arXiv:1012.1551v1 [astro-ph.CO] 7 Dec 2010 2 November 2010 Received 3. December 2010 Accepted al Serra Paolo afel Morganti Raffaella oe .Davies L. Roger aehKhochfar Sadegh ihlsScott Nicholas .Bacon R. ihl Cappellari Michele criteria selection and goals science galaxies: early-type h ATLAS The o.Nt .Ato.Soc. Astron. R. Not. Mon. 16 15 14 13 12 11 3 2 1 10 9 8 7 6 5 Andr Charles avenue 9 4 Lyon, Sup´erieure de Normale Ecole and c nvri´ yn1 bevtied yn eted Recherc de Centre Lyon, de Observatoire 1, Universit´e Lyon Karl-Schwarzschild-Str. Observatory, Southern Den European Oxford, of University Astrophysics, of Sub-department treah edn ednUiest,Psbs91,2300 9513, Postbus University, Leiden Universi Leiden, Sterrewacht CNRS CEA/IRFU/SAp Paris-Saclay, Cali AIM of Laboratoire University Hall, Tech Campbell Astronomy, and of Mining Department of Institute Mexico New Department, Physics Groningen, of University Institute, A‘o Astronomical N. Kapteyn 670 Centre, Operations Northern Observatory, Gemini ulpIsiuefrAtooy&Atohsc,University Astrophysics, & Astronomy for Institute Hertfords Dunlap of University Research, Astrophysics for Centre Karl-Schwarzschil f¨ur Astrophysik, Institut Postb Max-Planck (ASTRON), Astronomy Radio for Institute Netherlands European Facility, Coordinating European Telescope Space Bo PO Physik, f¨ur extraterrestrische Institut Max-Planck aoaor I,CADMCR-nvri ai ieo,D Diderot, Paris CEA/DSM-CNRS-Universit AIM, Laboratoire 01RAS 2011 3 e Blitz Leo , 13 n neMreWeijmans Anne-Marie and , 1 000 3D .A ede Kleijn Verdoes A. G. , 1 –7(01 rne eebr21 M L (MN 2010 December 8 Printed (2011) 1–27 , ioh .Davis A. Timothy , 11 rjc .Avlm-iie apeo 6 nearby 260 of sample volume-limited A I. – project 5 aadKuntschner Harald , 1 , ⋆ 13 7 rcEmsellem Eric , aieBois Maxime , hrtnNaab Thorsten , -t.1 54 acig Germany Garching, 85741 1, d-Str. otu 0,90 VGoign h Netherlands The Groningen, AV 9700 800, Postbus 32 -57 acig Germany Garching, D-85478 1312, x ,878Grhn,Germany Garching, 85748 2, ie afil,HrsA19B UK 9AB, AL1 Herts Hatfield, hire, sWlisnBidn,KbeRa,Ofr X 3RH OX1 Oxford Road, Keble Building, Wilkinson ys ALie,teNetherlands the Leiden, RA eAtohsqed Lyon de Astrophysique he fTrno 0S.Gog tet oot,O 5 H,Canada 3H4, M5S ON Toronto, Street, George St. 50 Toronto, of ona ekly A970 USA 94720, CA Berkeley, fornia, otenOsraoy alShazcidSr ,878G 85748 2, Karl-Schwarzschild-Str. Observatory, Southern s2 90A wneo,TeNetherlands The Dwingeloo, AA 7990 2, us ouPae io I970 USA 96720, HI Hilo, Place, hoku ooy oor,N 70,USA 87801, NM Socorro, nology, e -93 an-ei aa,France Laval, Saint-Genis ´e, F-69230 1 2 pi/evc ’srpyiu,CASca,911Gif-su 91191 CEA-Saclay, d’Astrophysique, apnia/Service ´ ai ieo,911GfsrYet ee,France Cedex, Gif-sur-Yvette 91191 Diderot, t´e Paris 2 , .T eZeeuw de T. P. , 5 3 , 14 3 iaM Young M. Lisa , Fr , 12 ao Krajnovi Davor , o Oosterloo Tom , ireYe Lablanche Pierre-Yves , 16 ed ´ † rcBournaud eric ´ A T E tl l v2.2) file style X 2 , 9 6 ireAanDuc Pierre-Alain , ahrn Alatalo Katherine , 5 c ´ , 2 13 ihr .McDermid M. Richard , 8 acSarzi Marc , .Bureau M. , 3 , rhn,Germany arching, -vteCdx France Cedex, r-Yvette 15 1 , , 10 7 , , 4 , 2 M. Cappellari et al.
