. The and which do not. With a sample of tion mode LR8 (coverage 820–940 nm absorption lines of the resulting spectra ten clusters, our goal is to understand at a spectral resolution of 10 400) and the are broadened due to the different veloci- whether the presence of an IMBH corre- ARGUS unit was pointed to different ties of the individual stars contributing lates with any of the cluster properties. positions, each of them containing three to the spaxels. Measuring the width of exposures of 600 s with 0.5 arcsecond these lines yields the velocity dispersion dithering, to cover the entire core radius. for each bin, thus a velocity dispersion Mapping the integrated light The position angle of the long axis of profile as a function of radius. Great care the integral field unit was varied from 0 to is taken to measure the true velocity A central black hole in a dense stellar 135 degrees in order to achieve maximum dispersion and not artefacts of the instru- system, such as a globular cluster, coverage of the cluster centre. ment, the data reduction or the data affects the velocities of its surrounding combination process. stars. As an additional gravitational Figure 3 shows the combined pointings potential it causes the stars in its vicinity from the ARGUS observations of the to move faster than expected from the cluster NGC 2808 together with the re Black hole hunting gravitational potential of the cluster itself. constructed field of view on the Hubble Measuring this difference provides an Space Telescope (HST) image. The HST A black hole is suspected when we see estimate of the mass of the possible black images were obtained with the Wide Field a difference between the measured ve-

22 The Messenger 147 – March 2012 object spectrographs such as FLAMES/ Medusa. A Fabry Perot instrument can

W also operate as an integral field unit: nar-

%KT row wavelength band, wide-field images at a series of different wavelength steps are recorded. This results in a set of λ ML images with high spatial resolution from

'23(, &$ 1&421$".-2314"3$# 5$+."(38, / which the stellar absorption line features can be extracted by combining the photometry of the objects from each wavelength bin (Gebhardt et al., 1992).

After deriving the full kinematic and photometric profiles, the information is fed into models. We use different kinds of models. The first and the simplest kind are analytical Jeans models. The models take the surface brightness profile, de ll ll l l JLR project it into a three-dimensional density profile and predict a velocity dispersion Figure 3. The process of deriving a velocity disper- since the density of stars is lower than in profile. The latter is then compared to the sion profile with integral-field spectroscopy is illus- the centre. The instruments we used actual measured velocity dispersion pro- trated. Shown are the field of view on the HST image (left panel), the ARGUS reconstructed pointing to obtain the outer kinematics are the file. We study the variations of the model (middle panel), a datacube with each spaxel (spatial Rutgers Fabry Perot on the Blanco when including the additional gravita- element) being a spectrum in the calcium triplet 4-metre telescope at Cerro Tololo Inter- tional potential of a black hole into the region (shown above), and the resulting velocity map American Observatory (CTIO) and multi- equations. By trying different black hole (right panel). The circles indicate the bins applied to derive the velocity dispersion profile. locities and the expected velocities from the gravitational potential of the cluster derived from its light distribution only. In order to determine these expected veloc ities, we needed an estimate of the stellar density in the cluster. This is done by taking images from HST and measuring the surface brightness profile. We determined the photometric centre of the cluster by measuring the symmetry point of the NGC 1851 NGC 1904 NGC 2808 spatial distribution of the stars. Using colour–magnitude diagrams, we also identified the stars which do not belong to the cluster.

In addition to the VLT and HST observations, data from other instruments are required for kinematic measurements of outer regions that are too faint to be studied using integrated light. In order to NGC 5286 NGC 5694 NGC 5824 detect a black hole, only the innermost points are critical, but in order to understand the global dynamics of the cluster and to determine its mass, the entire velocity dispersion profile is needed. The outer kinematics can be obtained through the measurement of individual stars,

Figure 4. Velocity maps of all the Galactic globular clusters of our sample (except Omega Centauri) are shown superposed on HST images. NGC 6093 NGC 6266 NGC 6388

The Messenger 147 – March 2012 23 Astronomical Science Lützgendorf N. et al., The Search for Intermediate-mass Black Holes

NGC 6388 NGC 2808 30 10 16 8 3 15 MBH = 45 × 10 Mी 6 2 χ 2 10 χ 4 14 5 25 2 0 0 0 10 20 30 40 0 1000 2000 3000 4000

MBH (Mी) MBH (Mी) 12 s) s)

MBH = 0 km/ km/ ( 20 ( S S 10 RM RM V V

8 15

6 10 0.0 0.51.0 1.5 0.0 0.51.0 1.52.0 2.5 log r (arcsec) log r (arcsec)

Figure 5. The velocity dispersion profiles of the ities. Then, the system evolves by letting is rather flat and an IMBH larger than globular clusters NGC 6388 and NGC 2808 are the particles interact gravitationally. By ~ 1000 M is excluded. Among all our shown. Overplotted are a set of Jeans models with ⊙ different black hole masses (grey lines) and the following the evolution of this cluster over candidates we find clusters like NGC 2808 best-fit model (black line). In the corner of each plot a lifetime (~ 12 Gyr), we studied its evolu- as well as clusters where the central the variation of χ2 of the fit as a function of black- tion in detail and compared the final state points of the velocity dispersion profile are hole mass is shown. The shaded area marks the with the observations. By changing the rising just as in NGC 6388 and Omega region for Δχ2 < 1, and thus the 1σ error on the black hole mass. While for NGC 2808 the profile is rather initial conditions, we found the simula- Centauri. flat and does not require a black hole, NGC 6388 tions which fitted the observed data best has a steeper profile and a best-fit model with and learnt about the intrinsic properties After finalising the analysis and the mod- a ~ 17 000 M black hole (Lützgendorf et al., 2011, ⊙ of the globular clusters and their black elling of all the clusters in our sample, Lützgendorf et al., 2012, in prep.). holes, such as mass-to-light ratio varia- we will be able to start correlating the tions and the anisotropy in the cluster. presence and mass of an IMBH with the masses, we find which model fits our cluster properties. We will also be able data best. Figure 5 shows the entire to set the selection criteria for further velocity dispersion profile for two exam- Black hole or no black hole? studies and use our experience and ples: NGC 2808 and NGC 6388 with expertise to extend the search for IMBHs a set of Jeans models overplotted. A Our sample, so far, includes ten Galactic to more distant objects and larger sam- central black hole causes a rise in the globular clusters observed in 2010 and ples. This strategy will advance our velocity dispersion profile. In the case of 2011, including the pilot project target knowledge of globular cluster formation NGC 2808 no black hole is needed in Omega Centauri. All of them have been and evolution and bring us closer to an order to explain the observed data but in analysed and velocity maps have been understanding of black hole growth and the case of NGC 6388 the profile shows computed (see Figure 4 for all the clus- galaxy formation. a clear rise, making this cluster an ex ters except Omega Centauri). Modelling cellent candidate for hosting an interme- all the clusters, however, is not straight- diate-mass black hole. forward as each cluster shows peculi References arities: some show very shallow kinematic Bahcall, J. N. & Wolf, R. A. 1976, ApJ, 209, 214 In addition to these analytical models, profiles, while others seem to have multi- Baumgardt, H., Makino, J. & Hut, P. 2005, N-body simulations are employed in order ple centres — one photometric and one ApJ, 620, 238 to reproduce the observations (Jalali kinematic. Ebisuzaki, T. et al. 2001, ApJ, 562, L19 et al., 2011). This approach is crucial in Fan, X. 2006, New A Rev., 50, 665 Ferrarese, L. & Merritt, D. 2000, ApJ, 539, L9 order to exclude alternative scenarios However, for most of the clusters we are Gebhardt, K. et al. 2000, AJ, 119, 1268 which could cause a kinematic signature confident that we can determine from Gebhardt, K. et al. 1992, in Bull. AAS, 24, 1188 similar to a black hole, such as a cluster the central kinematics whether they are Jalali, B. et al. 2011, MNRAS, 400, 1665 of dark remnants (e.g., neutron stars). likely to host an intermediate-mass black Kaufer, A. et al. 2003, The Messenger, 113, 15 Lützgendorf, N. et al. 2011, A&A, 533, A36 N-body simulations are ideally suited for hole or not and that good constraints on Noyola, E. et al. 2010, ApJ, 719, L60 globular clusters since their kinematics their masses can be provided. The two Pasquini, L. et al. 2002, The Messenger, 110, 1 are only determined by the motions of examples in Figure 5 show that in the Soria, R. et al. 2011, MNRAS, in press, arXiv: IIII.6783 their stars/particles. Assuming certain ini- case of NGC 6388 a model with a black tial conditions, the stars are distributed hole of ~ 17 000 M⊙ is needed to repro- in space according to a mass function duce the data, while the velocity dis (i.e., luminosities) and are assigned veloc- persion profile in the core of NGC 2808

24 The Messenger 147 – March 2012 Astronomical Science

The Gaia-ESO Public Spectroscopic Survey

Gerry Gilmore1,* 14 INAF–Osservatorio di Padova, Italy A. Klutsch67, J. Knude68, A. Koch38, O. Kochukhov48, 2,* 15 M. Kontizas69, S. Koposov1, A. Korn48, P. Koubsky62, Sofia Randich Instituto de Astrofisica de Andalucia- 70 5 65 3,+ A. Lanzafame , R. Lallement , P. de Laverny , F. Martin Asplund CSIC, Granada, Spain van Leeuwen1, B. Lemasle21, G. Lewis31, K. Lind3, H. 4,+ 16 James Binney Istituto Astrofisica de Canarias, Tenerife, P. E. Lindstrom68, A. Lobel58, J. Lopez Santiago67, P. Piercarlo Bonifacio 5,+ Spain Lucas6, H. Ludwig33, T. Lueftinger20, L. Magrini2, J. 6,+ 17 Maiz Apellaniz17, J. Maldonado67, G. Marconi24, A. Janet Drew Royal Observatory of Belgium, Brussels, 3 24 56 7, + Marino , C. Martayan , I. Martinez-Valpuesta , Sophia Feltzing Belgium G. Matijevic57, R. McMahon1, S. Messina51, M. 8,+ 18 Annette Ferguson INAF–Osservatorio di Bologna, Italy Meyer49, A. Miglio58, S. Mikolaitis26, I. Minchev42, D. Rob Jeffries 9,+ 19 Dept. of Physics and Astronomy, Minniti71, A. Moitinho72, Y. Momany24, L. Monaco24, 10, + M. Montalto36, M.J. Monteiro36, R. Monier73, D. Giusi Micela University of Uppsala, Sweden 67 74 34 58 11, + 20 Montes , A. Mora , E. Moraux , T. Morel , N. Ignacio Negueruela Dipartimento di Fisica e Astronomia, Mowlavi75, A. Mucciarelli19, U. Munari14, R. 12,+ Timo Prusti Università di Catania, Italy Napiwotzki6, N. Nardetto65, T. Naylor76, Y. Naze58, Hans-Walter Rix13,+ 21 Institut für Astronomie, Universität G. Nelemans77, S. Okamoto78, S. Ortolani79, G. 14,+ Pace36, F. Palla2, J. Palous62, E. Pancino35, R. Antonella Vallenari Wien, Austria 49 20 25 61 15, ‡ 22 Parker , E. Paunzen , J. Penarrubia , I. Pillitteri , Emilio Alfaro Observatoire de la Côte d’Azur, Nice, G. Piotto14, H. Posbic5, L. Prisinzano10, E. Puzeras26, 16, ‡ Carlos Allende-Prieto France A. Quirrenbach33, S. Ragaini19, J. Read49, M. Read8, Carine Babusiaux 5,‡ 23 ESO A. Recio-Blanco65, C. Reyle80, J. De Ridder15, N. 7, ‡ 24 Robichon5, A. Robin80, S. Roeser33, D. Romano35, Thomas Bensby Institut d’Astronomie et d’Astrophysique, 5 3 62 6 17, ‡ F. Royer , G. Ruchti , A. Ruzicka , S. Ryan , N. Ronny Blomme Université Libre de Brussels, Belgium Ryde7, G. Sacco81, N. Santos36, J. Sanz Forcada39, 18, ‡ * Angela Bragaglia Co-PI L. M. Sarro Baro82, L. Sbordone43, E. Schilbach33, Ettore Flaccomio10, ‡ + Steering Committee member S. Schmeja33, O. Schnurr42, R. Schoenrich3, R.-D. 5,‡ ‡ Scholz42, G. Seabroke45, S. Sharma31, G. De Silva44, Patrick François Working Group coordinator 64 78 39 14 1, ‡ R. Smiljanic , M. Smith , E. Solano , R. Sordo , Mike Irwin C. Soubiran83, S. Sousa36, A. Spagna84, M. Steffen42, 1, ‡ Sergey Koposov M. Steinmetz42, B. Stelzer10, E. Stempels48, H. Andreas Korn19, ‡ The Gaia-ESO Survey Team Tabernero67, G. Tautvaisiene26, F. Thevenin65, J. 20,‡ Co-PIs: G. Gilmore1, S. Randich 2 Torra 23, M. Tosi35, E. Tolstoy21, C. Turon5, M. Alessandro Lanzafame 3 4 5 61 1 33 65 17, ‡ CoIs: M. Asplund , J. Binney , P. Bonifacio , J. Walker , N. Walton , J. Wambsganss , C. Worley , Elena Pancino Drew 6, S. Feltzing7, A. Ferguson 8, R. Jeffries 9, G. K. Venn85, J. Vink86, R. Wyse87, S. Zaggia14, W. 21, ‡ Ernst Paunzen Micela10, I. Negueruela11, T. Prusti12, H.-W. Rix13, A. Zeilinger20, M. Zoccali71, J. Zorec88, D. Zucker89, Alejandra Recio-Blanco 22,‡ Vallenari14, D. Aden7, C. Aerts15, L. Affer10, J.-M. T. Zwitter57 2,‡ Alcala16, E. Alfaro17, C. Allende Prieto18, G. Altavilla19, Giuseppe Sacco 20 21 5 22 23,‡ J. Alves , T. Antoja , F. Arenou , C. Argiroffi , A. Rodolfo Smiljanic Asensio Ramos18, C. Babusiaux5, C. Bailer-Jones13, Institutes: 1IoA; 2 INAF–Obs. Arcetri; 3 MPA; 4 Univ. 24,‡ Sophie Van Eck L. Balaguer-Nunez23, A. Bayo24, B. Barbuy25, G. Oxford; 5 Obs. Paris; 6 Univ. Hertforshire; 7 Lund Univ; Nicholas Walton1, ‡ Barisevicius26, D. Barrado y Navascues 27, C. 8 Univ. Edinburgh; 9 Univ. Keele; 10 Obs. Palermo; Battistini7, I. Bellas Velidis28, M. Bellazzini29, V. 11 Univ. de Alicante; 12 ESTEC; 13 MPIA; 14 INAF–Obs. Belokurov1, T. Bensby7, M. Bergemann3, G. Bertelli14, Padova; 15 Kath. Univ. Leuven; 16 INAF–Obs. K. Biazzo16, O. Bienayme30, J. Bland-Hawthorn31, R. Capodimonte; 17 IAA-CSIC; 18 IAC; 19 Univ. Bologna; 1 Institute of Astronomy, University of Blomme32, C. Boeche33, S. Bonito10, S. Boudreault18, 20 Univ. Vienna; 21 Kapteyn Inst.; 22 Univ. Palermo; Cambridge, United Kingdom J. Bouvier34, A. Bragaglia35, I. Brandao36, A. Brown37, 23 Univ. Barcelona; 24 ESO Santiago; 25 Univ. Granada; 12 38 39 26 27 2 INAF–Osservatorio Astrofisico di J. de Bruijne , M. Burleigh , J. Caballero , E. Inst. Theo Phys & Astro., Lithuania; Calar Alto Caffau33, F. Calura40, R. Capuzzo-Dolcetta41, M. Obs.; 28 National Optical Obs., Greece; 29 INAF–Obs. Arcetri, Italy Caramazza10 . G. Carraro24, L. Casagrande3, S. Bologna; 30 Obs. Strasbourg; 31 Univ. Sydney; 32 3 Mount Stromlo Observatory, Australian Casewell38, S. Chapman1, C. Chiappini42, Y. Royal Obs. Belgium; 33 Univ. Heidelberg; 34 Univ. J. National University, Canberra, Australia Chorniy26, N. Christlieb43, M. Cignoni19, G. Cocozza19, Fourier; 35 INAF–Obs. Bologna; 36 CAUP Porto; 37 44 3 13 29 38 39 4 Dept. of Theoretical Physics, University M. Colless , R. Collet , M. Collins , M. Correnti , Univ. Leiden; Univ. Leicester; Centro de Astrobi- E. Covino16, D. Crnojevic8, M. Cropper45, M. ología, Madrid; 40 Univ. Central Lancashire; of Oxford, United Kingdom Cunha36, F. Damiani10, M. David46, A. Delgado17, S. 41 Univ. Rome; 42 AIP Potsdam; 43 Univ. Heidelberg; 5 GEPI, Observatoire de Paris, France Duffau33, S. Van Eck47, B. Edvardsson48, J. Eldridge1, 44 AAO; 45 MSSL, UCL; 46 Univ. Antwerp; 47 ULB, 6 Centre for Astronomy Research, H. Enke42, K. Eriksson48, N.W. Evans1, L. Eyer49, B. Brussels; 48 Uppsala Univ.; 49 ETH Zurich; 50 Univ. 30 50 45 23 51 52 53 University of Hertfordshire, United Famaey , M. Fellhauer , I. Ferreras , F. Figueras , Concepcion; INAF–Obs. Catania; ANU; Univ. G. Fiorentino21, E. Flaccomio10, C. Flynn31, D. Boston; 54 Univ. Warwick; 55 Bamberg Obs.; 56 MPE; Kingdom Folha36, E. Franciosini2, P. Francois5, A. Frasca51, 57 Univ. Ljubliana; 58 Univ. Liege; 59 Karl-Franzens- 7 Lund Observatory, Sweden K. Freeman52, Y. Fremat32, E. Friel53, B. Gaensicke54, Univ.; 60 Univ. Aarhus; 61 CfA; 62 Astr. Inst. Acad. 8 Institute for Astronomy, University of J. Gameiro36, F. Garzon18, S. Geier55, D. Geisler50, Sci., Prague; 63 Univ. Athens; 64 ESO Garching; O. Gerhard56, B. Gibson40, A. Gomboc57, A. Gomez5, 65 OCA Nice; 66 SRON, Utrecht; 67 Univ. Madrid; Edinburgh, United Kingdom 11 18 68 69 70 9 C. Gonzalez-Fernandez , J. Gonzalez Hernandez , Copenhagen Univ. Obs.; Univ. Athens; Univ. Astrophysics Group, University of E. Gosset58, E. Grebel33, R. Greimel59, M. Catania; 71 Univ. Catolica; 72 Univ. Lisbon; 73 Univ. Keele, United Kingdom Groenewegen32, F. Grundahl60, M. Guarcello61, Nice Sofia Ant.; 74 ESAC; 75 Obs. de Geneve; 76 Univ. 10 INAF–Osservatorio Astronomico di B. Gustafsson48, P. Hadrava62, D. Hatzidimitriou63, Exeter; 77 Univ. Nijmegen; 78 KIAA, Beijing; 79 Univ. N. Hambly8, P. Hammersley64, C. Hansen33, M. Padova; 80 Obs. Besancon; 81 Rochester Inst. Palermo, Italy 5 55 48 14 82 83 84 11 Haywood , U. Heber , U. Heiter , E. Held , A. Technology; UNED, Madrid; Univ. Bordeaux; Departamento de Fisica, Universidad Helmi21, G. Hensler20, A. Herrero18, V. Hill65, S. INAF–Obs. Torrino; 85 Univ. Victoria; 86 Armagh Obs.; de Alicante, Spain Hodgkin1, N. Huelamo39, A. Huxor33, R. Ibata30, M. 87 Johns Hopkins Univ.; 88 IAP; 89 MacQuarie Univ. 12 ESTEC, ESA, the Netherlands Irwin1, R. Jackson9, R. de Jong42, P. Jonker66, S. 33 23 47 5 13 Max-Planck Institut für Astronomy, Jordan , C. Jordi , A. Jorissen , D. Katz , D. Kawata45, S. Keller52, N. Kharchenko42, R. Klement13, Heidelberg, Germany

