DOCSLIB.ORG

Most Lensed Quasars at $ Z> 6$ Are Missed by Current Surveys

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Most Lensed Quasars at $ Z> 6$ Are Missed by Current Surveys Draft version January 3, 2019 Typeset using LATEX twocolumn style in AASTeX61 MOST LENSED QUASARS AT Z > 6 ARE MISSED BY CURRENT SURVEYS Fabio Pacucci1 and Abraham Loeb2 1Yale University, Department of Physics, New Haven, CT 06511, USA 2Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA ABSTRACT The discovery of the first strongly lensed (µ ≈ 50) quasar at z > 6 (J0439+1634) represents a breakthrough in our understanding of the early Universe. We derive the theoretical consequences of the new discovery. We predict that the observed population of z > 6 quasars should contain many sources with magnifications µ . 10 and with image separations below the resolution threshold. Additionally, current selection criteria could have missed a substantial population of lensed z > 6 quasars, due to the contamination of the drop-out photometric bands by lens galaxies. We argue that this predicted population of lensed z > 6 quasars would be misclassified and mixed up with low-z galaxies. We quantify the fraction of undetected quasars as a function of the slope of the bright end of the quasar luminosity function, β. For β . 3:6, we predict that the undetected lensed quasars could reach half of the population, whereas for β & 4:5 the vast majority of the z > 6 quasar population is lensed and still undetected. This would significantly affect the z > 6 quasar luminosity function and inferred black hole mass distributions, with profound implications for the ultraviolet, X-ray, and infrared cosmic backgrounds and the growth of early quasars. Keywords: gravitational lensing: strong | galaxies: active | galaxies: luminosity function, mass function | quasars: supermassive black holes | early universe | dark ages, reionization, first stars arXiv:1810.12302v2 [astro-ph.GA] 2 Jan 2019 Corresponding author: Fabio Pacucci [email protected] 2 Pacucci & Loeb 1. INTRODUCTION 2. THEORETICAL FRAMEWORK The discovery of the first strongly lensed quasar at We employ the formalism developed in Pei(1995) to z > 6 (Fan et al. 2018) marks a breakthrough nearly analytically compute the magnification probability dis- two decades after the first theoretical prediction of their tribution, P (µ), due to cosmologically distributed galax- existence (Wyithe & Loeb 2002). Fan et al.(2018) re- ies. We define µ as the total magnification of a source 0 port the detection of J0439+1634, a z = 6:51 quasar at a redshift zs, due to lenses at redshift z . The prob- whose best-fit model predicts three images and a total ability distribution of magnifications larger than µ is magnification µ = 51:3 ± 1:4. This lensed quasar is the Z 1 first example of this class detected during the reioniza- P (> µ) = P (µ0)dµ0 : (1) tion epoch (Barkana & Loeb 2001; Fan et al. 2006). µ Wyithe & Loeb(2002) suggested the possibility of a Following Pei(1993, 1995), we distinguish between the high fraction (up to ∼ 1=3) of lensed sources among magnification µ, relative to a filled beam in a smooth high-z quasars, due to the large lensing optical depths Universe, and the magnification A, relative to an empty reached at z 6. This fraction of the then-known pop- & beam in a clumpy Universe. Calling A¯ the mean magni- ulation of high-z quasars would have had their observed fication, the two variables are related by µ ≡ A=A¯. We flux magnified by factors µ 10. Thus far, none of the & define the moment function Z(sjzs) as ∼ 150 quasars observed at z & 6 (Ba~nadoset al. 2018) have shown evidence for lensing. Z zs Z 1 As suggested by Fan et al.(2018), this lack of lensed 0 0 Z(sjzs) = dz dAρ(A; z jzs)× sources could be accounted for by a selection bias. The 0 1 (2) selection of z & 6 quasars requires a non-detection (or × (As − 1 − 0:4 ln (10)A + s) : at least a strong drop) in the drop-out band at shorter 0 wavelengths than the Lyman break (912 A).˚ In their The quantity ρ(A; z jzs) is the mean number of lenses in detection paper, Fan et al.(2018) point out that the the range (z0, z0 + dz0) with magnifications in the range presence of a lens galaxy along the line of sight of the (A, A + dA) for a given source at a redshift zs. The lensed quasar injects flux into the drop-out bands. This probability distribution function for µ reads effect is very relevant for partly resolved images, a likely Z +1 −1 occurrence for high-z sources. This can thus constitute a P (µ) = µ ds exp [−2πis ln µ + Z(2πisjzs)] : relevant issue in the selection of z & 6 lensed quasars. As −∞ the drop-out bands also contain transmission windows (3) of the intergalactic medium (IGM), Fan et al.