ABSTRACT The ATLAS3D project is a multi-wavelength survey combined with a theoretical modelling effort. The observations span from the radio to the millimeter and optical, and provide multi- colour imaging, two-dimensional kinematics of the atomic (H I), molecular (CO) and ionized gas (Hβ, [O III] and [N I]), together with the kinematics and population of the stars (Hβ, Fe5015 and Mg b), for a carefully selected, volume-limited (1.16 × 105 Mpc3) sample of 260 early-type (elliptical E and lenticular S0) galaxies (ETGs). The models include semi-analytic, N-body binary mergers and cosmological simulations of galaxy formation. Here we present the science goals for the project and introduce the galaxy sample and the selection criteria. The sample consists of nearby (D < 42 Mpc) morphologically-selected ETGs extracted from a parent sample of 871 galaxies (8% E, 22% S0 and 70% spirals) brighter than MK < −21.5 > 6 109 mag (stellar mass M⋆ ∼ × M⊙). We analyze possible selection biases and we conclude that the parent sample is essentially complete and statistically representative of the nearby galaxy population. We present the size-luminosity relation for the spirals and ETGs and show that the ETGs in the ATLAS3D sample define a tight red sequence in a colour-magnitude diagram, with few objects in the transition from the blue cloud. We describe the strategy of the SAURON integral-field observations and the extraction of the stellar kinematics with the pPXF −1 −1 method. We find typical 1σ errors of ∆V ≈ 6 km s , ∆σ ≈ 7 km s , ∆h3 ≈ ∆h4 ≈ 0.03 in the mean velocity, the velocity dispersion and Gauss-Hermite (GH) moments for galaxies > 120 −1 40 with effective dispersion σe ∼ km s . For galaxies with lower σe (≈ % of the sample) the GH moments are graduallypenalized by pPXF towards zero to suppress the noise produced by the spectral under-sampling and only V and σ can be measured. We give an overview of the characteristics of the other main datasets already available for our sample and of the ongoing modeling projects. Key words: galaxies: classification – galaxies: elliptical and lenticular, cD – galaxies: evolu- tion – galaxies: formation – galaxies: structure – galaxies: kinematics and dynamics
1 INTRODUCTION important contributions of the Sloan Digital Sky Survey (SDSS, York et al. 2000) was to firmly establish a statistically significant 1.1 Scientific background bimodality in the colour distribution of local galaxies, such that Observations of high-redshift galaxies and the cosmic microwave they can be clearly separated in a so-called ‘blue cloud’, gener- background (Spergel et al. 2007) have revealed the Universe to ally consisting of star-forming spiral galaxies, and a ‘red sequence’, be dominated by dark matter and dark energy (Riess et al. 1998; mostly of non-star-forming ETGs (Strateva et al. 2001; Baldry et al. Perlmutter et al. 1999), providing a working paradigm for the for- 2004). Accurately quantifying this bimodality, and the realization mation of structure (e.g. Springel et al. 2005). However, the mech- that it can be traced back in time to higher redshift (Bell et al. 2004; anisms that form the luminous content of the dark-matter poten- Faber et al. 2007), allowed a dramatic improvement in the detailed tial (i.e. the stars and galaxies that we observe) remain the key un- testing of galaxy formation scenarios. knowns of modern extra-galactic astronomy. These processes are driven by the hydrodynamics and chemistry of the gas, combined The bimodality can only be explained with the existence with complex radiative feedback processes. High-redshift observa- of a mechanism, which suppresses episodes of intense star for- tions alone are not sufficient to constrain these processes, lacking mation by evacuating gas from the system, resulting in a rapid spectral information and spatial resolution (Faber et al. 2007). It is transition of galaxies from the blue cloud to the red sequence therefore necessary to complement these studies with detailed anal- (Springel et al. 2005; Faber et al. 2007). Many simulation groups ysis of nearby objects, tracing the fossil record of the formation have reproduced the bimodality qualitatively, though with rather process. Early-type (elliptical E and lenticular S0) galaxies (ETGs) different assumptions for the star formation and feedback pro- are especially useful as they are old, have smaller levels of star for- cesses (Granato et al. 2004; Di Matteo et al. 2005; Bower et al. mation and limited amount of dust, which simplifies the interpre- 2006; Cattaneo et al. 2006; Croton et al. 2006). A generic feature tation of the observations. Significant progress has been made in of these models is that red-sequence galaxies form by dissipa- this direction in the past few decades, building on the classic obser- tional ‘wet mergers’ of gas-rich blue-cloud galaxies, followed by vational works that still capture much of our understanding of the quenching of the resulting intense star-formation by rapid ejec- structure of local ETGs (e.g. Hubble 1936; Faber & Jackson 1976; tion of the gas, caused by the feedback from a central supermas- Davies et al. 1983; Dressler et al. 1987; Djorgovski & Davis 1987; sive black hole, supernovae winds, by shock heating of the gas in Bender et al. 1992; Kormendy & Richstone 1995). the most massive halos (Kereˇset al. 2005; Dekel & Birnboim 2006) A major step forward was brought by the era of large galaxy or gravitational gas heating (Naab et al. 2007; Khochfar & Ostriker surveys. Thanks to the unprecedented sample size, one of the most 2008; Johansson et al. 2009). The merging of the most massive blue galaxies, however, is not sufficient to explain the population of most-massive red-sequence galaxies. Dissipationless ‘dry merg- ⋆ E-mail: [email protected] ers’ of gas-poor, red-sequence galaxies is therefore also required, † Dunlap Fellow evolving galaxies along the red-sequence as they increase in mass