The Messenger 147 – March 2012 25 Astronomical Science Gilmore G. et al., The Gaia-ESO Public Spectroscopic Survey

The Gaia-ESO Public Spectroscopic community in a favourable situation ... motions, and improved astrophysical Survey has begun and will obtain high and would go a long way towards gener- parameters for each star, the survey will quality spectroscopy of some 100 000 ating the data required to complement quantify the formation history and evolu- Milky Way stars, in the field and in Gaia if the surveys begin soon”. tion of young, mature and ancient Galac- open clusters, down to magnitude 19, tic populations. The precision astrometry systematically covering all the major That recommendation led, via a process will be provided by the Gaia “Galactic components of the Milky Way. This sur- involving Letters of Intent, review, and census”, with the first astrometric data vey will provide the first homogeneous preliminary selection, to a 300-author release likely to occur in 2016, in time for overview of the distributions of kine proposal for the Gaia-ESO Public Spec- the full analysis of the complete Gaia-ESO matics and chemical element abun- troscopic Survey, a 300-night survey Survey data. dances in the Galaxy. The motivation, of all Galactic Stellar Populations, using organisation and implementation of the FLAMES (both GIRAFFE and UVES) on The Gaia-ESO Survey is among the Gaia-ESO Survey are described, em the VLT’s Unit Telescope 2 (UT2). Follow- largest and most ambitious ground-based phasising the complementarity with the ing the review and approval of the pro- surveys ever attempted by European as ESA Gaia mission. Spectra from the posal, and the development of a detailed tronomy. The Survey consortium involves very first observing run of the survey Survey Management Plan agreed between some 300 scientists in over 90 institu- are presented. ESO and the two Co-PIs, the Gaia-ESO tions (see the list of team members). This Survey began taking data on the night of large allocation of telescope time, which 31 December 2011. followed a very detailed scientific and “Europe has led the way in Galactic re managerial peer review, is a robust search as regards astrometry and spec- This ambitious survey, of similar scale to measure of the strength and originality of troscopy, and is on the brink of taking the Public Surveys on VISTA and VST, is the scientific case, the high legacy value the lead in photometry: ESA’s Hipparcos very clearly the culmination of many years of the Survey dataset, the appropriate- mission pioneered space astrometry of hard work, initiative, planning and ness of the methodology being utilised, and paved the way for the ambitious Gaia dedication by very many people, from and the project implementation and man- mission, which will perform the first paral- the writing of the science strategy to the agement structure. There are two sur- lax survey down to magnitude V = 20 in spectrum analysis software. With the vey Co-PIs, Gerry Gilmore and Sofia parallel with a complete characterisation European Space Agency Gaia mission Randich, leading the Milky Way and cali- of each observed object; ESO’s innova- due for launch in 2013, Europe is indeed bration aspects, and star cluster aspects, tive telescopes (NTT and VLT) coupled to well on the way to scientific leadership in respectively. The important synergy leading capabilities in the construction quantitative studies of the formation and from covering all Galactic components is of multi-object spectrographs have yielded evolution of the Milky Way and its com- a joint responsibility and opportunity. detailed stellar abundances of faint ponents. The Gaia-ESO Survey offers the stars; ESO is about to start massive pro- opportunity to meet that challenge. grammes of optical/near-IR photometry Gaia-ESO Survey scientific background with two dedicated survey telescopes (VISTA and VST).” That impressive long What is the Gaia-ESO Survey? Understanding how galaxies actually form sentence introduced the Messenger and evolve within our ΛCDM (Lambda article (Turon et al., 2008b) describing the The Gaia-ESO Public Spectroscopic Cold Dark Matter) Universe, and how work of the ESA–ESO Working Group Survey employs the VLT FLAMES instru- their component stars and stellar popula- on Galactic Populations, Chemistry and ment for high quality spectroscopy of tions form and evolve, continues to be Dynamics (Turon et al., 2008a). The some 100 000 stars in the Milky Way. an enormous challenge. Extant simula- same Messenger issue reported on the With well-defined samples, based primar- tions of the aggregation of cold dark mat- ASTRONET Infrastructure Roadmap: A ily on current VISTA photometry for the ter (CDM) suggest that galaxies grow Twenty Year Strategy for European As field stars, and on the Two Micron All Sky through a sequence of merger and ac tronomy (Bode & Monnet, 2008), which Survey (2MASS) and a variety of photo- cretion events. Most events involve accre- concluded “among medium-scale invest- metric surveys of open clusters, the sur- tion of an object that is so small that it ments, science analysis and exploitation vey will quantify the kinematic multi- barely perturbs the system, some events for the approved Horizon 2000 Plus astro- chemical element abundance distribution involve an object large enough to pro- metric mission Gaia was judged most functions of the Milky Way Bulge, the duce a mild perturbation, and a handful important”. The ESO community and thick Disc, the thin Disc, and the Halo of events involve an object that causes ESO’s Scientific Technical Committee stellar components, as well as a very sig- a major convulsion. Exactly how these (STC) have continued the theme, leading nificant sample of 100 open clusters, events impact on a galaxy cannot be pre- to an ESO Workshop on Wide-field Spec- covering all accessible cluster ages and dicted at this time because the extremely troscopic Surveys, held in March 2009 stellar masses. This alone will revolu complex physics of baryons cannot (Melnick et al., 2009). This meeting con- tionise knowledge of Galactic and stellar be reliably simulated: at a minimum it cluded that a large public spectroscopic evolution. When combined with preci- involves interstellar chemistry, magnetic survey, using current ESO VLT instru sion astrometry, delivering accurate dis- reconnection, radiative transfer in the mentation, “could place the European tances, 3D spatial distributions, 3D space presence of spectral lines and significant

26 The Messenger 147 – March 2012 velocity gradients, thermonuclear fusion, Figure 1. A colour– neutron absorption, neutrino scattering, magnitude diagram based on the Hipparcos radioactive decay, cosmic ray accel –4 re-analysis by Floor eration and diffusion. Theoretical models van Leeuwen, of nearby of galaxy formation rely more heavily on precise luminosity and phenomenological models than on physi- colour data. The open cluster data are colour- cal theory. Thus, these models require –2 coded by age, blue calibration with well-studied (nearby) test being younger, red cases. For example, star formation older. Local field stars involves turbulence, magnetic reconnec- are in grey. tion, collisionless shocks, and radiative 0 transfer through a turbulent medium. Similarly, the treatment of convection, mixing, equations of state at high density, opacities, rotation and magnetic fields 2 can all significantly affect stellar luminosi- P ties, radii, and lifetimes at different evolu- MH tionary phases. We are far from being able to simulate the coupled evolution of 4 CDM and baryons from ab initio physics.

Observations are crucial to learning how 6 galaxies and stars were formed and evolved to their present structure. Obser- vations of objects at high redshifts and long lookback times are important for this 8 endeavour, as is the detailed examination of our Galaxy, because such “near-field cosmology” gives insights into key processes that cannot be obtained by study- 10 ing faint, poorly resolved objects with uncertain features. Just as the history of 0 0.5 11.5 life was deduced by examining rocks, we B–V expect to deduce the history of the Gal- axy by examining stars. Stars record the clouds, and the period in which a core astrophysics hinges on these crucial past in their ages, compositions and kin- grows by accretion. We know that out- comparisons between cluster observa- ematics. For example, individual accre- flows of various types disperse most tions and the predictions of the models. tion and cluster dissolution events can be of the gas of a cloud, and that the great inferred by detecting stellar streams from majority of groups of young stars then Figure 1 illustrates the state-of-the-art accurate phase-space positions. Corre quickly disperse. More populous groups colour–magnitude diagram based on lations between the chemical composi- survive the dispersal as open clusters, a re-analysis of Hipparcos data (van tions and kinematics of field stars will and subsequently disperse through a Leeuwen, 2007) for nearby stars. The enable us to deduce the history of star combination of internal mass loss, two- rich information content of precise stellar formation and even the past dynamics of body scattering off other members of astrometric, kinematic, and chemical the Disc. The kinematic structure of the the group, and tidal disturbance by the abundance data for both clusters and Bulge will reveal the relative importance gravitational fields of external objects such field quantifies not only stellar evolution in its formation of disc instability and as giant molecular clouds and spiral arms. models, and their limitations, but also an early major merger. The study of open It is possible that open clusters are the Galactic evolution models, and their limi- clusters is crucial to understanding fun- dominant source of field stars. They trace tations. Adding 100 well-observed clus- damental issues in stellar evolution, the different thin Disc components covering ters, covering and characterising stars star formation process, and the assembly broad age and metallicity intervals, from down to low masses, to this figure will be and evolution of the Milky Way thin Disc. a few Myr up to several Gyr, from 0.3 to a revolution in our knowledge. two times solar abundance. Each cluster Most stars form in associations and clus- provides a snapshot of stellar evolution. ters, rather than singly, so understand- Thus, observations of many clusters Scale of the challenge and specific scien- ing star formation also implies studying at different ages and chemical composi- tific objectives cluster formation. Advances in infrared tions, quantify stellar evolution, allowing astronomy have opened up the study increasingly detailed theoretical models The key to addressing these topics, and of the formation of stellar cores in dark to be tested. Much stellar and Galactic decoding the history of the formation and

The Messenger 147 – March 2012 27 Astronomical Science Gilmore G. et al., The Gaia-ESO Public Spectroscopic Survey

calibration and ESO archive re-analysis to Gaia Gaia-ESO ensure maximum future utility.

Why not just wait for Gaia? 2-D 3-D 5-D 6-D 12+ D The Gaia mission will provide photometry and astrometry of unprecedented pre Proper Astrophysical Position Parallax Spectrum motions parameters cision for most stars brighter than G = 20 mag, and obtain low resolution spectra for most stars brighter than 17th magni- Ultra-precision, Transverse Radial velocity Ages, histories, Distance over years velocities + chemistry astrophysics tude. The first astrometry data release is likely to be in 2016, with spectropho- tometry and stellar parameters to follow Stellar orbits, star formation history, origin of the elements, Galaxy assembly,.... later, and 2021 for the final catalogue. dark matter, cosmological initial conditions, fundamental physics, solar system(s) Crucially, Gaia has limited spectroscopic capabilities and, like all spacecraft, does Figure 2. Diagrammatic representation of the out- Gaia-ESO Survey legacy overview not try to compete with large ground- puts of the Gaia and Gaia-ESO surveys, showing based telescopes at what they do best. how they are complementary. This VLT survey delivers the data to sup- evolution of the Galaxy and its compo- port a wide variety of studies of stellar A convenient way of picturing the Gaia– nents, involves three aspects: chemical populations, the evolution of dynamical ground complementarity is to look at element mapping, which quantifies systems, and stellar evolution. The Sur- the dimensionality of data which can be timescales, mixing and accretion length vey will complement Gaia by using the obtained on an astrophysical object. scales, star formation histories, nucleo- GIRAFFE+ UVES spectrographs to meas- Larger amounts of information of higher synthesis and internal processes in ure detailed abundances for at least quality are the goal, to increase under- stars; spatial distributions, which relate 12 elements (Na, Mg, Si, Ca, Ti, V, Cr, Mn, standing. Figure 2 gives a cartoon view to structures and gradients; and kinemat- Fe, Co, Sr, Zr, Ba) in up to 10 000 field of this information set. There are four ics, which relates to both the felt, but stars with V < 15 mag and for several ad basic thresholds which we must pass. unseen, dark matter, and dynamical his- ditional elements (including Li) for more The first is to know a source exists, its tories of clusters and merger events. metal-rich cluster stars. Depending position, and basic photometric data. With Gaia, and stellar models calibrated on target signal-to-noise (S/N) and astro- Photometric surveys, such as those on clusters, one will also add ages for physical parameters, the data will typically underway at VISTA and VST will deliver (slightly evolved) field stars, for the first probe the fundamental nucleosynthetic this information. The second is to add time. Manifestly, a spectroscopic survey channels: nuclear statistical equilibrium the time domain — motions, including returning data for very large samples is (through V, Cr, Mn, Fe, Co), and alpha- parallax, providing distances and speeds. required to define with high statistical sig- chain (through Si, Ca, Ti). The radial Here Gaia will be revolutionary. The nificance all these distribution functions velocity precision for this sample will be third threshold is radial velocity, turning and their spatial and temporal gradients. 0.1 to 5 kms–1, depending on target, motions into orbits. While Gaia will pro- with, in each case, the measurement pre- vide radial velocities, the magnitude limit The Gaia-ESO Survey is that survey. cision being that required for the rele- is three magnitudes brighter than that Moreover, it will also be the first survey vant astrophysical analysis. The data will of the astrometry and the precision is yielding a homogeneous dataset for resolve the full phase-space distribu- much below that of proper motions. Here large samples of both field and cluster tions for large stellar samples in clusters, the Gaia-ESO will be crucial to supple- stars, providing unique added value. The making it possible to identify, on both ment Gaia spectroscopy. The fourth specific top-level scientific goals it will chemical and kinematic grounds, sub- threshold is chemistry, and astrophysical allow to be addressed include: structures that bear witness to particular parameters. These latter two both re- – Open cluster formation, evolution, and merger or starburst events, and to fol- quire spectroscopy, which is the key disruption; low the dissolution of clusters and the information from the Gaia-ESO Survey. – Calibration of the complex physics that Galactic migration of field stars. affects stellar evolution; – Quantitative studies of Halo substruc- The survey will also supply homogene- Gaia-ESO Survey samples and observa- ture, dark matter, and rare stars; ously determined chemical abundances, tional strategy – Nature of the Bulge; rotation rates and diagnostics of mag- – Origin of the thick Disc; netic activity and accretion, for large The Gaia-ESO Survey observing strat- – Formation, evolution, structure of the samples of stars in clusters with precise egy has been designed to deliver the thin Disc; distances, which can be used to chal- top-level survey goals. The Galactic inner – Kinematic multi-element distribution lenge stellar evolution models. Consider- and outer Bulge will be surveyed, as function in the Solar Neighbourhood. able effort will be invested in abundance will be the inner and outer thick and thin

28 The Messenger 147 – March 2012 Gaia-ESO data ﬂow–conceptual, Working Groups (WGs) identiﬁed to be used for accurate multi-element abundances. Target selection Observing Clusters Field stars Calibrations Block (OB) preparation WG 1, 2, 4, 6 WG 3, 6 WG 5 For the field survey, two GIRAFFE high resolution setups are used, HR10 and

OB transfer to ESO; Observing (WG 0); data from archive to PIs Su HR21, which include a large enough num- 18 rv

, ber of Fe i and Fe ii lines for astrophysi- ey Pr

17 Reduction pipelines WG7 cal parameter determination, along with Radial velocities WG8

og lines of other key elements. The parallel Classiﬁcation WG9 re

e, WG UVES observations will use the 580 nm

First quality control ss setup. For the clusters, and depending on

chiv Monit the specific targets, six GIRAFFE setups ar Spectrum Analyses

d are employed (HR03/05A/06/14A/15N/21). oring an HR03/05A/06/14A contain a large num- e FGK Giraffe FGK UVES PMS OBA Nonstandard ber of spectral features, to be used to WG

rag (10) (11) (12) (13) (14) o derive radial velocities and astrophysical st

Quality Control (QC) QC QC QC 16 parameters of early-type stars. HR15N/21 are instead the most appropriate grat- Data (Iterative) Parameter Homogenization, WG 15 & WG 5 ings for late-type stars; they access a large enough number of lines to derive Value added products, science quality control (consortium) radial velocities, as well as to retrieve key information on the star’s characteristics Value added products, metadata to ESO WG 16, 17 (e.g., temperature, [Li/H], accretion rates,

chromospheric activity, rotation). For Figure 3. Data flow schematic, from the Survey well-defined low latitude sample probes UVES, the 520 nm and 580 nm setups Management Plan, to illustrate the challenges 2–4 kpc, more than a radial scale length. will be used for hot and cool stars, involved in the Gaia-ESO Survey. The logical path flows from pre-observation target selection through In addition, we will allocate 25 % of the respectively. observing at the top, through data processing, fibres to brighter candidate K giants, which data spectrum analysis, astrophysical parameter probe the far outer thick Disc, warp, flare determination, calibration, homogenisation, to deliv- and Monocerus stream, and will deliver Gaia-ESO Survey methodology and ery of science data for verification analysis at the bottom. Infrastructure provision is down the sides, excellent S/N. To quantify thin Disc dy implementation activities being relevant at all stages, as is the survey progress namics, we will target 4–6 fields toI = 19 monitoring, and quality control by the Co-PI teams, mag. in the Plane to test spiral arm/bar The Gaia-ESO Survey is a very large preparatory for public data release. dynamics obtaining several thousand project, with substantial resource com- radial velocities per line of sight. We will mitments in terms of telescope access. dedicate UVES parallels for the field sur- The greatest cost, and opportunity, is Discs, the Halo and known Halo streams. veys to an unbiased sample of 5000 FG of course the time of the 300 scientists Particular focus will be put on the local stars within 2 kpc of the Sun. dedicated to this project over the next thin Disc, as this study both complements five years. To guarantee that this resource Gaia astrometry and will benefit most Cluster selection is optimised to fine- is utilised with maximal efficiency and from the high precision Gaia data. More sample the age–[Fe/H]–Galactocentric effectiveness, we have developed a very specifically, prime GIRAFFE targets in distance–mass parameter space. Clus- detailed plan, clarifying every stage of the Bulge are K giants, which dominate ters in all phases of evolution (except information flow, decision dependency, the relevant colour–magnitude diagram embedded), with ages from about 1 Myr data processing, information storage, and selection. Primary targets in the Halo and up to 10 Gyr will be included, sampling provision of documented data for team thick Disc are r = 17–18 mag. F stars, different environments and star formation scientific analysis. This involved a with the bluer, fainter F stars probing the conditions. This will provide sufficient 42-page science case, supplemented by Halo and brighter, redder F stars probing statistics to explore the dynamical evolu- a 25-page management plan, describing the thick Disc. Sloan Digital Sky Survey tion of clusters; the same sample will map every stage of the project implementa- (SDSS) photometry shows a clear thick stellar evolution as a function of metal tion, from science goal through detailed

Disc/Halo transition at 17 < r < 18 and licity for 0.1 < M/M⊙ <100, even for short- target selection, data processing, and 0.2 < g – r < 0.4 — and we use the equiv- lived evolutionary phases, and provide readiness for scientific analysis. The sci- alent selection from VISTA near-infrared a population large enough to throughly ence plan was reviewed and approved by photometry. In fields crossing known Halo investigate metallicity as a function of a special ESO-organised science strat- streams (e.g., Sagittarius), K giant candi- Galactocentric radius and age. In all clus- egy panel, and by the ESO Time Alloca- dates will be included in the sample. ters GIRAFFE will be used to target faint tion system. The management plan was cluster members (down to V = 19), while reviewed by ESO and agreed after minor Outer thick Disc fields will have distant parallel UVES fibres will be fed with iteration. These documents form a mem- F stars as prime targets, like the Halo. This brighter or key objects (down to V = 16.5), orandum of understanding between ESO

The Messenger 147 – March 2012 29 Astronomical Science Gilmore G. et al., The Gaia-ESO Public Spectroscopic Survey

Figure 4. GIRAFFE spectra of a 5000 Milky Way star in the outer thick Disc l (grating setting HR21, upper panel) 4000 and a member of the young cluster γ xe 3000 pi Velorum (setting HR15N, lower panel). 2000

Note the strong Hα emission and e–/ 1000 lithium 6708 Å line in the latter, both 0 indicators of youth. 8500 8600 8700 8800 8900 Wavelength (Å)

l 2.0 × 10 4

xe 1.5 × 10

pi 1.0 × 104 3

e–/ 5.0 × 10 0 6500 6600 6700 6800 Wavelength (Å) Figure 5. Left panel: UVES spectra are shown of a member of γ Velorum around Hα (upper) and the lithium line (bottom). Right panel: UVES spectra of a Milky Way field star in the Hα (upper) and Hβ (lower) spectral regions.