(2018) With some analytical adjustments, this integral can be caution that great care is needed in separating the con- efficiently computed via a fast Fourier transform algo- tinuum of the lens galaxy from the transmission spikes rithm. of the IGM. Assuming that the population of lenses is composed of This new discovery has several key implications. First, galaxies with flat rotation curves modeled as a truncated it suggests the likely existence of a population of more singular isothermal sphere, their surface mass density modestly lensed quasars that are thus far undetected profile can be written as (Fan et al. 2018). Second, if this population of unde- −2 σ2 R tected quasars does exist, it could potentially impact in Σ(R) = v 1 + ; (4) 2GR R a very significant way the luminosity and mass functions T of the earliest populations of supermassive black holes where σv is the line-of-sight velocity dispersion, R is the (BHs). In this regard, Wyithe & Loeb(2002) pointed projected radius, RT is the radius containing half of the out that the inclusion of a magnification bias in the high- projected mass, and G is the gravitational constant. The 2 z quasar surveys could have a major effect on the abun- total mass is finite and equal to MT = πσvRT =G. For 13 dance of massive halos (Mh & 10 M ), for which the such a population of lenses, calling δ(x) the Dirac delta mass function is very steep. function In this Letter we derive the theoretical consequences Z 1 0 0 of the discovery of the first strongly lensed quasar in ρ(A; z jzs) = 2τ(z jzs) dffδ[A − A(f)] : (5) the epoch of reionization (Fan et al. 2018). Throughout 0 the Letter we use the latest values of the cosmological 0 The coefficient τ(z jzs) is the strong lensing optical parameters from the Planck Collaboration et al.(2018). depth between source and lens galaxy at z0 (see Pei 0:5 1995). The factor f is defined as f = l=(acrRT ) , Most Lensed Quasars at z > 6 are Missed by Current Surveys 3 where l is the unperturbed impact parameter, and acr is 0.0 the critical impact parameter for double images. In Eq. 5, A(f) = A+(f) for f > 1=r and A(f) = A+(f)+A−(f) 0.5 for f ≤ 1=r, with P(µ > 2, zs > 6) = 0. 20 1.0 2 1 f ± fr + 2 ) A±(f) = ± 1 ; (6) µ 2 f[(f ± r)2 + 4]1=2 > P(µ > 2, z > 6) = 0. 04 ( 1.5 s P g o 1=2 L RT cH0 2.0 Observed frequency of r = 2 0 : (7) lensed z > 6 quasars 4πσvD(zs; z ) P( > µ): β = 3. 6 0 2.5 Here, D(zs; z ) is the angular diameter distance between P( > µ): β = 2. 8 0 source and lens at z , and c is the speed of light. The size J0439 + 1634 : zs = 6. 51, µ = 51. 3 1. 4 −1=2 ± parameter r has dimensions of length and is usually 3.0 0.0 0.5 1.0 1.5 2.0 expressed as a function of the dimensionless parameter Log µ 2 0 F = 3ΩG=[2r D(zs; z )], with ΩG the density parameter of galaxies. Following Pei(1995), we assume F ∼ 0:05 Figure 1. The probability distribution function P (> µ, zs = and we check that our results are unchanged throughout 6:51) is shown for β = 2:8 and β = 3:6, and for magnification the range 0:01 < F < 0:1, which covers the full domain values between µ = 1 and 100. The dashed vertical line indi- cates the magnification factor for the lensed quasar reported of interest. by Fan et al.(2018), with the 1 σ uncertainty level shown as a shaded region. Note that P (µ > 50) = Pobs for β ≈ 3:2. 2.1. Distribution of lens galaxies The theoretical framework described thus far to make range includes the population of lens galaxies that con- predictions for the lensing probability P (> µ) has to be tribute the most to the lensing optical depth. We model supplemented with a realistic cosmological distribution the redshift evolution of the stellar velocity dispersion of foreground (z 6) galaxies, assumed to be early type γ . as σv(z) / (1 + z) . Following Beifiori et al.(2014), we (E/S0) and distributed uniformly in space. The ultra- use the value γ = 0:18 ± 0:06, indicating a mild evolu- violet (UV) luminosity function for galaxies is modeled tion. This value is consistent with other studies (e.g., as a simple Schechter function (Schechter 1976): Mason et al. 2015), but smaller than what found by van αg de Sande et al.(2013). As discussed in Mason et al. Φ? L L Φ(L) = exp − ; (8) (2015), measurements of velocity dispersions at z & 0:5 L? L? L? are very difficult, and large uncertainties in lens models result from a lack of knowledge of how the dark matter where L? is the break luminosity, Φ? is the number den- contained in galaxies (traced by σv) evolves with red- sity of galaxies of luminosity L?, and αg is the slope of the faint end.