0.10 0.08

0.08 0.06

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0.00 0.00 6500 6520 6540 6560 6580 6600 6500 6520 6540 6560 6580 6600 Wavelength (Å) Wavelength (Å)

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30 The Messenger 147 – March 2012 and the Co-PIs on Survey delivery. They dances, with corresponding random ard star, real survey data soon followed. are available on the survey wiki1 and and systematic errors, and an explicit During the first run 12 different fields in the (forthcoming) web page2. analysis of the effect of alternative analy- 10 Myr cluster γ Velorum were observed, sis assumptions. All these results will along with three fields in the outer thick A Survey Consortium Working Group be archived for later analysis, both in the Disc. Examples of GIRAFFE and UVES structure has been created to match operational database, and the Survey spectra are shown in Figures 4 and 5. the information and requirements flow, archive for later public analysis. All survey from the scientific context which defines products will be delivered to the ESO source selection, through selection, archive. Prospects observation, data reduction, classifica- tion, spectrum analysis, astrophysical The big themes in European astronomy parameter determination, and collation Complementary activities require both space and ground-based of all the information necessary for sci- observations. ence verification analysis (see Figure 3). Given the outstanding range of science The survey activities are structured into opportunities in near-field cosmology, In the field of Milky Way studies, the key 18 Working Groups, one for each level it is not surprising that Galactic surveys recommendations of the joint ESA–ESO of critical specialist activity, each with are a major research activity globally. working group (chaired by Catherine an identified coordinator, remit, require- One of these, AEGIS, using the Australian Turon) can be summarised in two words ments, and deliverables. AAO 2dF facility, is coordinated with covering both space and ground: “Gaia” the Milky Way field part of Gaia-ESO, with and “spectroscopy”. The planned spec- A 19th Working Group dedicated to shared photometric targets, and closely troscopic data products from the Gaia- communications is also included. The coordinated follow-up science planning. ESO Survey will all be available to the Working Group coordinators report to AEGIS, which targets candidate Halo community roughly at the same time as the Co-PIs, who are advised by a Steer- stars identified from the SkyMapper pho- the first intermediate Gaia catalogue, ing Group, which acts as the project tometric survey, aims to observe the rare expected around 2016. Future dedicated management board. The Steering Group relatively bright metal-poor stars, to add survey spectroscopy facilities are under members act to assist the Co-PIs in statistical weight in the wings of the Gaia- study to allow Europe to carry the torch supporting the consortium activities. The ESO distribution function. The AEGIS PI forward in years to come, learning from Steering Committee and Working Group is Stefan Keller at the Australian National this first effort. The European scientific leads are identified as co-authors of this University (ANU). A second comple community has an enormous opportunity article. There are many more workers mentary survey is the RAdial Velocity to address a multitude of Galactic astron- than there are managers — which is why Experiment (RAVE)3: a very-large-number omy topics with combined spectroscopic the survey works! survey, albeit restricted to low resolution and Gaia data. calcium triplet spectra, and limited to At the heart of the survey data pro stars brighter I = 13 mag, brighter than cessing are the spectrum analyses. All the Gaia-ESO bright limit. RAVE kine Acknowledgements extracted spectra are processed through matics are good, and so complemen- Support to the development of the Gaia-ESO Sur- general purpose pipelines, to refine astro- tary analyses of the joint RAVE and Gaia- vey has been provided in part by the European Sci- physical parameters, and deliver ele ESO kinematic samples will be enor- ence Foundation Gaia Research for European mental abundances to a level appropriate mously powerful. The RAVE PI is Matthias Astronomy Training (GREAT-ESF) Research Network 4 for the relevant stellar type and availa- Steinmetz at AIP Potsdam. In order to Programme . ble S/N. Separate pipelines manage, maximise synergy between archive spec- respectively, hot, warm and cool stars, troscopy, the various bright star surveys References as well as pre-main sequence stars, and underway, such as RAVE, or planned, GIRAFFE and UVES spectra. It is a Gaia-ESO, and Gaia itself, are investing Bode, M. & Monnet, G. 2008, The Messenger, 134, 2 Melnick, J. et al. 2009, The Messenger, 136, 64 strength of this Gaia-ESO Survey team considerable effort establishing common Turon, C. et al. 2008a, ESA–ESO Working Group that it includes a majority of Europe’s abundance calibrations between availa- Report on Galactic Populations, Chemistry and spectrum analysis groups, which between ble and planned datasets. This work, Dynamics them have available a wealth of expertise. coordinated by Elena Pancino and Sofia Turon, C. et al. 2008b, The Messenger, 134, 46 van Leeuwen, F. 2007, A&A, 474, 653 All groups have agreed to adopt a fixed Feltzing, should ensure a real long-term set of atomic data and model atmos- legacy from the Gaia-ESO Survey. pheres for the analysis of FGK stars. Very Links considerable coordination between the teams has been underway for some First light! 1 Gaia-ESO Survey wiki page: months. This range of analysis excellence http://great.ast.cam.ac.uk/GESwiki/GESHome 2 Gaia-ESO Survey web page: will be applied to the various stellar and The first observations were obtained on 31 http://www.gaia-eso.eu data types as appropriate. Sanity check- December 2011, by Thomas Bensby and 3 RAVE web page: http://www.rave-survey.org ing will then deliver, for each star target, Christophe Martayan. While the first spec- 4 Homepage of ESF GREAT: http://www.great-esf.eu a “best” set of parameters and abun- trum was, unsurprisingly, a twilight stand-

The Messenger 147 – March 2012 31 Astronomical Science

Teenage Galaxies

Thierry Contini1, 2 galaxies over cosmological timescales. the intergalactic medium through the der- Benoît Epinat1,2,3 Even if these data enabled significant ivation of metallicity gradients. Daniela Vergani4 progress concerning the knowledge of Julien Queyrel 1, 2 the global properties of different galaxy Lidia Tasca 3 populations in different environments, A representative sample of high-z galaxies Philippe Amram 3 more detailed constraints are needed to Bianca Garilli 5 understand the main physical processes The MASSIV sample includes 84 star- Markus Kissler-Patig 6 involved in the formation and evolution forming galaxies drawn from the VIMOS Olivier Le Fèvre 3 of galaxies. Based on observational and/ VLT Deep Survey (VVDS; Le Fèvre et al., Jihane Moultaka1, 2 or theoretical arguments, we know that 2005) in the redshift range 0.9 < z < 2.2. Luigi Paioro 5 galaxy merging is at work in the growth The main advantage of selecting galax- Laurence Tresse 3 of galaxies. Cold gas accretion along ies from the VVDS is that it is a complete Carlos Lopez-Sanjuan3 cosmic filaments has also been empha- magnitude-selected survey avoiding the Enrique Perez-Montero7 sised as an efficient process for sustain- biases linked to a priori colour selection Valentin Perret 3 ing high star formation rates and explain- techniques. This unique sample of more Frédéric Bournaud 8 ing the clumpy nature of high-redshift than 4400 galaxies, with accurate and Claire Divoy 1, 2 galaxy discs. However, observational sig- secure spectroscopic redshifts between natures for cold accretion are still being 0.9 and 2, contains both star-forming debated, and we do not know yet the and passive galaxies distributed over a 1 Institut de Recherche en Astrophysique cosmic epoch during which either one of wide range of stellar masses and star et Planétologie (IRAP), CNRS, Toulouse, these two processes (mergers and cold formation rates. It enabled us to easily France accretion) was dominant. define volume-limited subsamples of 2 IRAP, Université de Toulouse, UPS-OMP, high-z galaxies for integral field spectro- Toulouse, France Spatially-resolved observations of high- scopic follow-up. 3 Laboratoire d’Astrophysique de redshift galaxies have begun to give some Marseille, Université d’Aix-Marseille & clues that help to answer this question, Three selection criteria were applied to CNRS, Marseille, France as they allow us to probe both the internal selected MASSIV targets inside the 4 INAF–Instituto di Astrofísica Spaziale e properties (kinematics, distribution of VVDS. First, galaxies were selected to be Fisica Cosmica Bologna & Osservatorio metals, etc.) and close environment of star-forming, in order to ensure that the Astronomico di Bologna, Italy distant galaxies. However, most of the brightest rest-frame optical emission lines 5 INAF–Instituto di Astrofísica Spaziale e previous surveys have concentrated their (mainly Hα and [N ii] 6584 Å, or in a few Fisica Cosmica Milano, Italy efforts on the z > 2 Universe (e.g., SINS; cases [O iii] 5007 Å) used to probe kine- 6 ESO Förster Schreiber et al., 2009; 2011) or on matics and metallicity are observed 7 Instituto de Astrofísica de Andalucia, lower redshifts z < 0.8 (IMAGES; Puech with SINFONI in the near-infrared J- or Granada, Spain et al., 2008). Much less is known of the H-bands. The selection of star-forming 8 Laboratoire AIM Paris-Saclay, z ~ 1−2 redshift range, which corresponds galaxies up to redshift z ~ 1.5 (75 % CEA/IRFU/SAp, Gif-sur-Yvette, France to a lookback time of 8 to 10 billion years. of MASSIV galaxies) was based on the However, we know that at the peak of strength and equivalent width of the cosmic star formation activity galaxies [O ii] 3727 Å, emission line measured on The early growth stages of galaxies are experience major transformations. Is cold VIMOS spectra (see Figure 1). Galaxies at still poorly understood. The aim of the gas accretion still an efficient process higher redshift (21 objects with z > 1.5) MASSIV survey is to better understand for assembling galaxies or are major were selected to be star-forming on the the key processes that govern the evo- mergers predominant, as seems to be the basis of their restframe ultraviolet contin- lution of galaxies at redshifts z ~ 1–2, case at later epochs? uum and/or absorption lines. a particularly turbulent period similar to the teenage years. This paper presents MASSIV (Mass Assembly Survey with We further restricted the sample by this ambitious survey, together with the SINFONI in VVDS) tackles this issue by taking into account two important obser- main results obtained so far from this surveying a representative sample of vational constraints. The expected emis- ESO Large Programme with SINFONI at star-forming galaxies in the redshift range sion line to be observed with SINFONI the VLT. z ~ 1−2 (Contini et al., 2012). With the (mainly Hα) had to fall far away from the detailed information provided by SINFONI numerous bright OH night-sky lines, on individual galaxies, the key science restricting considerably the observable The details of the evolution processes goals of the MASSIV survey are to investi- redshift domain. Moreover, 90 % of that drive galaxy assembly are still largely gate: (1) the nature of the dynamical sup- MASSIV galaxies were selected to be fur- unconstrained. During the last decade, port (rotation vs. dispersion) of high-z ther observable at higher spatial reso major spectroscopic and multi-wavelength galaxies; (2) the respective role of merg- lution with the adaptive optics system of photometric surveys explored the high- ers (minor and/or major) and gas accre- SINFONI or with future imaging/spectro- redshift Universe in depth, enabling us to tion in galaxy growth; and (3) the process scopic facilities. In these cases, a bright follow the evolution of large numbers of of gas exchange (inflows/outflows) with star close enough to the target is needed

32 The Messenger 147 – March 2012 , 22(5 Y (, &$2 2(-2 Y .2(1(2 +2# , 9$

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Figure 1. Selection of MASSIV star-forming galaxies of galaxies in the stellar mass regime Figure 2. Relation between star formation rate and in the VVDS sample (small grey symbols). The 109–1011 M down to a relatively low star stellar mass for high-z galaxies is shown. The dashed line indicates the selection box based on ⊙ MASSIV sample (black filled squares) is compared [O ii] 3727 Å, emission-line equivalent width, used as formation level (Contini et al., 2012). with other major integral field spectroscopic surveys a proxy for star formation. The 63 galaxies in the of distant galaxies: IMAGES (z ~ 0.4−0.75, blue cir- redshift range z ~ 0.9–1.5 selected for SINFONI The integral field spectroscopic obser cles), SINS (z ~ 1.4−2.6, magenta triangles), OSIRIS observations are indicated by large blue squares. vations of the MASSIV sample were per- (z ~ 1.5−3.3, green crosses), and LSD/AMAZE (z ~ 2.6−3.8, red asterisks). The black lines represent formed with SINFONI mounted at the the empirical relations between star formation rate Cassegrain focus of the Very Large Tele- and stellar mass for different redshifts between z = 0 for the zero order tip-tilt corrections. All in scope (VLT) Unit Telescope 4. Most of and z = 3 (Bouché et al., 2010). all, starting from a parent sample of more the data (90 %) were collected in service than 4400 VVDS galaxies at z = 0.9–2.0, mode during several observing periods only ~ 10 % (~ 540 galaxies) satisfy the between April 2007 and January 2011, onds to take full advantage of the gain in above-mentioned criteria. The 84 galax- as part of the ESO Large Programme angular resolution provided by the adap- ies defining the MASSIV sample were 179-A.0823. However, 11 galaxies of the tive optics. For the four other targets, selected randomly from these targets. MASSIV sample (including three with we used the larger pixel scale as a trade- duplicated observations) were observed off between enhanced angular resolution The main advantage of MASSIV, com- during two pilot runs with SINFONI in and sensitivity (see Contini et al. [2012] pared to other high-z integral field spec- September 2005 and November 2006 for a detailed discussion). The observing troscopic surveys, is its representative- (performed in visitor mode). conditions were generally good, with ness for galaxies with star formation rates clear-to-photometric sky transparency as low as 5 M⊙/yr. In contrast, surveys To map the Hα, [N ii] 6584 Å, and [S ii] and typical seeing of 0.5−0.8 arcseconds like SINS (e.g., Förster Schreiber et al., 6717,6731 Å, emission lines, or [O iii] at near-infrared wavelengths. The total 2009), OSIRIS (e.g., Law et al., 2007) and 5007 Å, and Hβ for four galaxies of the on-source integration times ranged on LSD/AMAZE (e.g., Gnerucci et al., 2011; MASSIV sample, we used the J or H grat- average from 80 to 120 minutes. Mailoino et al., 2010) target galaxies ings, depending on the redshift of the selected in various, and hence heteroge- sources. The vast majority of the observa The first results of the MASSIV survey, neous, colour-selected samples (Lyman- tions (74 galaxies) were carried out in recently published in Epinat et al. (2012), break galaxies, BzK, etc.). These surveys seeing-limited mode with the largest pixel Queyrel et al. (2012), and Vergani et al. mainly probe galaxies at a relatively scale of 0.125 arcseconds/pixel, giving (2012), are based on the first epoch sam- higher star formation level for a given stel- a field of view (FoV) of 8 by 8 arcseconds. ple. It contains 49 galaxies in the red- lar mass (as shown by the comparison However, we were able to observe 11 gal- shift range 0.9 < z < 1.6 that were ob in Figure 2). With a selection based mainly axies at higher spatial resolution with served before January 2010. The fully on the [O ii] 3727 Å, emission line, adaptive optics. For seven of these, we calibrated datacubes and derived proper- MASSIV is essentially a flux-limited sam- selected the intermediate 0.05 arcsecond/ ties of this sample are already publicly ple which provides a fair representation pixel scale with FoV of 3.2 by 3.2 arcsec- available through the MASSIV database1.

The Messenger 147 – March 2012 33 Astronomical Science Contini T. et al., Teenage Galaxies

Mergers and discs at z ~ 1.2 France Hawaii Telescope (CFHT) Legacy in the velocity fields, whereas the identi Survey I-band images, making the fication of interacting systems in MASSIV The ionised gas kinematics of MASSIV assumption that the stars and the ionised is based essentially on the detection of galaxies was studied through the bright- gas follow a common distribution. several star-forming components inside est emission line available in the SINFONI ongoing mergers or of companions spectra: mainly Hα, or [O iii] 5007 Å in a Using this information, 46 MASSIV galax- around the main galaxy. The proportion few cases. Among the various dynamical ies have been classified into four broad of mergers in MASSIV is thus a lower states of galaxies, the easiest to probe classes (see Figure 3), based on their kin- limit, as it could well be that a significant is the rotating disc. We have thus tested ematics (rotating discs or not) and close number of apparently isolated non-rotating for the presence of a rotating disc in each environment (isolated galaxies vs. inter- MASSIV galaxy and then recovered the acting/merging systems). fundamental dynamical parameters within Figure 3. Velocity fields for 42 star-forming galaxies at z ~ 0.9–1.6 observed with SINFONI as part of this hypothesis (Epinat et al., 2012). How- The fraction of interacting/merging sys- the MASSIV survey. Blue to red colours correspond ever, some parameters, such as the rota- tems in the MASSIV sample is at least to regions of the galaxies that are approaching tion velocity, are difficult to constrain from ~ 30 % (Epinat et al., 2012). At first glance, and receding relative to their systemic velocity. All the kinematic modelling alone. In order this fraction looks comparable to that galaxies are shown on the same angular scale indicated by the horizontal bar (1 arcsecond ~ 8 kilo to reduce the number of free parameters, found at z ~ 2 in the SINS sample. How- parsecs at z ~ 1–2). Galaxies are classified into four we first estimated the centre and the ever, SINS mergers are identified mainly broad classes based on their kinematics (top: rotat- inclination of the galaxies from their mor- using kinemetry, a technique based ing discs, bottom: non-rotating objects) and close phology as measured on the Canada on the degree of perturbation observed environment (left: isolated galaxies, right: interacting/ merging systems), demarcated by dashed lines.

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34 The Messenger 147 – March 2012 1012 Figure 4. Relation et al., 2012). At high redshift, we think between stellar mass that mass assembly driven by cold flows z = 1.0 and velocity (rotation + z = 1.2 MASSIV dispersion) of MASSIV is responsible for the high level of turbu- z = 3.0 galaxies. Blue points lence in the gaseous discs. In this frame- indicate rotating discs work, results from the MASSIV survey whereas red squares suggest that at z ~ 1.2 cold gas accretion are for non-rotating galaxies. Examples of is less efficient than at higher redshift. SINFONI velocity fields 1011 for these two kinematic classes are shown in A surprising distribution of metals insets. The relation )

ी obtained with MASSIV M (

at z ~ 1.2 (highlighted Unveiling the chemical enrichment of •

M blue line) is compared galaxies at various epochs is a key issue with those derived at to constrain their star formation history z ~ 1 (black line; Kassin et al., 2007) and z ~ 3 and their interplay with the surrounding 1010 (magenta line; Gnerucci intergalactic medium. In particular, the et al., 2011). way metals are distributed inside galaxies gives valuable information about the gas exchange processes (accretion and ejec- tion) between galaxies and their close environment. Until recently, only global measurements of galaxy metallicity were 10 9 50 100 500 available in the high-z Universe. The high –1 S0.5 (kms ) sensitivity of SINFONI enabled resolved metallicity distributions in high-z galaxies galaxies are in fact ongoing mergers or acting systems. However, the exact nature to be achieved and was one of the major merger remnants. A dedicated analysis of of these non-rotating objects (spheroids, objectives of our survey. the merger rate from the observed pairs face-on discs, or merger remnants) is still at z ~ 1–2 is underway and makes use of unclear. Higher spatial resolution imaging This goal has been achieved so far for the entire MASSIV sample (López-Sanjuan and integral field spectroscopy is clearly 26 MASSIV galaxies, where we have et al., in prep.). needed to solve this issue. measured the flux ratio between [N ii] 6584 Å, and Hα emission lines (used as Rotating discs represent ~ 50 % of the The evolution with cosmic time of funda- a proxy for metallicity) in concentric re MASSIV first epoch sample (Epinat et al., mental scaling relations, connecting for gions (Queyrel et al., 2012). These regions 2012). These galaxies are on average example mass and dynamics of galaxies are centred on the Hα peak emission in more massive, more star-forming and (the well-known Tully–Fisher relation), each galaxy, which most often corre- larger than non-rotating ones (Vergani et is still a matter of debate and controversy. sponds to the kinematical centre of the al., 2012), but with similar velocity disper- The discordant results obtained so far galaxy. The sizes of the annular regions sion (~ 60 km/s). An evolution in the frac- might be due to differences in sample were adjusted so as to have enough sig- tion of rotating discs is clearly seen over selection and/or observing limitations, nal for a reliable measurement of the the last 10 Gyr of the Universe. The frac- but there is another quantity which could faint [N ii] 6584 Å line. This allowed us to tion of rotating systems indeed increases play a significant role: the gas turbulence. quantify the radial profile of the [N ii]/Hα continuously from z ~ 3 (~ 35 %, Gnerucci line ratio and hence to derive the metal- et al., 2011) to z ~ 0.6 (~ 65 %; Puech et Indeed, the median value of velocity dis- licity from the inner to the outer parts of al., 2008), supporting the scenario in persion measured in MASSIV galaxies each galaxy. The metallicity gradients which gas in star-forming systems is sta- (~ 60 km/s) marks a transition between of the 26 MASSIV galaxies are shown in bilising into discs as the Universe evolves. turbulent discs (~ 80–100 km/s) seen Figure 5. at higher redshift (z ~ 2–3) and more It appears clearly that the non-rotating “stable” discs (~ 20–40 km/s) observed in The most surprising result is the discov- systems (~ 30 % of the MASSIV sample; the nearby Universe. This transition of ery of seven galaxies with a positive Epinat et al., 2012) are galaxies with a the gaseous velocity dispersion is partly metallicity gradient (Queyrel et al., 2012), low observed velocity shear (< 50 km/s) responsible for the increase of the rota- where the metal content increases from or galaxies for which the kinematics indi- tional support when galaxies evolve. the centre to the outer parts of the gal- cate some ongoing interactions. Such Taking into account the ordered (rotation) axy. This result is surprising because this a population of galaxies has already been and chaotic (dispersion) motions, there behaviour is rarely observed in nearby observed at higher redshift both in the is a clear relation between stellar mass galaxies. A close inspection of these gal- SINS and LSD/AMAZE samples. These and dynamics of MASSIV galaxies (see axies reveals that the majority of them objects are smaller on average than rota- Figure 4), a relation which evolved signifi- (5/7) are interacting or merging systems. tors and are often associated with inter- cantly between z ~ 3 and z ~ 1 (Vergani This indicates that interactions might be

The Messenger 147 – March 2012 35 Astronomical Science Contini T. et al., Teenage Galaxies

Figure 5. Metallicity gradients for 26 MASSIV galaxies. The yellow/blue/ green regions represent the 1σ errors associated to the gradients (red lines). Blue (green) labels indicate the galax- 1NS(RN -1NS(MS 1NS(RN -1NS(RN -1NS(MS ies for which the gradient is positive (negative) with a high confidence level. For each galaxy the dynamical (Rot = rotating disc, NRot = no rotation) and environment (Iso = isolated, Int = interacting) classes are indicated. -1NS(RN -1NS(RN -1NS(MS 1NS(MS -1NS(RN ' 1NS(RN 1NS(RN 1NS(RN 1NS(RN -1NS(RN NF . K 1NS(RN 1NS(RN 1NS(RN 1NS(MS -1NS(MS 1NS(MS -1NS(MS -1NS(RN 1NS(RN 1NS(RN -1NS(RN Q@CHTRJOB the main mechanism responsible for a merging as cosmic time evolves, with a ter/submillimeter Array (ALMA) will be the significant infall of metal-poor gas onto transition epoch around z ~ 1–1.5. obvious step towards a full description of the galaxy centre. the galaxy growth in the young Universe.

The other mechanism put forward to Next steps explain the high occurrence of positive References metallicity gradients in z ~ 3 isolated The SINFONI observations are now Bouché, N. et al. 2010, ApJ, 718, 1001 discs is cold accretion (Cresci et al., completed. The full exploitation of the Contini, T. et al. 2012, A&A, 539, A91 2010). However this occurrence drops unique MASSIV dataset is underway, Cresci, G. et al. 2010, Nature, 467, 811 to about 15−20 % at z ~ 1.2 (Queyrel looking forward to further new and excit- Epinat, B. et al. 2012, A&A, 539, A92 et al., 2012) and is almost equal to zero ing discoveries. In the short term, dou- Förster Schreiber, N. M. et al. 2009, ApJ, 706, 1364 Förster Schreiber, N. M. et al. 2011, The Messenger, in the local Universe. If cold accretion bling the statistics in the highest redshift 145, 39 is the main process able to explain the range (z > 1.2) will allow us to better Gnerucci, A. et al. 2011, A&A, 528, 88 positive metallicity gradient in high-z probe the dominant mechanisms at play Kassin, S. A. et al. 2007, ApJ, 660, 35 isolated discs, this mechanism does not in the overall process of galaxy assem- Law, D. R. et al. 2007, ApJ, 669, 929 Le Fèvre, O. et al. 2005, A&A, 439, 845 dominate the galaxy assembly at lower bly. New observations of MASSIV galax- Maoilino, R. et al. 2010, The Messenger, 142, 36 redshifts (z < 2). ies at the VLT with X-shooter and SINFONI Puech, M. et al. 2008, A&A, 484, 173 are already planned to address specific Queyrel, J. et al. 2012, A&A, 539, A93 To conclude, all the results obtained so questions, such as the ubiquity of posi- Vergani, D. et al. 2012, A&A, in press, arXiv:1202.3107 far from the MASSIV survey favour a tive metallicity gradients and the level of scenario in which the mass assembly of gas turbulence in high-z discs. In the star-forming galaxies is progressively longer term, taking the census of the cold Links shifting from a predominance of smooth gas content and dynamics in MASSIV 1 MASSIV database: cold gas accretion to a predominance of galaxies with the Atacama Large Millime- http://cosmosdb.lambrate.inaf.it/VVDS-SINFONI/

36 The Messenger 147 – March 2012 See West and Emsellem, p. 44. p. Emsellem, and West See mates rather than melts at ALMA’s high altitude. called formations snow and ice unusual the explore to opportunity the had students and Fellows Days, Fellows ESO the during avisit of part As Lower: Release eso1149 for more details. See left). from (first Sterzik Michael and left) from (third Tarenghi Massimo representatives ESO and delegation Belgian the of members by nied accompa 2011 shown is and 5December Monday (standing third from right) visited Paranal on Belgium of Prince Crown Philippe, Prince Upper: penitentes , which form because snow subli snow because form , which - - Astronomical News Astronomical News

Report on the Workshop Ten Years of VLTI: From First Fringes to Core Science

held at ESO Headquarters, Garching, Germany, 24–27 October 2011

Leonard Burtscher1 Françoise Delplancke2 Roberto Gilmozzi2 Jorge Melnick2

1 Max-Planck-Institut für extrater- restrische Physik, Garching, Germany 2 ESO

The tenth anniversary of first fringes with the VLT interferometer (VLTI) was celebrated by a workshop to trace the history and progress of VLTI, review the science achievements and present the next generation instruments. High- lights of the meeting are reported and the panel discussions summarised.

To celebrate the tenth anniversary of the first fringes at the Very Large Telescope Interferometer, more than 100 astronomers from diverse scientific backgrounds came together at ESO’s Headquarters. The four-day meeting featured 54 talks, of which ten were invited reviews; there were also 26 poster presentations and two panel discussions. The presentations are available for download from the Figure 1. The conference photo in the entrance hall A number of talks reported on several conference web page1. of ESO Headquarters. recent attempts to reconstruct images of protoplanetary discs using VLTI data. The stage was set by an account of how Furthermore, the dust composition of the the VLTI came into being, from the first The field of star and planet formation was discs was examined and a crystallinity suggestion by Antoine Labeyrie to the introduced by three review talks. During gradient found, in the sense that there is political birth of the VLTI in the late 1970s, the formation of stars, an accretion disc a larger crystallinity in the inner parts of to ESO Council approval in 1987 and of gas and dust forms through which the disc, as expected from thermal re- the financial and technical challenges that material is transported close to the young processing of dust grains in the vicinity of had to be surmounted after the approval. star. This “protoplanetary disc” is also the sublimation radius. Towards the end A good place to read up on the genesis thought to be the place of planet forma- of the session, the first results from an of the VLT and VLTI is Woltjer (2006). tion, as it provides the dust particles interferometric survey of T Tauri stars that that are built up into ever larger grains is currently being conducted with the and agglomerations until eventually a VLTI visitor instrument PIONIER (see Zins Science sessions planet emerges. Despite its importance et al., 2011) were presented. For the stars in star and planet formation, the detailed studied so far, the total flux was lower The scientific programme consisted of structure of the innermost regions of than expected from an extrapolation of three days of talks and half a day of these discs (the terrestrial-planet-forming the visibility model, indicating contribu- plenary discussions. The scientific talks region) was unknown before the advent tions from larger scales (possibly through were divided into sessions reflecting the of infrared interferometry, due to the lack scattering) around these stars. diversity of the research areas in which of resolution of single-dish telescopes. optical interferometric observations play a Studies with the VLTI and other interfer- In the field of stellar astrophysics, the role: star and planet formation, stellar ometers have resolved the inner rims of review talks emphasised that the mass– astrophysics, evolved stars, asteroids and these discs and confirmed that they lie radius relation is essential for stellar active galactic nuclei (AGN). Here we sum- close to the dust sublimation radius. They models and pointed out how observa- marise a number of results that underline have also probed the geometry of the tions with optical interferometers con- the impact of optical interferometry, and disc and found that these discs have a strain such models by directly measuring especially of the VLTI, on these areas. “puffed up” inner rim and that the rim is the radii of stars. Recent observations curved, as theoretically expected. actually found the radii to be slightly

38 The Messenger 147 – March 2012 example, by following the time evolution Next generation instrumentation of the outburst of the recurrent nova T Pyxis earlier in 2011 with both the VLTI The science talks were followed by a and the CHARA Array, it was shown that session presenting the next generation simple spherical models for the outflow- instruments of the VLTI. A report on the ing material are incorrect, and that the first science results from PIONIER dem- morphology is best described as a bipo- onstrated how efficient interferometric lar flow — this was later confirmed by observations are, once four telescopes NACO observations. are combined at the same time. The latest results of the astrometric com The asteroid observations with the VLTI missioning of the PRIMA instrument (see finally convinced us that interferometry van Belle et al., 2008) were presented. might contribute to saving the planet! With MIDI observations it is possible to The near-infrared second generation VLTI measure the size, shape and thermal instrument GRAVITY was presented, inertia of the main belt asteroids — quan- with particular emphasis on the techno- tities that are otherwise hard to quantify. logical challenges (see Eisenhauer et al., The thermal inertia determines the 2011). In order to achieve the necessary strength of the Yarkovsky effect that can resolution to observe orbits and flare modify the orbits of the asteroids so events at less than six Schwarzschild that they may become potentially danger- radii from the supermassive black hole in ous near-Earth objects. the Galactic Centre — this corresponds to an angle of 10 microarcseconds — Figure 2. Conference poster depicting the VLTI For the area of AGN research, the review the GRAVITY team will improve the infra- among the future facilities in the next decade — talks concentrated on the progress structure of the VLTI (including infrared ALMA, E-ELT and the James Webb Space Tele- scope (JWST) — and a selection of images of a brought about by current interferometers adaptive optics for all telescopes, the variety of circumstellar discs. and outlined the expectations for future metrology system from the instrument to interferometers. Apart from confirming the VLT primary mirror, and a sophisti- the unified model of AGN, which invokes cated fringe tracker using a Kalman con- larger than predicted by models — a a dusty “torus” to explain the two dif troller) as well as provide a very sensitive result which modellers will have to ferent spectral types, observations with instrument by harvesting as many pho- address. Talks on the cosmological dis- the VLTI also showed that the tori of tons as possible. tance scale highlighted the importance edge-on (type 2) objects differ from gal- of well-understood errors in Cepheid axy to galaxy, both in geometry and in The thermal infrared second generation distance measurements to calibrate the temperature structure. On the other hand, VLTI instrument MATISSE was also first rung of the cosmic distance ladder. face-on (type 1) objects seem to show a presented. Compared to the current mid- A programme to reach beyond the uniform radial brightness distribution, as infrared instrument, MIDI (Leinert et al., current uncertainty of the present-day shown in a mini-survey using both near- 2003), MATISSE will widen the spectral

Hubble parameter H0 (3 %) by studying infrared observation at the Keck Interfer- coverage to include the L-band, which Galactic Cepheid stars with the inter ometer and MIDI at the VLTI. A debate contains several interesting spectral fea- ferometric Baade–Wesselink method was is still open as to whether or not the sizes tures of water ice and polycyclic aromatic presented. In this method the diameter of the tori scale uniformly with AGN lumi- hydrocarbons (PAHs). Like GRAVITY, and pulsation velocity of the stars are nosity (i.e., are independent of spectro- it will also combine the light of four tele- measured interferometrically and spec- scopic type) and whether or not this rela- scopes, providing six baselines and three troscopically to achieve a distance tion holds also for high luminosities. The independent closure phases at a time measurement independent of the period– first VLTI Large Programme is address- and thereby allow the reconstruction of luminosity relation. Using the FLUOR ing that question. The first AMBER obser- real images for the first time in theL - and instrument at the US-based Center for vations of an AGN in “no track mode” N-bands at angular resolutions of about High Angular Resolution Astronomy using the AMBER instrument (see Malbet 3–10 milliarcseconds. (CHARA) interferometer, it was found that et al., 2007) were also presented. In order the assumptions about the pulsation of to spectro-interferometrically resolve an the stars break down when a precision of emission line in the broad line region Synergies better than 1.5 % is reached. In order to using the differential phase signal, a fac- increase the precision, more refined stel- tor of about five in sensitivity improve- The two largest ESO projects of the dec- lar models are therefore needed. ment is still needed. ade, the Atacama Large Millimeter/submillimeter Array (ALMA) and the European For the evolved stars, the review talk Extremely Large Telescope (E-ELT), were stressed the many aspects in which inter- presented, and in particular how they ferometric observations contribute. For are expected to work together with the

The Messenger 147 – March 2012 39 Astronomical News Burtscher L. et al., Report on the Workshop “Ten years of VLTI”

VLTI. Crucially, ALMA is offered as a high- The panel moderator gave an overview of the visual waveband would also be inter- fidelity imager — and not as an inter recent developments that appear interesting for AGN, more sensitivity and ferometer — to open it up to the whole esting for the future of the VLTI. One of reliability for observations of weak targets science community and not only to those the most promising developments is the are of greater interest to AGN interfero- who are interferometrically inclined. At “hybrid mode”, i.e. the combination of metrists. Hybrid UT–AT combinations the end of the session views were pre- one (or more) of the large Unit Telescopes would add new baselines to the array and sented on the high-resolution astronomy (UTs) with one (or more) of the smaller thereby improve image fidelity and they infrastructure a few years into the future. Auxiliary Telecopes (ATs). This mode was would also increase the sensitivity com- In contrast to ALMA’s approach, the audi- first demonstrated in 2011 and will offer pared to AT-only baselines. The prevailing ence was asked to change its mental pic- more baselines and better sensitivity outlook at the panel discussion on the ture of optical interferometers: these are (compared to AT-only operations), answer- VLTI as a common user facility was that not high-resolution facilities for all kinds ing two of the biggest wishes of VLTI the ability to reconstruct real images of science, but very specialised obser users. Another important development is will bring a huge step forward and attract vatories that contribute crucially to a few the introduction of the infrared avalanche new users to the VLTI. selected science cases. photodiode detectors that are on the verge of entering astronomy. It is believed that these photon-counting detectors Acknowledgements Panel discussions will change interferometric observation The authors would like to thank Hendrik Linz, Henrik and bring about a breakthrough in terms Beuther and Myriam Benisty for input and comments. On the last day of the workshop there of sensitivity and the way interferometers were two panel discussions: the future of can be operated. the VLTI; and the challenges of (optical) References interferometers as a common user facil- Regarding the further development of Eisenhauer, F. et al. 2011, The Messenger, 143, 16 ity. The former was considered as an the VLTI, several participants suggested Leinert, C. et al. 2003, The Messenger, 112, 13 initial discussion forum to assemble the exploring the possibility of expanding Malbet, F. et al. 2007, The Messenger, 127, 33 thoughts of the community and provide the spectral coverage to the visual. This van Belle, G. et al. 2008, The Messenger, 134, 6 Woltjer, L. 2006, Europe’s Quest for the Universe ideas for the further development of the would require a re-coating of all mirrors (Berlin: Springer) VLTI after the second generation instru- in the VLTI optical path, but since the Zins, G. et al. 2011, The Messenger, 146, 12 ments. This discussion provides invalua- maximum VLTI baseline length is limited ble input to help ESO shape its plans for by the size of the Paranal platform, this Links the future of the VLT/I in the E-ELT era. is the only way to increase the resolution, which is seen as the necessary step 1 Workshop webpage: http://www.eso.org/sci/ forward for stellar interferometry. While meetings/2011/VLTI_2011.html

A photograph from 2009 showing the Very Large Telescope Interferometer (VLTI) laboratory at the Paranal Observatory. In the foreground, under- going maintenance, the differential delay lines of the PRIMA (Phase Referenced Imaging and Micro arcsecond Astrometry) instrument are seen.