Load more

Recommended publications
  • Hubble Finds Clues to the Birth of Supermassive Black Holes 24 May 2016
    Hubble finds clues to the birth of supermassive black holes 24 May 2016 Space Telescope to find and identify the two objects. Both of these newly discovered black hole seed candidates are seen less than a billion years after the Big Bang and have an initial mass of about 100 000 times the Sun. "Our discovery, if confirmed, would explain how these monster black holes were born," said Fabio Pacucci, lead author of the study, of Scuola Normale Superiore in Pisa, Italy. This new result helps to explain why we see supermassive black holes less than one billion years after the Big Bang. This artist's impression shows a possible seed for the formation of a supermassive black hole. Two of these possible seeds were discovered by an Italian team, using three space telescopes: the NASA Chandra X-ray Observatory, the NASA/ESA Hubble Space Telescope, and the NASA Spitzer Space Telescope. Credit: NASA/CXC/M. Weiss Astrophysicists have taken a major step forward in understanding how supermassive black holes formed. Using data from Hubble and two other space telescopes, Italian researchers have found the best evidence yet for the seeds that ultimately grow into these cosmic giants. For years astronomers have debated how the earliest generation of supermassive black holes formed very quickly, relatively speaking, after the Big Bang. Now, an Italian team has identified two objects in the early Universe that seem to be the origin of these early supermassive black holes. This image shows one of two detected supermassive The two objects represent the most promising black hole seeds, OBJ29323, as it is seen by the black hole seed candidates found so far.
    [Show full text]
  • Separating Accretion and Mergers in the Cosmic Growth of Black Holes with X-Ray and Gravitational Wave Observations
    Draft version May 4, 2020 Typeset using LATEX twocolumn style in AASTeX61 SEPARATING ACCRETION AND MERGERS IN THE COSMIC GROWTH OF BLACK HOLES WITH X-RAY AND GRAVITATIONAL WAVE OBSERVATIONS Fabio Pacucci1, 2 and Abraham Loeb1, 2 1Black Hole Initiative, Harvard University, Cambridge, MA 02138, USA 2Center for Astrophysics j Harvard & Smithsonian, Cambridge, MA 02138, USA ABSTRACT Black holes across a broad range of masses play a key role in the evolution of galaxies. The initial seeds of black holes formed at z ∼ 30 and grew over cosmic time by gas accretion and mergers. Using observational data for quasars and theoretical models for the hierarchical assembly of dark matter halos, we study the relative importance of gas accretion and mergers for black hole growth, as a function of redshift (0 < z < 10) and black hole mass 3 10 (10 M < M• < 10 M ). We find that (i) growth by accretion is dominant in a large fraction of the parameter 8 5 space, especially at M• > 10 M and z > 6; and (ii) growth by mergers is dominant at M• < 10 M and z > 5:5, 8 and at M• > 10 M and z < 2. As the growth channel has direct implications for the black hole spin (with gas accretion leading to higher spin values), we test our model against ∼ 20 robust spin measurements available thus far. As expected, the spin tends to decline toward the merger-dominated regime, thereby supporting our model. The next generation of X-ray and gravitational-wave observatories (e.g. Lynx, AXIS, Athena and LISA) will map out populations of black holes up to very high redshift (z ∼ 20), covering the parameter space investigated here in almost its entirety.