40 The Messenger 147 – March 2012 Astronomical News

ESO Telescope Bibliography: New Public Interface

Uta Grothkopf 1 – semi-automated screening of journals – overview of top five journals and ESO Silvia Meakins1 for ESO-defined keywords using FUSE, instruments; a full-text search tool specifically – spell-checker for search terms (“Did designed for this purpose. At present, you mean...?”); 1 ESO the following journals are routinely screened: A&A, A&ARv, AJ, AN, ApJ, Results list: ApJS, ARA&A, EM&P, Icarus, MNRAS, – paper titles linked to detailed display; The ESO Telescope Bibliography (telbib) Nature, NewA, NewAR, PASJ, PASP, – faceted filtering to limit search results; is a database of refereed papers pub- P&SS, Science; – programme IDs linked to data in the lished by the ESO users’ community. All – human inspection of each paper that ESO archive; papers that use, partly or exclusively, contains at least one of the keywords; – various options to sort the results; data from ESO telescopes are included. – identification and cross-checking of all – export feature for further use of results The front end of telbib has undergone instruments and programme IDs used; set; a complete transformation and a state- – querying of the ESO observing of-the-art interface has been imple- schedule and ESO archive to obtain Detailed record display: mented to provide new features and programme IDs not mentioned in the – full list of observing facilities and addi- sophisticated search functionality. telbib paper; tional tags; has been created and will be further – correspondence with authors and – highlighted search terms; developed by the ESO librarians. instrument scientists in case of doubt. – recommendations for other papers of interest. Therefore, telbib is a unique source that Introduction connects published articles with the In the following, we will explain and observing programmes that generated illustrate the main features of the new The ESO library maintains the Telescope the data. The database is used to derive features of telbib access. A full descrip- Bibliography1, a database of refereed publication and citation statistics of tion of telbib, the associated full-text papers that use ESO data. It is compiled specific telescopes and instruments and search system FUSE, and the new telbib by scanning the major astronomy jour- can help to define guidelines for future front end can be found in Meakins & nals for scientific papers that contain any facilities. Grothkopf (2012). of the ESO-defined keywords (e.g., telescope and instrument names). Biblio- A description of the previous web inter- graphic information, citations and some face can be found in Delmotte et al. Search interface further metadata are imported from the (2005). In December 2011, a new public NASA Astrophysics Data System (ADS)2. interface was released, using Apache The new public telbib interface offers a Standardised descriptions of telescopes Solr and PHP. Key features include: wide range of query options for easy and instruments, survey names and access to the information. These include other tags as well as programme IDs are Search interface: searches for bibliographic information assigned by the ESO librarians. – query by bibliographic information or (authors, title words, abstract, publication instrument, telescope and programme year, etc.) as well as for observing facili- Access to the full texts of papers in ID; ties (instruments, telescopes) and pro- telbib is governed by subscription. telbib – autosuggest support for author, bib- gramme IDs. The main search screen records contain links to the ADS from code, and programme ID searches; provides a dedicated area on the lefthand where typically the PDF and HTML versions can be obtained, provided a subscription for these journals is in place. Alternatively, the articles may be available through open access agreements. In many cases ADS also provides links to the freely available manuscripts at the arXiv/astro-ph e-print server.

telbib contains records from 1996 onwards. Programme IDs and instrument tags are available for all papers using Paranal or Chajnantor data as well as for papers based on La Silla data since publication year 2000. We make extensive efforts in order to identify all refereed Figure 1. The telbib papers that use ESO data including: search interface page is shown.

The Messenger 147 – March 2012 41 Astronomical News Grothkopf U., Meakins S., ESO Telescope Bibliography: New Public Interface

Figure 2. An example results page from a telbib Figure 3. Detailed record display of a bibliographic search is shown. item using ESO data. side where the top five journals and in Search results can be limited by using the as citations at ADS. Links to some struments are listed, indicating the num- faceted filtering in the “Refine Search” papers of similar content to the one cur- ber of records in telbib for each journal area. Facets are available for publication rently shown are available at the bottom and using data from these instruments, years, journals, and instruments. For of the page. This section is entitled “Also respectively. Similarly, the most recent the latter two filters, the top five among of interest?” and invites users to explore five years are displayed together with the these results are shown, together with the the displayed recommendations. number of papers per year (see Figure 1). five most recent years. Clicking on the “more…” button displays the entire lists. Certain search fields provide a spell- Results sets can be exported into Future enhancements checker. For instance, if author names comma-separated (.csv) or tab-separated or title words entered in the respective (.txt) format for further use. A search interface, even one that has fields do not lead to any hits, the system just been released, is always a work in will respond instead with the question progress. Consequently, we are already “Did you mean…?”, followed by sugges- Detailed record display focusing on the next round of improve- tions that will turn up results. In addition, ments. after only two characters have been The detailed record view (Figure 3) shows entered in the authors, bibcode, or pro- all ESO observing facilities that were As statistics are of increasing interest, gramme ID fields, an autosuggest fea- used in the paper, as well as additional we are currently investigating the option ture will start, offering search terms which tags, indicating, for instance, use of of a dedicated statistics area which exist in the index. archival data. Search terms are displayed will be accessible from the public search in italics so that they can be easily iden interface. At present, basic statistics tified. Instruments, telescopes, and derived from the Telescope Bibliography Results page observing sites provide hyperlinks that are available through a document located initiate new searches to retrieve other on the Libraries homepage3. More spe- Papers that fulfill the query parameters papers that use the same facilities. cific reports can be provided by the ESO are displayed on the results page in librarians. Soon, users of the public inter- six columns, showing the publication For programme IDs, two links are offered. face will be able to create and visualise year, first author, title, instruments, pro- Clicking on the programme ID itself statistics based on user-defined criteria, gramme ID and the bibcode of each will evoke a new search for all papers that for instance comparisons of specific paper (see Figure 2). Titles are linked to used data from the same programme. instruments over a range of publication the detailed view of records. Programme Selecting “access to data” takes users to years. IDs lead to the ESO observing schedule the observing schedule and from there and from there to the archive where the to the archive where the respective data Feedback on the new telbib interface is data can be requested for further use. can be requested if the proprietary period very welcome. For questions or sugges- Bibcodes are connected to the abstracts has ended. tions, please contact us at library@eso. at ADS from where the full-text versions org. A more detailed description of the of articles can be accessed. Citations are loaded on-the-fly from ADS, telbib database is available on the web4. hence they are as current and complete telbib users who would like to stay

42 The Messenger 147 – March 2012 Astronomical News

informed about newly added papers are and Myha Vuong from ESO, for their excellent Links invited to subscribe to our RSS feed 5. help and support of the previous telbib front end. FUSE and telbib make extensive use of NASA’s 1 ESO Telescope Bibliography: http://telbib.eso.org/ Astrophysics Data System. 2 Astrophysics Data System (ADS): http://adsabs.harvard.edu Acknowledgements 3 Some telbib statistics: http://www.eso.org/libraries/ References edocs/ESO/ESOstats.pdf We are very grateful to Chris Erdmann, now at the 4 On-line help for telbib: Harvard–Smithsonian Center for Astrophysics, Delmotte, N. et al. 2005, The Messenger, 119, 50 http://telbib.eso.org/help.html Cambridge, MA, USA who created the first versions Meakins, S. & Grothkopf, U. 2012, ADASS XXI, 5 ESO libraries RSS feed: of FUSE and telbib, as well as Nausicaa Delmotte Astronomical Society of the Pacific (ASP), in print http://www.eso.org/sci/libraries/rss.php

Greetings from the ESO Council

Xavier Barcons1 Figure 1. Xavier Barcons pictured in the Council Room at ESO Head- quarters. 1 Instituto de Física de Cantabria (CSIC-UC), Santander, Spain

I am a research professor on the Spanish Council for Scientific Research (CSIC) and was recently elected President of ESO Council, a very high honour and a great challenge for me. I am originally Catalonian, and have been based in Cantabria (in the north of Spain) for most of the last 30 years. My astronomical research is conducted mostly at X-ray wavelengths. Active galactic nuclei, as the signposts of growing supermassive black holes, are my pet objects. I am deeply involved in ESA’s X-ray observatory Athena candidate mission, now com peting for a launch slot in 2022, and am chair of its science working group. My research activity has slowed down during the last decade as I have been advising cover a part of Spain’s special contribu- At ESO every year is exciting, but maybe the Spanish Government on astronomy tion to ESO. Spain joined ESO with effect not all are equally exciting. In particular matters. On a more personal level, I enjoy July 2006 (Barcons, 2007) and I was 2012 is bound to be an incredibly exciting sharing experiences with my family (wife appointed first observer and later govern- year for at least three reasons. The first is Mar, son David and daughter Sara) and ment representative on the ESO Council. that we will see the first scientific results long-range mountain biking (e.g., along At ESO I have served in the Observing from ALMA, now that Early Science the Saint James’s Way). And yes, I also Programmes Committee, Scientific Strat- observations are underway. It has been love watching FC Barcelona play delight- egy Working Group, New Member States very reassuring to see how astronomers ful football. Working Group, the Atacama Large in the ESO Member States have mas- Millimeter/submillimeter Array (ALMA) sively requested science observations in I started to travel frequently to ESO Board, the ALMA Budget Committee and this first phase of ALMA operations and Garching in 2004 when I was asked to the ALMA Personnel Committee. this will lead no doubt to substantial sci- negotiate the in-kind deliverables to entific progress.

The Messenger 147 – March 2012 43 Astronomical News

Secondly, it is expected that during Finally, this is a very special year since cooperation, a lively community, an 2012 the construction of the European ESO is celebrating its 50th anniversary. I enthusiastic staff and a careful balance Extremely Large Telescope (EELT), “the recommend reading the preamble of between operations of world-class facili- world’s biggest eye on the sky”, can the ESO Convention in order to appreci- ties and construction of new ones for the be submitted to ESO Council for ate the enormous progress achieved benefit of ESO Member States. approval. The Member State delegations in the five decades of ESO’s existence. are working hard to obtain the funding We should take this opportunity to convey and approval from their governments to the governments and the full popu References for this challenging but captivating pro- lation of our Member States our pride in Barcons, X. 2007, The Messenger, 127, 2 ject. We are all glad to see that, even in being able to build the most powerful the current difficult economic circum- and productive ground-based astro stances, a number of Member States are nomical observatories in the world. This already prepared to commit funding. achievement is the result of sustained

Report on the ESO Fellows Days in Chile 2011

held at the ESO Offices in Santiago, Chile, 21–25 November 2011

Michael West1 The ESO Fellows Days were held in of welcome to the Fellows, reminding Eric Emsellem1 Chile from 21–25 November 2011 and them of the importance that ESO places brought together more than 30 ESO on its Fellowship programme and its Fellows from Garching and Chile, as well value in the development of their careers. 1 ESO as the two Heads of the Offices for Sci- ence. The purpose of these gatherings is The first three days of the meeting were to learn more about the exciting research devoted to short presentations about The 2011 ESO Fellows Days were held being done by the impressive group each Fellow’s current research activities. in Chile and brought together over of ESO Fellows in Vitacura and Garching ESO Chile astronomers and students in 30 ESO Fellows from Garching and and hopefully to stimulate new scientific Vitacura also attended many of the talks. Chile. As well as presentations of re collaborations. search and social activities, the Fellows Figure 1. Social activities on the Fellows Days Days included a visit to San Pedro de ESO Director General Tim de Zeeuw included lunch and a tour of the Casa del Bosque Atacama and the ALMA site. kicked off the meeting with warm words winery near Santiago.

44 The Messenger 147 – March 2012 Astronomical News

A special lunchtime talk by Massimo Tarenghi provided an interesting historical and personal overview of the development of the La Silla and Paranal observatories. The programme also included career-training workshops led by the Heads of the Offices for Science on the topics of “Fine-tuning Your Job Appli cations” and “How to Give a Good Job Interview”, with the goal of enhancing the marketability of ESO Fellows and students. A lunch and tour at one of Chile’s many wonderful wineries provided a nice opportunity for Fellows to get to know each other better and to gain a deeper appreciation of Chilean culture (see Fig- ure 1).

A highlight of the Fellows Days was a visit to the Atacama Large Millimeter/submillimeter Array (ALMA) on Chajnantor (Figure 2), including an overnight stay in San Pedro de Atacama. Everyone was Many thanks are due to all the ALMA Figure 2. More than 30 ESO Fellows and students excited to see ALMA operations in action staff who made this visit possible, and visited the ALMA site on Chajnantor, accompanied by the Heads of the Offices for Science in Garching at the Operations Support Facility (OSF) especially to Paulina Jiron of ESO for and Chile. and the ALMA Operations Site (AOS), and all her hard work organising the travel ESO ALMA COFUND Fellow Anaëlle and accommodation. We were greatly Maury gave a very informative tour of the impressed by the efficiency and profes- prized souvenirs for the Fellows and stu- ALMA facilities. During the visit the sionalism of everyone at ALMA. It’s not dents as a nice reminder of their exciting Fellows had an opportunity to discover easy to handle visits by a group of this visit! the unusual local ice and snow forma- size to an altitude of 5000 metres, but tions (see the Figure on the Astronomical ALMA managed it perfectly. ALMA hats The next ESO Fellows Days will take News section page, p. 37). to block the fierce sun quickly became place in Garching during 2013.

Call for Nominations for the European Extremely Large Telescope Project Science Team

The European Southern Observatory Specific tasks of the Project Science operations and other scientific aspects invites the astronomical community to Team include responding to specific of the project; nominate candidates for the European requests from the Programme Scientist – Develop the instrumentation plan for Extremely Large Telescope (E-ELT) and providing input and advice to ESO the E-ELT and set the scientific pri Project Science Team. and the E-ELT programme to help: orities for the instrument procurement; – Refine as necessary the -E ELT science – Develop a science perspective on The E-ELT Project Science Team is goals; any major cost/schedule/science trades an advisory working group that will sup- – Refine, as necessary, the Observatory brought forward by the project. port the E-ELT programme during the Top Level Requirements, including construction phase. The E-ELT Project the science requirements and perfor- In addition the Project Science Team is Science Team is not an ESO oversight mance metrics and objectives for the expected to: committee. telescope, the instrumentation, the – Participate in the E-ELT reviews in order to coordinate scientific requirements

The Messenger 147 – March 2012 45 Astronomical News

and assist the E-ELT project in deci- technical expertise. Candidates should Nominations should be justified by a sions as they relate to scientific objec- be ready to dedicate more than 10% of maximum of one page of text, summaris- tives and the scientific performance of their time to the project during the three- ing the relevant expertise (and plans) the programme; year appointment. Funding is available of the candidate for the E-ELT project, – Participate in the refinement of the for extended visits (several distributed or and should be submitted electronically to project science plans and the philoso- continuous weeks) to the ESO Headquar- Samantha Milligan ([email protected]) phy for defining and conducting the ters in the frame of this work. before 31 March 2012. Both self-nomina- science programme; tions as well as nominations by support- – Disseminate this information actively The closing date for sending nominations ers (individuals or groups) are welcome. and explain the goals of the E-ELT to is 31 March 2012. The E-ELT programme the ESO community. will start by contacting candidates there- The terms of reference for the Project after, with the goals of completing a team Science Team can be found at http:// ESO is seeking a representative group of a dozen multi-disciplinary scientists by www.eso.org/sci/facilities/eelt/science/pst of scientists, covering scientific as well as 30 April 2012.

ESO Celebrates its 50th Anniversary

The year 2012 marks 50 years since the ESO Convention was signed by representatives from five European countries — Belgium, France, Germany, the Netherlands and Sweden on 5 October 1962. The anniversary year is an opportunity to look back at ESO’s history, celebrate its scientific and technological achievements and look forward to the future.

A number of events and public initiatives are planned for 2012, as announced on the 50th anniversary web page1, including: – A scientific symposium (see announcement on p. 47); – Coordinated public events in the 15 Member States on the day of the anniversary, 5 October 2012; – A gala anniversary event to take place in Munich on 11 October 2012; – An anniversary exhibition on display at selected locations in the ESO Member States; – A documentary film released on the anniversary day, together with an illustrated book; – Release of the second part of the offi- Links – The first Picture of the Week2 of every cial history of ESO, written by Claus 1 ESO’s 50th anniversary web page: http://www.eso. month in 2012 will be a special Then Madsen, to follow the book by Adriaan org/public/outreach/50years.html.html and Now feature, presenting ESO sites Blaauw, ESO’s Early History (1991). An 2 Picture of the Week: http://www.eso.org/public/ as they looked in the past and as they illustrated timeline of the five decades of images/potw/ 3 look today; ESO is also available3. ESO Timeline: http://www.eso.org/public/about-eso/ timeline.html

46 The Messenger 147 – March 2012 Astronomical News

Announcement of the Conference ESO@50 – The First 50 Years of ESO

3–7 September 2012, ESO Headquarters, Garching, Germany

A special science workshop will be held results, and an outlook for science with Isobel Hook (United Kingdom); Konrad at ESO Headquarters to mark the 50th the E-ELT. Kuijken (the Netherlands); Bruno anniversary. The ESO@50 workshop is Leibundgut (ESO); Maria-Teresa Ruiz intended to provide an original perspec- The meeting will consist of invited reviews (Chile); Monica Tosi (Italy); Linda Tacconi tive on the scientific challenges of the and contributed talks covering the many (Germany); Michael West (ESO). coming decade, building on the achieve- diverse scientific areas in which ESO has ments from the science community contributed, including the Solar System, The Local Organising Committee is using ESO facilities. This five-day work- exoplanets, stellar birth and the interstel- composed of Eric Emsellem, Bruno shop will focus on the main scientific lar medium, stellar death, the Milky Way, Leibundgut, Jorge Melnick, Markus topics where ESO has made important nearby galaxies, galaxy surveys, distant Kissler-Patig, Christina Stoffer, Leonardo contributions. Key speakers will be invited galaxies, galaxy clusters and cosmology. Testi, Svea Teupke and Michael West. to give overviews of each field (including some historical perspective) and then The distinguished Scientific Organising The registration deadline is 31 May 2012. focusing on the present science status Committee is composed of: Beatriz surrounding these questions. The next Barbuy (Brazil); Xavier Barcons (Spain; Further details are available at: science steps will also be emphasised. president of ESO Council); Willy Benz http://www.eso.org/sci/meetings/2012/ Some “bonus” tracks will be included, (Switzerland); Jacqueline Bergeron ESOat50.html or by email to: such as introducing the first ALMA results, (France); Emanuele Daddi (France); Tim [email protected] the latest unpublished VLT/I and La Silla de Zeeuw (ESO); Eric Emsellem (ESO);