    [Show full text]
  • Delphi ODIN the Team in Groningen
    Early galaxy formation and its implications for dark matter, 21cm cosmology and multi-messenger astronomy Pratika Dayal DELPHi ODIN The team in Groningen Ruslan Brilenkov Maxime Trebitsch Anne Hutter Pratika Dayal Laurent Legrand Jonas Bremer Olmo Piana Key collaborators and collaborations Rychard Bouwens: Leiden University, The Netherlands Volker Bromm: University of Texas at Austin, USA Marco Castellano: Observatory of Rome, Italy Benedetta Ciardi: Max Planck Institute for Astrophysics, Germany Tirthankar Choudhury: National Centre for Radio Astronomy, India James Dunlop: Institute for Astronomy, U.K. Andrea Ferrara: Scuola Normale Superiore, Italy Stefan Gottloeber: Leibniz institute for Astrophysics, Germany Hiroyuki Hirashita: ASIAA, Taiwan Umberto Maio: Leibniz institute for Astrophysics, Germany Antonella Maselli: University of Barcelona, Spain Andrei Mesinger: Scuola Normale Superiore, Italy LISA Volker Mueller: Leibniz institute for Astrophysics, Germany Noam Libeskind: Leibniz institute for Astrophysics, Germany Fabio Pacucci: Harvard, USA Laura Pentericci: Observatory of Rome, Italy Elena Rossi: Leiden University, The Netherlands Catherine Trott: ICRAR, Perth, Australia Livia Vallini: Nordita, Stockholm, Sweden Marta Volonteri: Observatory of Paris, France Gustavo Yepes: Universita Autonoma di Madid, Spain… EUCLID HST The outstanding challenges • Hints on the (warm) nature of dark matter using early galaxies • Hints on (warm) nature of dark matter using 21cm data • Early galaxies and GW events from LISA Hints on the (warm) nature of dark matter using early galaxies and 21cm data Hierarchical structure formation in CDM z = 20 z = 10 z =7 z =6 CDM Mass roughly ~100 GeV Lighter the WDM particle, more is the suppression of small scale structure z = 20 z = 10 z =7 z =6 3keV Lighter the WDM particle, more is the suppression of small scale structure z = 20 z = 10 z =7 z =6 1.5keV Since the merger tree starts building up later in WDM models.
    [Show full text]
  • Detecting the Birth of Supermassive Black Holes Formed from Heavy
    A White Paper for the Astro2020 Decadal Survey Detecting the Birth of Supermassive Black Holes Formed from Heavy Seeds Thematic Area: Galaxy Evolution, Multi-Messenger Astronomy and Astrophysics, Formation and Evolution of Compact Objects, Cosmology and Fundamental Physics Principal Author: Name: Fabio Pacucci Institution: Kapteyn Astronomical Institute, Yale University Email: [email protected] Phone: (203)298-2478 Co-authors: Vivienne Baldassare1, Nico Cappelluti2, Xiaohui Fan3, Andrea Ferrara4, Zoltan Haiman5, Priyamvada Natarajan1, Feryal Ozel3, Raffaella Schneider6, Grant R. Tremblay7, Megan C. Urry1, Rosa Valiante8, Alexey Vikhlinin7, Marta Volonteri9 1Yale University, 2University of Miami, 3University of Arizona, 4Scuola Normale Superiore, 5Columbia University, 6Sapienza Universita` di Roma, 7Center for Astrophysics j Harvard & Smithsonian, 8INAF - Roma, 9Institut d’Astrophysique de Paris Artistic representation of a heavy black hole seed, formed in the early Universe. Despite numerous theoretical and observational efforts to observe the birth of the first population of black holes, thus far we are still lacking a confirmed detection. The formation of these objects would be among the most spectacular events in the history of the Universe. (Credit: NASA/CXC/M. Weiss) Introduction The dawn of the first black holes (and stars) occurred ∼ 100 Myr after the Big Bang (Barkana and Loeb 2001). It is very remarkable that numerous observations in the past two decades have shown 9−10 the presence of Super-Massive Black Holes (SMBHs, with masses 10 M ) less than 700 Myr later (e.g., Fan et al. 2006; Mortlock et al. 2011; Wu et al. 2015; Banados˜ et al. 2018). A “seed” is the original black hole that, growing via gas accretion and mergers, generates a SMBH.