Announcement of the ESO Workshop Ecology of Blue Straggler Stars

5–9 November 2012, ESO Vitacura, Santiago, Chile

An accumulation of observational evi- as of the dynamics of clusters. Spread dence now points to the fact that the two over a week and held at the ESO-Chile mechanisms thought to be responsible headquarters in Santiago, the workshop for blue stragglers – mergers and mass will consist of extended invited reviews, transfer – are operating in the same with ample time for contributed talks and cluster: the exact preponderance of one space for posters. mechanism over the other possibly depending on the cluster’s property, that The scientific organising committee is is, the blue stragglers’ ecology. For exam- composed of: Giovanni Carraro (ESO, ple, it would seem natural that the most co-chair); Henri Boffin (ESO, co-chair); populous systems, i.e. globular clusters, Giacomo Beccari (ESO); Alison Sills should produce the largest population (McMaster University, Canada); Melvyn of blue stragglers, irrespective of the Davies (Lund University, Sweden); The existence of blue straggler stars, mechanism involved. Recently, however, Francesco Ferraro (University of Bologna, which appear younger, hotter, and more it was shown that Galactic open clusters Italy); Robert Mathieu (University of massive than their siblings, is at odds seem to contain the largest proportions Wisconsin, USA); Hagai Perets (Harvard with a simple picture of stellar evolution, of blue stragglers, a proportion only University, USA); and Javier Ahumada as such stars should have exhausted approached by the low luminosity dSphs. (Universidad de Córdoba, Argentina). their nuclear fuel and evolved long ago to become cooling white dwarfs. Obser This is the first workshop ever devoted The registration deadline is 31 July 2012. vations have revealed that blue stragglers to these unique objects. The workshop exist in globular clusters, open clusters, aims at bringing together theoreticians Further details are available at: dwarf spheroidal galaxies (dSph) of the and observers in order to compose a http://www.eso.org/sci/meetings/2012/ Local Group and OB associations. Field complete picture of the progress in the bss2012.html, or by e-mail to: blue stragglers have also been identi- field. It will also bring together specialists [email protected] fied from their anomalous kinematics and of binaries and multiple systems, stellar metallicity. evolution and stellar populations, as well

The Messenger 147 – March 2012 47 Astronomical News

Announcement of the ESO Workshop Science from the Next Generation Imaging and Spectroscopic Surveys

15–18 October 2012, ESO Headquarters, Garching, Germany

With the addition of the VISTA and VST imaging survey facilities to the La Silla- Paranal Observatory and the start of the

selected spectroscopic public surveys, ESO/G. Lombardi G. Hüdepohl/ESO G. European astronomy has firmly entered the era of large public surveys. The aim of the workshop is to present scientific results from the first two years of science operations of the VISTA public surveys, the first year of the VST public surveys, and an overview of spectroscopic public survey projects at ESO. The first results from the nine ongoing imaging public surveys from VISTA and VST will be featured through invited talks by the survey PIs, as well as contributed talks from survey team members. The scientific usage of public survey data products, including the fulfillment of the science goals of Figure 1. The two ESO survey telescopes: left, the The main science topics include: the community based on public survey Visible and Infrared Survey Telescope for Astronomy – VISTA public survey science; (VISTA) and, right, the VLT Survey Telescope (VST). archive data, will be discussed. – First results from the VST public survey observations; Another goal of the workshop is to put using public survey data. To this end, con- – Overview of spectroscopic public sur- the ESO public survey projects in the tributed talks from scientists who have veys at ESO; context of other ongoing or planned large used public survey data for their own sci- – Ongoing and planned large survey pro- optical and near-infrared (NIR) imaging ence, but do not necessarily belong jects; surveys, such as SDSS III projects, to any of the specific groups that have led – Synergies between ground-based and PANNStaRRs, LSST, SkyMapper, UKIDSS or executed the surveys, will be encour- space-based surveys; and Gaia, and within the context of spec- aged. The topic of data mining and the – Data mining and the availability of sur- troscopic surveys carried out at other availability of data products for wide sci- vey products for wide science use by telescope facilities and/or as follow-up of ence use by the community will also be the community. imaging surveys. discussed. Contributions from open time and guaranteed time observing (GTO) The deadline for registration and abstract As ESO public surveys cover such a wide projects on the ESO survey telescopes submission deadline is 2 July 2012. range of topics in observational astron- VISTA and VST will also be welcome. The omy, this workshop will not concentrate workshop will include a panel discussion Further details are available at: on specific scientific areas, but rather with a forward look on how large col http://www.eso.org/sci/meetings/2012/ show the exciting new results coming laborations and big projects are organ- surveys2012.html or by email to: from large surveys and how overall astro- ised in other communities. [email protected] nomical knowledge can be advanced

Announcement of the ALMA Community Days: Early Science in Cycle 1

25–26/27 June 2012, ESO Headquarters, Garching, Germany

ALMA, the Atacama Large Millimeter/ while construction and commissioning by the central European ARC hosted at submillimeter Array, a global collaboration activities continue. The interface between ESO Headquarters in Garching, Germany. involving Europe, North America, East ALMA and its potential users is provided Asia and the host country Chile, is cur- by the local ARC (ALMA Regional Cen- ALMA Early Science Operations started rently carrying out first scientific observa- tre). In Europe, the ARC consists of a net- with Cycle 0 in September 2011. tions for the astronomical community, work of regional ARC nodes coordinated Nearly 1000 proposals were received from

48 The Messenger 147 – March 2012 Astronomical News

) Figure 1. Panoramic view of the Chajnantor plateau by night, showing many antennas of the Atacama Large Millimeter/submillimeter Array (ALMA). twanight.org

ture a series of technical and scientific

ESO/B. Tafreshi ( presentations related to ALMA, the Euro- pean ARC and capabilities in Cycle 1. The remainder of the workshop will be dedicated to hands-on tutorials focusing on the preparation of Cycle 1 observing proposals using the ALMA Observing scientists around the world, around cycle, the fraction of time available for Tool (OT). Depending on their level of one tenth of which were scheduled for Early Science observations is expected expertise, the workshop participants will observation. Although the technical to increase as the array nears comple- be given the choice of attending either capabilities offered in Cycle 0 are limited tion. Additionally, the higher sensitivity a compact one-day tutorial or a more compared to those envisaged for Full and technical capacity of ALMA in Cycle 1 exhaustive two-day session. This should Science Operations, the data obtained has the potential to yield ground-breaking enable novice and advanced ALMA users are already of remarkable accuracy and scientific results largely surpassing those alike to create observing projects making quality. In Cycle 1, an enhanced set of achievable using existing facilities. full use of the unique capabilities of ALMA ALMA technical capabilities and a larger during Cycle 1. array of antennas will be offered to the The aim of the 2012 Community Days astronomical community. While the build- is to prepare the European astronomical Further information can be found at: ing and commissioning of the full array community for Cycle 1 of ALMA Early www.eso.org/sci/meetings/2012/alma_ will continue throughout this observing Science Operations. The first day will fea- es_2012.html

Announcement of the NEON Observing School 2012

10–22 September 2012, Asiago Observatory, Italy

The Network of European Observatories will be conducted under the supervision in the North (NEON: Asiago Observatory of experienced astronomers. The hands- [Italy], Calar Alto Observatory [Germany, on sessions are complemented by lec- Spain], European Southern Observatory, tures on observational techniques. Haute Provence Observatory [France], and La Palma Observatory [ING and The school is open preferentially to PhD NOT: UK, the Netherlands, Spain and the students and postdocs in astrophysics Nordic Countries]) is holding the 10th who are nationals of a Member State NEON Observing Summer School this or an Associate State of the European year at the Asiago Observatory in the Union, but some places will also be Veneto region of northern Italy. available for nationals of surrounding countries. The purpose of the school is to provide an opportunity to gain practical experi- The application deadline is 20 April 2012. ence in observation and data reduction in astrophysics. The observing runs will More details can be found at: take place at the 1.82-metre Cima Ekar http://www.iap.fr/neon/ or by email to: and 1.22-metre Galileo telescopes focus- [email protected] ing on modern astrophysical topics. The observations, data reduction and analysis

The Messenger 147 – March 2012 49 Astronomical News

Fellows at ESO

Mark Westmoquette

I think I was around age 16 or 17 and doing my A-level examinations when I developed a serious interest in astronomy. This was due in part to a particularly engaging teacher called Mr Sheldrake, and, in another part (although I hate to admit it now) to Star Trek. Moving swiftly on ... My interest grew, such that in 1999 I decided to leave home and go to Uni- versity College London (UCL) to study astrophysics. Unbeknownst to me then, I wasn’t to escape UCL for another 11 years. The undergraduate research project that I did with Linda Smith set me up very well to do a PhD with her on super star clusters, feedback and galactic winds. I then did four years as a postdoc at UCL before being awarded an ESO Fellowship and moving here to Mark Westmoquette Munich. nated by advertising and profit, with the ments, and I have made extensive use of After my initial naïve and idealistic period potential of financial ruin always (and instruments such as VIMOS and FLAMES, of enthusiasm, I have encountered a particularly recently) just round the cor- and of course the Hubble Space Tele- number of moments in the past ten years ner, we can still find billions of euros scope. when the thoughts of “what’s the point to fund projects of pure curiosity is mar- of studying astronomy?” and “is it a good vellous! Doesn’t knowing that the Sun Among my extracurricular interests, yoga use of my life?” have risen to crisis point. was born out of an interstellar gas cloud and zen are the two most important. One particularly memorable one came that contained chemicals from many One of the highlights of my week is the just after I’d finished my PhD and was previous generations of stars give more yoga class I run every Tuesday for ESO travelling before starting my postdoc. I meaning to life than knowing that 37 % staff. clearly remember realising that wherever of smartphone users use their devices for I was, from a dark beach in Costa Rica shopping? to a wedding reception in Gloucester- Amelia Bayo shire, people were always fascinated to In my opinion, one of the most important find out that I study astronomy and often things in life is to find a passion and do Unlike most astronomers, studying started asking the same fundamental it 100 %. I feel extremely honoured to be the mysteries of the sky did not even questions about the Universe as I was in the position of being able to do that. Not cross my mind when I was a child. I grew actually being paid to research. Perhaps only am I paid to do it, but in academia up in a “biggish” city in the south of it is because the Universe is so vast, my passion is continually and actively Spain, Malaga, where nobody around me so full of wonders (albeit often very com- nurtured. That is part of what makes ESO was especially fascinated by astronomy. plicated and low signal-to-noise won- such an amazing place to work. I’m sur- From a young age, though, as my parents ders), and the “what’s out there?” ques- rounded on a daily basis by high-flying, can testify, it was clear that I wanted tion is so deeply engrained in our human brilliant people with high aspirations, and to do research. I loved discovering new consciousness. This universal interest have many possibilities to meet and things, and the challenge of tackling convinced me that I was doing something collaborate with other astronomers in a problem until I could find the way to meaningful. ESO, in the Garching campus or visitors unveil what was going on. passing through. I have come to think of studying astron- I studied mathematics at Universidad omy as something similar to being an My current research focuses on deter- de Malaga and I was leaning towards artist or musician. Since it has almost no mining the interstellar medium conditions, topology or geometry. But life decided commercial value — even Google can’t both within the cores of nearby starburst otherwise. I moved to Madrid where the sell a galaxy evolution model — its value galaxies and in their resulting feedback- possibilities to do research were way to society comes solely through curiosity driven winds, with the aim of understand- higher. At the Universidad Complutense (of our origins), like art whose value is ing how these winds are driven and de Madrid there was a programme for based on curiosity of the human condi- evolve. Integral field units (IFUs) are ideal students to participate at the European tion. That, in this capitalist world domi- for studying these complex gas environ- Space Astronomy Center (ESAC, at that

50 The Messenger 147 – March 2012 time the Villafranca satellite tracking sta- tion) in small summer projects. There was no such thing for pure maths students, so I joined the programme and that is how I got “hooked”.

I remember perfectly well the first day I arrived at ESAC. The place was the most advanced technological complex I had ever seen. But this was nothing compared to talking to my supervisor for that little project. ESA staff astronomer, Pedro Garcia Lario, was clearly in love with his research. In less than two minutes he convinced me that one would be out of one’s mind not to want to study planetary nebulae! He showed me beautiful images, and he could name plenty of objects by those weird names... I left the office fully convinced that this was the kind of passion I wanted for my career, and so, “astrophysics it was!”. Amelia Bayo I finished studying mathematics, but with majors in astronomy and then started my eyes get used to the dark. There I During my PhD I realised that complete two Masters, one in artificial intelligence found what I had wanted ever since I samples are mandatory in order to (connected to the Virtual Observatory) went to ESAC for the first time: I fell in reach any strong conclusions. Therefore, and one in astrophysics. With Masters love with the southern sky, and I decided I joined a very ambitious spectroscopic ongoing, it was then time to look for a that Chile and the ESO observatories survey that, using ESO telescopes, PhD project. should become my home very soon. will complement Gaia at the lower end of the mass function. On the other hand, I learned about an opening for a PhD My main research field is the study of to analyse and fully exploit the database position at LAEFF; a Spanish laboratory the formation of brown dwarfs, those that this project will generate, a solid located on the ESAC campus. I went intermediate objects between stars and base in astrostatistics and inference is for the interview with David Barrado y planets. Do they form like the stars? absolutely mandatory. In a sense I am Navascues and the experience proved Do they form like the planets? How often returning to my mathematical background, very different from my first day at ESAC. do they host planetary mass objects? something I enjoy a lot. David did not show me the “in love with Do their discs evolve similarly to the astronomy” side of him, he showed me protosolar disc? To answer these ques- Being at ESO Chile has allowed me to the direct and competitive one and let tions we need to compare their proper- improve my observing skills and to me know very clearly that I was the one ties with those of low-mass stars. During deeply understand some of the instru- asking for a job and that I had to be my PhD I studied an extremely interesting ments that I use for my science. Besides able to “sell” myself. I was absolutely not star-forming region that hosts clouds of that, and certainly the most important prepared for this and I left the office different ages; the λ Orionis star-forming benefit that I will take away from working thinking that this will not be “the perfect region. In particular, the study of the at Paranal, is the interaction with col- match” to start a PhD and being pretty central cluster (Collinder 69) led to the leagues and visitors, and the effort re sure that he would not offer me the posi- ensemble of one of the most complete quired to understand what each service tion. Initial Mass Functions (IMF) for a young programme needs. All this, I believe, association. This allowed us to put has made me a more complete astrono- Funnily enough I did get an offer and I constraints on some formation scenarios mer. I think that focusing too much on could not have been more wrong. No proposed for brown dwarfs. Besides, one problem can cause a lack of per- PhD student–supervisor relationship is the detailed study of the population of spective that can prevent one from find- perfect, but I am convinced that I would sources still harbouring discs in the region ing a solution. Well, being at ESO Chile not be where I am now in my career allowed us to put caveats on the possi has had the completely opposite effect (with exactly the job that I wanted to have) bility that a supernova triggered the star on me; I will leave this country with without his influence. The first time we formation in the outer clouds. a wider view of astronomy that hopefully went to observe together on La Silla he will help me to find my answers. told me to stay outside for a while and let

The Messenger 147 – March 2012 51 Astronomical News

ESO

European Organisation for Astronomical Research in the Southern Hemisphere

ESO Studentship Programme

The research studentship programme of the European Southern Obser- The Outline of the Terms of Service for Students (http://www.eso.org/ vatory provides an outstanding opportunity for PhD students to experi- public/employment/student.html) provides some additional details on ence the exciting scientific environment at one of the world’s leading the employment conditions and benefits. observatories for a period of up to two years. If you are interested in enhancing your PhD experience through an ESO is the foremost intergovernmental astronomy organisation in extended stay at ESO please apply online at https://jobs.eso.org/. Refer- Europe. Its approximately 110 staff astronomers, 40 Fellows and 50 PhD ence letters to support your application should be sent to vacancy@eso. students conduct frontline research in fields ranging from exoplanets org for Garching and [email protected] for Chile. to cosmology, offering one of the most vibrant and stimulating scientific settings anywhere in the world. Please include the following documents in your application: – a Curriculum Vitae (including a list of publications, if any); ESO’s studentship positions are open to students enrolled in a PhD pro- – copies of your university transcript and certificate(s) or diploma(s); gramme in astronomy or related fields. Students accepted into the pro- – a summary of your master’s thesis project (if applicable) and ongoing gramme work on their doctoral project under the formal supervision projects, indicating the title and the supervisor (maximum half a page); of their home university, but they come to ESO to work and study under – an outline of the proposed PhD project highlighting the advantages of the co-supervision of an ESO staff astronomer, normally for a period coming to ESO (recommended one page, maximum two); of between one and two years. Studentships may be hosted either – two letters of reference, one from the home institute supervisor and at ESO’s Headquarters in Garching (Germany) or at ESO’s offices in one from the ESO local supervisor; Santiago (Chile), where two additional positions per year are provided for – a letter from the home institute that i) guarantees the financial support students enrolled in South American universities. for the remaining PhD period after the termination of the ESO studentship, ii) indicates whether the requirements to obtain the PhD degree Applicants and their home institute supervisors should agree upon and at the home institute have already been fulfilled. coordinate their research project jointly with their prospective ESO supervisor. For this purpose the ESO supervisor should be contacted All documents should be typed in English (but no translation is required well in advance of the application deadline (15 June 2012). A list of for the certificates and diplomas). potential ESO supervisors and their research interests can be found at http://www.eso.org/sci/activities/personnel.html. A list of PhD projects Closing date for applications is 15 June 2012, and review of the appli- currently being offered by ESO staff is available at http://www.eso.org/ cation documents (including the recommendation letters) will begin sci/activities/thesis-topics.html. immediately. Incomplete applications will not be considered.

It is highly recommended that applicants plan to start their PhD studies Candidates will be notified of the results of the selection process during at their home institute before continuing to develop their research pro- July–August 2012. Studentships typically begin between August and jects at ESO. December of the following year.

ESO Chile students have the opportunity to visit the observatories and For further information please contact Christina Stoffer (cstoffer@eso. to get involved in small technical projects aimed at giving insights into org). the observatory operations and instrumentation. Such involvement is also strongly encouraged for Garching students. In addition, students in Although recruitment preference will be given to nationals of ESO Mem- Garching may attend and benefit from the series of lectures delivered ber States (members are: Austria, Belgium, Brazil, the Czech Republic, in the framework of the International Max-Planck Research School on Denmark, Finland, France, Germany, Italy, the Netherlands, Portugal, Astrophysics. Spain, Sweden, Switzerland and United Kingdom) no nationality is in principle excluded. Students who are already enrolled in a PhD programme in the Munich area (e.g., at the International Max-Planck Research School on Astro- The post is equally open to suitably qualified female and male appli- physics or a Munich University) and who wish to apply for an ESO cants. studentship in Garching, should provide a compelling justification for their application.

52 The Messenger 147 – March 2012 Astronomical News

Personnel Movements

Arrivals (1 January–31 March 2012) Departures (1 January–31 March 2012)

Europe Europe Allouche, Fatme (RL) Instrumentation Engineer Ahumada, Andrea Veronica (AR) Fellow Correia dos Santos, Paula Cristina (P) Software Engineer Dall, Thomas (DK) User Support Astronomer Tobar Carrizo, Rodrigo Javier (RCH) Software Engineer Lablanche, Pierre-Yves (F) Student Tromp, Arnout (NL) Head of Contracts and Procurement Nielsen, Lars Holm (DK) Advanced Projects Coordinator Pedretti, Ettore (I) Instrument Scientist Chile Richichi, Andrea (I) Instrument Scientist Garrido, Hernan (CO) Student Parraguez, Diego (RCH) Telescope Instruments Operator Chile Rodón, Javier Adrián (AR) Fellow Amira, Maria Soledad (RCH) Administrative Assistant Romero, Rodrigo (RCH) Telescope Instruments Operator Carrasco, Mauricio (RCH) Student Tyndall, Amy (GB) Student Drass, Holger (D) Student Gutierrez, Fernando (RCH) Electronics Engineer Kuo, Caterina (RCH) Procurement Clerk Medina, Rolando (RCH) Electronics Engineer Nürnberger, Dieter (D) Operations Astronomer Olivares, Manuel (RCH) Telescope Instruments Operator ) twanight.org ESO/B. Tafreshi/TWAN (

The crescent Moon setting over the Paranal Observatory in Chile. The earthshine, which is Caption to image on page 54 and 55: Near-infrared sunlight scattered off the earth and illuminating the colour image of the Carina Nebula (NGC 3372) lunar disc, is well seen, as are the planets Mercury taken with HAWK-I on the VLT. Images in J-, H- and and Venus. See Release eso1210 for more details. Ks-bands were combined (colour-coded blue, green and red respectively). The bright star to lower left (south-east) is the massive binary η Carinae. The region to the north-west with many dust clouds is very actively forming stars. More details can be found in Release eso1208 and in the paper by T. Preibisch et al. (A&A, 530, A34, 2011).

The Messenger 147 – March 2012 53

ESO/T. Preibisch Annual Index 2011 (Nos. 143–146)

Subject Index TRAPPIST: TRAnsiting Planets and PlanetesImals Astronomical Science Small Telescope; Jehin, E.; Gillon, M.; Queloz, D.; Magain, P.; Manfroid, J.; Chantry, V.; Lendl, M.; Ozone: Twilit Skies, and (Exo-)planet Transits; The Organisation Hutsemékers, D.; Udry, S.; 145, 2 Fosbury, R.; Koch, G.; Koch, J.; 143, 27 CalVin 3 — A New Release of the ESO Calibrator Planet-forming Regions at the Highest Spectral and Adriaan Blaauw, 1914–2010; de Zeeuw, T.; Pottasch, Selection Tool for the VLT Interferometer; Spatial Resolution with VLT–CRIRES; Pontoppidan, S.; Wilson, R.; 143, 2 Wittkowski, M.; Ballester, P.; Bonneau, D.; Chelli, K. M.; van Dishoeck, E.; Blake, G. A.; Smith, R.; Brazil to Join ESO; de Zeeuw, T.; 143, 5 A.; Chesneau, O.; Cruzalèbes, P.; Duvert, G.; Brown, J.; Herczeg, G. J.; Bast, J.; Mandell, A.; Brazil’s Route to ESO Membership; Bruch, A.; 144, 2 Hummel, C.; Lafrasse, S.; Mella, G.; Melnick, J.; Smette, A.; Thi, W.-F.; Young, E. D.; Morris, M. R.; Mérand, A.; Mourard, D.; Percheron, I.; Sacuto, Dent, W.; Käufl, H. U.; 143, 32 S.; Shabun, K.; Stefl, S.; Vinther, J.; 145, 7 The SINFONI Integral Field Spectroscopy Survey for Telescopes and Instrumentation A New Massively-multiplexed Spectrograph for ESO; Galaxy Counterparts to Damped Lyman-α Sys- Ramsay, S.; Hammersley, P.; Pasquini, L.; 145, 10 tems; Péroux, C.; Bouché, N.; Kulkarni, V.; York, HARPSpol — The New Polarimetric Mode for MOONS: The Multi-Object Optical and Near-infrared D.; Vladilo, G.; 143, 37 HARPS; Piskunov, N.; Snik, F.; Dolgopolov, A.; Spectrograph; Cirasuolo, M.; Afonso, J.; Bender, The VLT VIMOS Lyman-break Galaxy Redshift Kochukhov, O.; Rodenhuis, M.; Valenti, J.; Jeffers, R.; Bonifacio, P.; Evans, C.; Kaper, L.; Oliva, E.; Survey — First Results; Shanks, T.; Bielby, R.; S.; Makaganiuk, V.; Johns-Krull, C.; Stempels, E.; Vanzi, L.; 145, 11 Infante, L.; 143, 42 Keller, C.; 143, 7 4MOST — 4-metre Multi-Object Spectroscopic A VISIR Mid-infrared Imaging Survey of Post-AGB Tests of Radiometric Phase Correction with ALMA; Telescope; de Jong, R.; 145, 14 Stars; Lagadec, E.; Verhoelst, T.; Mekarnia, D.; Nikolic, B.; Richer, J.; Bolton, R.; Hills, R.; 143, 11 ALMA Status and Science Verification Data; Testi, Suarez, O.; Zijlstra, A. A.; Bendjoya, P.; Szczerba, GRAVITY: Observing the Universe in Motion; L.; Zwaan, M.; 145, 17 R.; Chesneau, O.; Van Winckel, H.; Barlow, M. J.; Eisenhauer, F.; Perrin, G.; Brandner, W.; The VLT Survey Telescope Opens to the Sky: History Matsuura, M.; Bowey, J. E.; Lorenz-Martins, S.; Straubmeier, C.; Perraut, K.; Amorim, A.; Schöller, of a Commissioning; Capaccioli, M.; Schipani, P.; Gledhill, T.; 144, 21 M.; Gillessen, S.; Kervella, P.; Benisty, M.; Araujo- 146, 2 The VISTA Near-infrared YJKs Public Survey of the Hauck, C.; Jocou, L.; Lima, J.; Jakob, G.; Haug, OmegaCAM: ESO’s Newest Imager; Kuijken, K.; Magellanic Clouds System (VMC); M.-R., Cioni; M.; Clénet, Y.; Henning, T.; Eckart, A.; Berger, 146, 8 Clementini, G.; Girardi, L.; Guandalini, R.; J.-P.; Garcia, P.; Abuter, R.; Kellner, S.; Paumard, PIONIER: A Four-telescope Instrument for the VLTI; Gullieuszik, M.; Miszalski, B.; Moretti, M.-I.; T.; Hippler, S.; Fischer, S.; Moulin, T.; Villate, J.; Zins, G.; Lazareff, B.; Berger, J.-P.; Le Bouquin, Ripepi, V.; Rubele, S.; Bagheri, G.; Bekki, K.; Avila, G.; Gräter, A.; Lacour, S.; Huber, A.; Wiest, J.-B.; Jocou, L.; Rochat, S.; Haguenauer, P.; Cross, N.; de Blok, E.; de Grijs, R.; Emerson, J.; M.; Nolot, A.; Carvas, P.; Dorn, R.; Pfuhl, O.; Knudstrup, J.; Lizon, J.-L.; Millan-Gabet, R.; Evans, C.; Gibson, B.; Gonzales-Solares, E.; Gendron, E.; Kendrew, S.; Yazici, S.; Anton, S.; Traub, W.; Benisty, M.; Delboulbe, A.; Feautrier, Groenewegen, M.; Irwin, M.; Ivanov, V.; Lewis, J.; Jung, Y.; Thiel, M.; Choquet, É; Klein, R.; Teixeira, P.; Gillier, D.; Gitton, P.; Kern, P.; Kiekebusch, M.; Marconi, M.; Marquette, J.-B.; Mastropietro, C.; P.; Gitton, P.; Moch, D.; Vincent, F.; Kudryavtseva, Labeye, P.; Maurel, D.; Magnard, Y.; Micallef, M.; Moore, B.; Napiwotzki, R.; Naylor, T.; Oliveira, J.; N.; Ströbele, S.; Sturm, S.; Fédou, P.; Lenzen, R.; Michaud, L.; Moulin, T.; Popovic, D.; Roux, A.; Read, M.; Sutorius, E.; van Loon, J.; Wilkinson, Jolley, P.; Kister, C.; Lapeyrère, V.; Naranjo, V.; Ventura, N.; 146, 12 M.; Wood, P.; 144, 25 Lucuix, C.; Hofmann, R.; Chapron, F.; Neumann, Sparse Aperture Masking on Paranal; Lacour, S.; The Carina Dwarf Spheroidal Galaxy: A Goldmine U.; Mehrgan, L.; Hans, O.; Rousset, G.; Ramos, Tuthill, P.; Ireland, M.; Amico, P.; Girard, J.; 146, 18 for Cosmology and Stellar Astrophysics; Stetson, J.; Suarez, M.; Lederer, R.; Reess, J.-M.; Rohloff, P. B.; Monelli, M.; Fabrizio, M.; Walker, A.; Bono, R.-R.; Haguenauer, P.; Bartko, H.; Sevin, A.; G.; Buonanno, R.; Caputo, F.; Cassisi, S.; Corsi, Wagner, K.; Lizon, J.-L.; Rabien, S.; Collin, C.; C.; Dall’Ora, M.; Degl’Innocenti, S.; François, P.; Finger, G.; Davies, R.; Rouan, D.; Wittkowski, M.; Ferraro, I.; Gilmozzi, R.; Iannicola, G.; Merle, T.; Dodds-Eden, K.; Ziegler, D.; Cassaing, F.; Bonnet, Nonino, M.; Pietrinferni, A.; Moroni, P.P.; Pulone, H.; Casali, M.; Genzel, R.; Lena, P.; 143, 16 L.; Romaniello, M.; Thévenin, F.; 144, 32 The E-ELT has Successfully Passed the Phase B The Tenuous Atmospheres of Pluto and Triton Final Design Review; Gilmozzi, R.; Kissler-Patig, Explored by CRIRES on the VLT; Lellouch, E.; de M.; 143, 25 Bergh, C.; Sicardy, B.; Käufl, H.-U.; Smette, A.; The Science Impact of HAWK-I; Siebenmorgen, R.; 145, 20 Carraro, G.; Valenti, E.; Petr-Gotzens, M.; Bram- Molecular and Dusty Layers of Asymptotic Giant mer, G.; Garcia, E.; Casali, M.; 144, 9 Branch Stars Studied with the VLT Interferometer; p3d — A Data Reduction Tool for the Integral-field Wittkowski, M.; Karovicova, I.; Boboltz, D. A.; Modes of VIMOS and FLAMES; Sandin, C.; Fossat, E.; Ireland, M.; Ohnaka, K.; Scholz, M.; Weilbacher, P.; Streicher, O.; Walcher, C. J.; Roth, van Wyk, F.; Whitelock, P.; Wood, P. R.; Zijlstra, A. M. M.; 144, 13 A.; 145, 24 Phase 3 — Handling Data Products from ESO Public Science Results from the VISTA Survey of the Orion Surveys, Large Programmes and Other Contri Star-forming Region; Petr-Gotzens, M.; Alcalá, butions; Arnaboldi, M.; Retzlaff, J.; Slijkhuis, R.; J. M.; Briceño, C.; González-Solares, E.; Spezzi, Forchí, V.; Nunes, P.; Sforna, D.; Zampieri, S.; L.; Teixeira, P.; Osorio, M. R. Z.; Comerón, F.; Bierwirth, T.; Comerón, F.; Péron, M.; Romaniello, Emerson, J.; Hodgkin, S.; Hussain, G.; M.; Suchar, D.; 144, 17 McCaughrean, M.; Melnick, J.; Oliveira, J.; Ramsay, S.; Stanke, T.; Winston, E.; Zinnecker, H.; 145, 29

56 The Messenger 147 – March 2012 The VLT FLAMES Tarantula Survey; Evans, C.; Astronomical News New Staff at ESO: D. Mawet; 145, 52 Taylor, W.; Sana, H.; Hénault-Brunet, V.; Bagnoli, Fellows at ESO: S. Martin, J. Ascenso; 145, 53 T.; Bastian, N.; Bestenlehner, J.; Bonanos, A.; Report on the ESO Workshop “Spiral Structure in Personnel Movements; 145, 55 Bressert, E.; Brott, I.; Campbell, M.; Cantiello, M.; the Milky Way: Confronting Observations and Report on the Workshop “Fornax, Virgo, Coma et al: Carraro, G.; Clark, S.; Costa, E.; Crowther, P.; Theory”; Grosbøl, P.; Carraro, G.; Beletsky, Y.; Stellar Systems in High Density Environments”; de Koter, A.; de Mink, S.; Doran, E.; Dufton, P.; 143, 47 Arnaboldi, M.; 146, 36 Dunstall, P.; Garcia, M.; Gieles, M.; Gräfener, G.; Report on the Workshop “The First Year of Science Report on the Workshop “Feeding the Giants: ELTs Herrero, A.; Howarth, I.; Izzard, R.; Köhler, K.; with X-shooter”; Randich, S.; Covino, S.; Cristiani, in the Era of Surveys”; Calamida, A.; Verma, A.; Langer, N.; Lennon, D.; Apellániz, J. M.; Markova, S.; 143, 49 Hook, I.; Liske, J.; Kissler-Patig, M.; 146, 38 N.; Najarro, P.; Puls, J.; Ramirez, O.; Sabín- Report on the ESO Workshop “The Impact of Report on the ESO/MPE/MPA/ExcellenceCluster/ Sanjulián, C.; Simón-Díaz, S.; Smartt, S.; Stroud, Herschel Surveys on ALMA Early Science”; Testi, LMU Joint Astronomy Workshop “The Formation V.; van Loon, J.; Vink, J. S.; Walborn, N.; 145, 33 L.; Pilbratt, G.; Andreani, P.; 143, 52 and Early Evolution of Very Low-mass Stars and The SINS and zC-SINF Surveys: The Growth of Site Surveys for the Extremely Large Telescopes Brown Dwarfs”; Petr-Gotzens, M.; Testi, L.; 146, Massive Galaxies at z ~ 2 through Detailed and More: Sharing the Experience and the Data; 41 Kinematics and Star Formation with SINFONI; Sarazin, M.; 143, 56 Brazilian Teachers and Students Visit Paranal and Förster Schreiber, N. M.; Genzel, R.; Renzini, A.; ESO’s Hidden Treasures Competition; Hainaut, O.; ALMA; West, M.; 146, 44 Tacconi, L. J.; Lilly, S. J.; Bouché, N.; Burkert, A.; Sandu, O.; Christensen, L. L.; 143, 57 ESO Presence at the Astronomical Society of Brazil Buschkamp, P.; Carollo, C. M.; Cresci, G.; Davies, Fellows at ESO: A. Ahumada, B. Venemans; 143, 59 Annual Meeting; Liske, J.; 146, 45 R.; Eisenhauer, F.; Genel, S.; Gillessen, S.; Hicks, Personnel Movements; 143, 60 First ESO Public Release of Data Products from the E. K. S.; Jones, T.; Kurk, J.; Lutz, D.; Mancini, C.; ESO Studentship Programme; 143, 61 VISTA Public Surveys; Arnaboldi, M.; Retzlaff, J.; Naab, T.; Newman, S.; Peng, Y.; Shapiro, K. L.; Announcement of the ESO/MPE/MPA/Excellence 146, 45 Shapley, A. E.; Sternberg, A.; Vergani, D.; Wuyts, Cluster/USM Joint Astronomy Workshop “Forma- Announcement of the Workshop “Astronomical Data S.; Zamorani, G.; Arimoto, N.; Ceverino, D.; tion and Early Evolution of Very Low Mass Stars Analysis 7th Conference”; 146, 46 Cimatti, A.; Daddi, E.; Dekel, A.; Erb, D. K.; Kong, and Brown Dwarfs”; 143, 62 Introduction of Calibration Selection via the ESO X.; Mainieri, V.; Maraston, C.; McCracken, H. J.; Announcement of the ESO Workshop Science Archive Facility and Discontinuation of PI Mignoli, M.; Oesch, P.; Onodera, M.; Pozzetti, L.; “Multiwavelength Views of the ISM in High-red- Packages; 146, 47 Steidel, C. C.; Verma, A.; 145, 39 shift Galaxies”; 143, 62 Announcement of the Joint ESO/IAG/USP Workshop Resolving the Inner Regions of Circumstellar Discs Announcement of the Workshop “Feeding the “Circumstellar Dynamics at High Resolution”; 146, with VLT/NACO Polarimetric Differential Imaging; Giants: ELTs in the Era of Surveys”; 143, 63 47 Quanz, S. P.; Schmid, H. M.; Birkmann, S. M.; Report on the Workshop “ALMA Community Days: Fellows at ESO: O. Panić, D. Gadotti; 146, 48 Apai, D.; Wolf, S.; Brandner, W.; Meyer, M. R.; Towards Early Science”; Randall, S.; Testi, L.; 144, Personnel Movements; 146, 49 Henning, T.; 146, 25 39 E-ELT Project Manager and Head of the E-ELT X-shooter Finds an Extremely Primitive Star; Caffau, Report on the “ALMA Early Science Massive Star Division; 146, 50 E.; Bonifacio, P.; François, P.; Sbordone, L.; Formation Workshop”; Longmore, S.; Testi, L.; Monaco, L.; Spite, M.; Spite, F.; Ludwig, H.-G.; Klaassen, P.; 144, 41 Cayrel, R.; Zaggia, S.; Hammer, F.; Randich, S.; Report on the ESO Workshop “Dynamics of Molaro, P.; Hill, V.; 146, 28 Low-mass Stellar Systems: From Star Clusters to Evolution of the Observed Ly-alpha Luminosity Dwarf Galaxies”; Mieske, S.; Gieles, M.; 144, 44 Function from z = 65 to z = 77: Evidence for the Report on the Workshop “The Evolution of Compact Epoch of Re-ionisation?; Clément, B.; Cuby, Binaries”; Schmidtobreick, L.; Schreiber, M. R.; J.-G.; Courbin, F.; Fontana, A.; Freudling, W.; 144, 47 Fynbo, J.; Gallego, J.; Hibon, P.; Kneib, J.-P.; Le ESO Participates in Germany’s Girls’ Day Activities; Fèvre, O.; Lidman, C.; McMahon, R.; Milvang- Pierce-Price, D.; 144, 49 Jensen, B.; Moller, P.; Nilsson, K. K.; Pentericci, Announcement of the ESO Workshop “Ten Years of L.; Venemans, B.; Villar, V.; Willis, J.; 146, 31 VLTI: From First Fringes to Core Science”; 144, 49 Personnel Movements; 144, 51 Fellows at ESO: C. Goddi, P. Kabath; 144, 52 Report on the “Garching ESO Fellow Days – 2011”; Emsellem, E.; Klaassen, P.; West, M.; 144, 53 ESO Fellowship Programme 2011/2012; 144, 55 Report on the Workshop “Multiwavelength Views of the ISM in High-redshift Galaxies”; Wagg, J.; De Breuck, C.; 145, 46 In memoriam Alan Moorwood; de Zeeuw, T.; Leibundgut, B.; Fosbury, R.; D’Odorico, S.; 145, 49 In memoriam Carlo Izzo; de Zeeuw, T.; Péron, M.; 145, 51

The Messenger 147 – March 2012 57 Author Index E G

Eisenhauer, F.; Perrin, G.; Brandner, W.; Straubmeier, Gilmozzi, R.; Kissler-Patig, M.; The E-ELT has A C.; Perraut, K.; Amorim, A.; Schöller, M.; Successfully Passed the Phase B Final Design Gillessen, S.; Kervella, P.; Benisty, M.; Araujo- Review; 143, 25 Arnaboldi, M.; Retzlaff, J.; Slijkhuis, R.; Forchí, V.; Hauck, C.; Jocou, L.; Lima, J.; Jakob, G.; Haug, Grosbøl, P.; Carraro, G.; Beletsky, Y.; Report on the Nunes, P.; Sforna, D.; Zampieri, S.; Bierwirth, T.; M.; Clénet, Y.; Henning, T.; Eckart, A.; Berger, ESO Workshop “Spiral Structure in the Milky Way: Comerón, F.; Péron, M.; Romaniello, M.; Suchar, J.-P.; Garcia, P.; Abuter, R.; Kellner, S.; Paumard, Confronting Observations and Theory”; 143, 47 D.; Phase 3 — Handling Data Products from ESO T.; Hippler, S.; Fischer, S.; Moulin, T.; Villate, J.; Public Surveys, Large Programmes and Other Avila, G.; Gräter, A.; Lacour, S.; Huber, A.; Wiest, Contributions; 144, 17 M.; Nolot, A.; Carvas, P.; Dorn, R.; Pfuhl, O.; H Arnaboldi, M.; Report on the Workshop “Fornax, Gendron, E.; Kendrew, S.; Yazici, S.; Anton, S.; Virgo, Coma et al: Stellar Systems in High Density Jung, Y.; Thiel, M.; Choquet, É; Klein, R.; Teixeira, Hainaut, O.; Sandu, O.; Christensen, L. L.; ESO’s Environments”; 146, 36 P.; Gitton, P.; Moch, D.; Vincent, F.; Kudryavtseva, Hidden Treasures Competition; 143, 57 Arnaboldi, M.; Retzlaff, J.; First ESO Public Release N.; Ströbele, S.; Sturm, S.; Fédou, P.; Lenzen, R.; of Data Products from the VISTA Public Surveys; Jolley, P.; Kister, C.; Lapeyrère, V.; Naranjo, V.; 146, 45 Lucuix, C.; Hofmann, R.; Chapron, F.; Neumann, J U.; Mehrgan, L.; Hans, O.; Rousset, G.; Ramos, J.; Suarez, M.; Lederer, R.; Reess, J.-M.; Rohloff, Jehin, E.; Gillon, M.; Queloz, D.; Magain, P.; B R.-R.; Haguenauer, P.; Bartko, H.; Sevin, A.; Manfroid, J.; Chantry, V.; Lendl, M.; Hutsemékers, Wagner, K.; Lizon, J.-L.; Rabien, S.; Collin, C.; D.; Udry, S.; TRAPPIST: TRAnsiting Planets and Bruch, A.; Brazil’s Route to ESO Membership; 144, 2 Finger, G.; Davies, R.; Rouan, D.; Wittkowski, M.; PlanetesImals Small Telescope; 145, 2 Dodds-Eden, K.; Ziegler, D.; Cassaing, F.; Bonnet, H.; Casali, M.; Genzel, R.; Lena, P.; GRAVITY: C Observing the Universe in Motion; 143, 16 K Emsellem, E.; Klaassen, P.; West, M.; Report on the Caffau, E.; Bonifacio, P.; François, P.; Sbordone, L.; “Garching ESO Fellow Days – 2011”; 144, 53 Kuijken, K.; OmegaCAM: ESO’s Newest Imager; Monaco, L.; Spite, M.; Spite, F.; Ludwig, H.-G.; Evans, C.; Taylor, W.; Sana, H.; Hénault-Brunet, V.; 146, 8Balloons over the La Silla Paranal Observa- Cayrel, R.; Zaggia, S.; Hammer, F.; Randich, S.; Bagnoli, T.; Bastian, N.; Bestenlehner, J.; Bonanos, tory; 141, 9 Molaro, P.; Hill, V.; X-shooter Finds an Extremely A.; Bressert, E.; Brott, I.; Campbell, M.; Cantiello, Primitive Star; 146, 28 M.; Carraro, G.; Clark, S.; Costa, E.; Crowther, P.; Calamida, A.; Verma, A.; Hook, I.; Liske, J.; Kissler- de Koter, A.; de Mink, S.; Doran, E.; Dufton, P.; L Patig, M.; Report on the Workshop “Feeding the Dunstall, P.; Garcia, M.; Gieles, M.; Gräfener, G.; Giants: ELTs in the Era of Surveys”; 146, 38 Herrero, A.; Howarth, I.; Izzard, R.; Köhler, K.; Lacour, S.; Tuthill, P.; Ireland, M.; Amico, P.; Girard, Capaccioli, M.; Schipani, P.; The VLT Survey Langer, N.; Lennon, D.; Apellániz, J. M.; Markova, J.; Sparse Aperture Masking on Paranal; 146, 18 Telescope Opens to the Sky: History of a Com- N.; Najarro, P.; Puls, J.; Ramirez, O.; Sabín- Lagadec, E.; Verhoelst, T.; Mekarnia, D.; Suarez, O.; missioning; 146, 2 Sanjulián, C.; Simón-Díaz, S.; Smartt, S.; Stroud, Zijlstra, A. A.; Bendjoya, P.; Szczerba, R.; Cirasuolo, M.; Afonso, J.; Bender, R.; Bonifacio, P.; V.; van Loon, J.; Vink, J. S.; Walborn, N.; The VLT Chesneau, O.; Van Winckel, H.; Barlow, M. J.; Evans, C.; Kaper, L.; Oliva, E.; Vanzi, L.; MOONS: FLAMES Tarantula Survey; 145, 33 Matsuura, M.; Bowey, J. E.; Lorenz-Martins, S.; The Multi-Object Optical and Near-infrared Spec- Gledhill, T.; A VISIR Mid-infrared Imaging Survey trograph; 145, 11 of Post-AGB Stars; 144, 21 Clément, B.; Cuby, J.-G.; Courbin, F.; Fontana, A.; F Lellouch, E.; de Bergh, C.; Sicardy, B.; Käufl, Freudling, W.; Fynbo, J.; Gallego, J.; Hibon, P.; H.-U.; Smette, A.; The Tenuous Atmospheres of Kneib, J.-P.; Le Fèvre, O.; Lidman, C.; McMahon, Förster Schreiber, N. M.; Genzel, R.; Renzini, A.; Pluto and Triton Explored by CRIRES on the VLT; R.; Milvang-Jensen, B.; Moller, P.; Nilsson, K. K.; Tacconi, L. J.; Lilly, S. J.; Bouché, N.; Burkert, A.; 145, 20 Pentericci, L.; Venemans, B.; Villar, V.; Willis, J.; Buschkamp, P.; Carollo, C. M.; Cresci, G.; Davies, Liske, J.; ESO Presence at the Astronomical Society Evolution of the Observed Ly-alpha Luminosity R.; Eisenhauer, F.; Genel, S.; Gillessen, S.; Hicks, of Brazil Annual Meeting; 146, 45 Function from z = 65 to z = 77: Evidence for the E. K. S.; Jones, T.; Kurk, J.; Lutz, D.; Mancini, C.; Longmore, S.; Testi, L.; Klaassen, P.; Report on the Epoch of Re-ionisation?; 146, 31 Naab, T.; Newman, S.; Peng, Y.; Shapiro, K. L.; “ALMA Early Science Massive Star Formation Shapley, A. E.; Sternberg, A.; Vergani, D.; Wuyts, Workshop”; 144, 41 S.; Zamorani, G.; Arimoto, N.; Ceverino, D.; D Cimatti, A.; Daddi, E.; Dekel, A.; Erb, D. K.; Kong, X.; Mainieri, V.; Maraston, C.; McCracken, H. J.; M de Jong, R.; 4MOST — 4-metre Multi-Object Mignoli, M.; Oesch, P.; Onodera, M.; Pozzetti, L.; Spectroscopic Telescope; 145, 14 Steidel, C. C.; Verma, A.; The SINS and zC-SINF M.-R., Cioni; Clementini, G.; Girardi, L.; Guandalini, de Zeeuw, T.; Pottasch, S.; Wilson, R.; Adriaan Surveys: The Growth of Massive Galaxies at z ~ 2 R.; Gullieuszik, M.; Miszalski, B.; Moretti, M.-I.; Blaauw, 1914–2010; 143, 2 through Detailed Kinematics and Star Formation Ripepi, V.; Rubele, S.; Bagheri, G.; Bekki, K.; de Zeeuw, T.; Brazil to Join ESO; 143, 5 with SINFONI; 145, 39 Cross, N.; de Blok, E.; de Grijs, R.; Emerson, J.; de Zeeuw, T.; Leibundgut, B.; Fosbury, R.; Fosbury, R.; Koch, G.; Koch, J.; Ozone: Twilit Skies, Evans, C.; Gibson, B.; Gonzales-Solares, E.; D’Odorico, S.; In memoriam Alan Moorwood; and (Exo-)planet Transits; 143, 27 Groenewegen, M.; Irwin, M.; Ivanov, V.; Lewis, J.; 145, 49 Marconi, M.; Marquette, J.-B.; Mastropietro, C.; de Zeeuw, T.; Péron, M.; In memoriam Carlo Izzo; Moore, B.; Napiwotzki, R.; Naylor, T.; Oliveira, J.; 145, 51 Read, M.; Sutorius, E.; van Loon, J.; Wilkinson, M.; Wood, P.; The VISTA Near-infrared YJKs Public Survey of the Magellanic Clouds System (VMC); 144, 25 Mieske, S.; Gieles, M.; Report on the ESO Workshop “Dynamics of Low-mass Stellar Systems: From Star Clusters to Dwarf Galaxies”; 144, 44

58 The Messenger 147 – March 2012 N R W

Nikolic, B.; Richer, J.; Bolton, R.; Hills, R.; Tests of Ramsay, S.; Hammersley, P.; Pasquini, L.; A New Wagg, J.; De Breuck, C.; Report on the Workshop Radiometric Phase Correction with ALMA; 143, 11 Massively-multiplexed Spectrograph for ESO; “Multiwavelength Views of the ISM in High- 145, 10 redshift Galaxies”; 145, 46 Randall, S.; Testi, L.; Report on the Workshop West, M.; Brazilian Teachers and Students Visit P “ALMA Community Days: Towards Early Science”; Paranal and ALMA; 146, 44 144, 39 Wittkowski, M.; Ballester, P.; Bonneau, D.; Chelli, A.; Péroux, C.; Bouché, N.; Kulkarni, V.; York, D.; Vladilo, Randich, S.; Covino, S.; Cristiani, S.; Report on the Chesneau, O.; Cruzalèbes, P.; Duvert, G.; G.; The SINFONI Integral Field Spectroscopy Sur- Workshop “The First Year of Science with Hummel, C.; Lafrasse, S.; Mella, G.; Melnick, J.; vey for Galaxy Counterparts to Damped Lyman-α X-shooter”; 143, 49 Mérand, A.; Mourard, D.; Percheron, I.; Sacuto, Systems; 143, 37 S.; Shabun, K.; Stefl, S.; Vinther, J.; CalVin 3 — A Petr-Gotzens, M.; Alcalá, J. M.; Briceño, C.; New Release of the ESO Calibrator Selection Tool González-Solares, E.; Spezzi, L.; Teixeira, P.; S for the VLT Interferometer; 145, 7 Osorio, M. R. Z.; Comerón, F.; Emerson, J.; Wittkowski, M.; Karovicova, I.; Boboltz, D. A.; Hodgkin, S.; Hussain, G.; McCaughrean, M.; Sandin, C.; Weilbacher, P.; Streicher, O.; Walcher, C. Fossat, E.; Ireland, M.; Ohnaka, K.; Scholz, M.; Melnick, J.; Oliveira, J.; Ramsay, S.; Stanke, T.; J.; Roth, M. M.; p3d — A Data Reduction Tool for van Wyk, F.; Whitelock, P.; Wood, P. R.; Zijlstra, A. Winston, E.; Zinnecker, H.; Science Results from the Integral-field Modes of VIMOS and FLAMES; A.; Molecular and Dusty Layers of Asymptotic the VISTA Survey of the Orion Star-forming 144, 13 Giant Branch Stars Studied with the VLT Inter Region; 145, 29 Sarazin, M.; Site Surveys for the Extremely Large ferometer; 145, 24 Petr-Gotzens, M.; Testi, L.; Report on the ESO/MPE/ Telescopes and More: Sharing the Experience MPA/ExcellenceCluster/LMU Joint Astronomy and the Data; 143, 56 Workshop “The Formation and Early Evolution of Schmidtobreick, L.; Schreiber, M. R.; Report on the Z Very Low-mass Stars and Brown Dwarfs”; 146, 41 Workshop “The Evolution of Compact Binaries”; Pierce-Price, D.; ESO Participates in Germany’s 144, 47 Zins, G.; Lazareff, B.; Berger, J.-P.; Le Bouquin, Girls’ Day Activities; 144, 49 Shanks, T.; Bielby, R.; Infante, L.; The VLT VIMOS J.-B.; Jocou, L.; Rochat, S.; Haguenauer, P.; Piskunov, N.; Snik, F.; Dolgopolov, A.; Kochukhov, Lyman-break Galaxy Redshift Survey — First Knudstrup, J.; Lizon, J.-L.; Millan-Gabet, R.; O.; Rodenhuis, M.; Valenti, J.; Jeffers, S.; Results; 143, 42 Traub, W.; Benisty, M.; Delboulbe, A.; Feautrier, P.; Makaganiuk, V.; Johns-Krull, C.; Stempels, E.; Siebenmorgen, R.; Carraro, G.; Valenti, E.; Gillier, D.; Gitton, P.; Kern, P.; Kiekebusch, M.; Keller, C.; HARPSpol — The New Polarimetric Petr-Gotzens, M.; Brammer, G.; Garcia, E.; Casali, Labeye, P.; Maurel, D.; Magnard, Y.; Micallef, M.; Mode for HARPS; 143, 7 M.; The Science Impact of HAWK-I; 144, 9 Michaud, L.; Moulin, T.; Popovic, D.; Roux, A.; Pontoppidan, K. M.; van Dishoeck, E.; Blake, G.A.; Stetson, P. B.; Monelli, M.; Fabrizio, M.; Walker, A.; Ventura, N.; PIONIER: A Four-telescope Instru- Smith, R.; Brown, J.; Herczeg, G. J.; Bast, J.; Bono, G.; Buonanno, R.; Caputo, F.; Cassisi, S.; ment for the VLTI; 146, 12 Mandell, A.; Smette, A.; Thi, W.-F.; Young, E.D.; Corsi, C.; Dall’Ora, M.; Degl’Innocenti, S.; François, Morris, M. R.; Dent, W.; Käufl, H. U.; Planet-form- P.; Ferraro, I.; Gilmozzi, R.; Iannicola, G.; Merle, T.; ing Regions at the Highest Spectral and Spatial Nonino, M.; Pietrinferni, A.; Moroni, P.P.; Pulone, Resolution with VLT–CRIRES; 143, 32 L.; Romaniello, M.; Thévenin, F.; The Carina Dwarf Spheroidal Galaxy: A Goldmine for Cosmology and Stellar Astrophysics; 144, 32 Q

Quanz, S. P.; Schmid, H. M.; Birkmann, S. M.; Apai, T D.; Wolf, S.; Brandner, W.; Meyer, M. R.; Henning, T.; Resolving the Inner Regions of Circumstellar Testi, L.; Pilbratt, G.; Andreani, P.; Report on the Discs with VLT/NACO Polarimetric Differential ESO Workshop “The Impact of Herschel Surveys Imaging; 146, 25 on ALMA Early Science”; 143, 52 Testi, L.; Zwaan, M.; ALMA Status and Science Verification Data; 145, 17

The Messenger 147 – March 2012 59 ESO, the European Southern Observa- Contents tory, is the foremost intergovernmental astronomy organisation in Europe. It Telescopes and Instrumentation is supported by 15 countries: Austria, F. Comerón et al. – High-speed Bandwidth between Europe and Paranal: Belgium, Brazil, the Czech Republic, EVALSO Demonstration Activities and Integration into Operations 2 Denmark, France, Finland, Germany, R. Bacon et al. – News of the MUSE 4 Italy, the Netherlands, Portugal, Spain, D. Schwan et al. – APEX–SZ: The Atacama Pathfinder EXperiment Sweden, Switzerland and the United Sunyaev–Zel’dovich Instrument 7 Kingdom. ESO’s programme is focused on the design, construction and opera- Astronomical Science tion of powerful ground-based observ- J. Storm et al. – Determining the Cepheid Period–Luminosity Relation Using ing facilities. ESO operates three obser- Distances to Individual Cepheids from the Near-infrared Surface Brightness vatories in Chile: at La Silla, at Paranal, Method 14 site of the Very Large Telescope, and G. Fiorentino et al. – Resolved Stellar Populations with MAD: Preparing at Llano de Chajnantor. ESO is the for the Era of Extremely Large Telescopes 17 European partner in the Atacama Large N. Lützgendorf et al. – The Search for Intermediate-mass Black Holes Millimeter/submillimeter Array (ALMA) in Globular Clusters 21 under construction at Chajnantor. G. Gilmore et al. – The Gaia-ESO Public Spectroscopic Survey 25 Currently ESO is engaged in the design T. Contini et al. – Teenage Galaxies 32 of the European Extremely Large Telescope. Astronomical News L. Burtscher et al. – Report on the Workshop “Ten Years of VLTI: The Messenger is published, in hard- From First Fringes to Core Science” 38 copy and electronic form, four times a U. Grothkopf, S. Meakins – ESO Telescope Bibliography: year: in March, June, September and New Public Interface 41 December. ESO produces and distrib- X. Barcons – Greetings from the ESO Council 43 utes a wide variety of media connected M. West, E. Emsellem – Report on the ESO Fellows Days in Chile 2011 44 to its activities. For further information, Call for Nominations for the European Extremely Large Telescope Project including postal subscription to The Science Team 45 Messenger, contact the ESO education ESO Celebrates its 50th Anniversary 46 and Public Outreach Department at the Announcement of the Conference “ESO@50 – The First 50 Years of ESO” 47 following address: Announcement of the ESO Workshop “Ecology of Blue Straggler Stars” 47 Announcement of the ESO Workshop “Science from the Next Generation ESO Headquarters Imaging and Spectroscopic Surveys” 48 Karl-Schwarzschild-Straße 2 Announcement of the ALMA Community Days: Early Science in Cycle 1 48 85748 Garching bei München Announcement of the NEON Observing School 2012 49 Germany Fellows at ESO – M. Westmoquette, A. Bayo 50 Phone +498932006-0 ESO Studentship Programme 52 [email protected] Personnel Movements 53

The Messenger: Annual Index 2011 (Nos. 143–146) 56 Editor: Jeremy R. Walsh; Design, Production: Jutta Boxheimer; Layout, Typesetting: Mafalda Martins; Graphics: Roberto Duque www.eso.org/messenger/

Printed by Peschke Druck Schatzbogen 35, 81805 München Germany Front cover: The Helix Nebula, NGC 7293, is shown in the near-infrared from

images taken with the VISTA survey telescope in Y-, J- and Ks-bands (1.02, 1.65 Unless otherwise indicated, all images and 2.15 μm respectively). The Helix Nebula, at a distance of 220 parsecs, is one of in The Messenger are courtesy of ESO, the closest planetary nebulae and in consequence displays a wealth of fine detail except authored contributions which not observed in more distant planetary nebulae. The many compact knots, known are courtesy of the respective authors. from optical observations, emit strongly in molecular hydrogen (detected in the

Ks-band image) and trace out in filigree the helix morphology. The outer filament © ESO 2012 (upper left, north-east) is part of an even larger structure measuring about 2.2 par- ISSN 0722-6691 secs across. See Release eso1205. Credit: ESO/VISTA/J. Emerson. Acknowledge- ment: Cambridge Astronomical Survey Unit