    [Show full text]
  • C. Megan Urry
    C. Megan Urry Israel Munson Professor, Department of Physics phone: 203-432-5997 Yale University fax: 203-432-3824 P.O. Box 208120 [email protected] New Haven, CT 06520-8120 urrylab.yale.edu RESEARCH INTERESTS: Evolution of black holes and galaxies, multiwavelength surveys, black hole accretion, jets, unification of active galactic nuclei, blazars KEY SCIENCE ACHIEVEMENTS: • Unification of radio-loud AGN, one of the most highly cited review papers in astronomy and astrophysics. • Established blazars as aligned, beamed, relativistic jets, used variability and SED analysis to probe the physics of relativistic jets and the demographics of blazars. • Developed formalism for impact of relativistic beaming on luminosity functions, established radio galaxies as parent population of blazars. • Quantified black hole growth over past 12 billion years, established that roughly ¾ of accretion is obscured, based on designing GOODS, Stripe 82X and other multiwavelength surveys. • First to establish AGN host galaxies mostly disk-dominated, thus unlikely to be merger-triggered. About 15% merger-triggered locally, rises to ~40% at z~1. EDUCATION Johns Hopkins University Ph.D., Physics, 1984, M.S., Physics, 1979 Tufts University B.S., Physics & Mathematics, 1977 summa cum laude PROFESSIONAL POSITIONS HELD 2001-present Yale University: Israel Munson Professor of Physics & Astronomy; Director, Yale Center for Astronomy and Astrophysics 2007-2013 Yale University: Chair, Department of Physics 1987-2001 Space Telescope Science Institute: Astronomer and Head,
    [Show full text]
  • Stsci Newsletter: 2014 Volume 031 Issue 01
    National Aeronautics and Space Administration A stunning image of NGC 2174, known as the Monkey Head Nebula, was unveiled in Rome by John Grunsfeld, NASA Associate Administrator for the Science Mission Directorate, and Fabio Favata, Head of ESA’s Science Planning and Community Coordination Office. 2014 VOL 31 ISSUE 01 NEWSLETTER Space Telescope Science Institute HST IV & Looking to the Future Neill Reid, [email protected], Antonella Nota, [email protected], & Pam Jeffries, [email protected] pril 24, 2014, marked the 24th anniversary of the launch of the Hubble Space ATelescope. This year also marks the 37th anniversary of the completion of the pivotal roles in establishing both ESA and the European Organization for Nuclear formal, cooperative memorandum of understanding regarding Hubble’s construc- Research (CERN), the premier multi-national scientific enterprises in post-war tion and operation—signed in October 1977 between NASA and the European Europe. Roger Davies (Oxford) co-chaired the Science Organizing Committee, Space Agency (ESA). Throughout those years ESA has played a crucial role in composed of astronomers from Europe and the U.S. For additional information promoting Hubble’s mission, providing technical expertise, instrumentation, and on the conference and final electronic records, see: http://www.stsci.edu/ support scientists. Just as significantly, the ESA research community has made institute/conference/hst4. extensive use of Hubble’s extraordinary capabilities, winning more than 22% of Hubble observations span almost every discipline within astronomy, and that the observing time allocated over the past 24 years and accounting for 27% of the versatility was reflected in the widely varied science program at the conference.
    [Show full text]
  • University of Groningen Detecting the Birth of Supermassive Black Holes
    University of Groningen Detecting the Birth of Supermassive Black Holes Formed from Heavy Seeds Pacucci, Fabio; Baldassare, Vivienne; Cappelluti, Nico; Fan, Xiaohui; Ferrara, Andrea; Haiman, Zoltan; Natarajan, Priyamvada; Ozel, Feryal; Schneider, Raffaella; Tremblay, Grant R. Published in: Bulletin of the American Astronomical Society IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite from it. Please check the document version below. Document Version Final author's version (accepted by publisher, after peer review) Publication date: 2019 Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Pacucci, F., Baldassare, V., Cappelluti, N., Fan, X., Ferrara, A., Haiman, Z., Natarajan, P., Ozel, F., Schneider, R., Tremblay, G. R., Urry, M. C., Valiante, R., Vikhlinin, A., & Volonteri, M. (2019). Detecting the Birth of Supermassive Black Holes Formed from Heavy Seeds. Bulletin of the American Astronomical Society, 51(3), [id. 117 (2019)]. https://ui.adsabs.harvard.edu/abs/2019BAAS...51c.117P Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons). The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license. More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne- amendment. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
    [Show full text]
  • Detecting the Birth of Supermassive Black Holes Formed from Heavy
    A White Paper for the Astro2020 Decadal Survey Detecting the Birth of Supermassive Black Holes Formed from Heavy Seeds Thematic Area: Galaxy Evolution, Multi-Messenger Astronomy and Astrophysics, Formation and Evolution of Compact Objects, Cosmology and Fundamental Physics Principal Author: Name: Fabio Pacucci Institution: Kapteyn Astronomical Institute, Yale University Email: [email protected] Phone: (203)298-2478 Co-authors: Vivienne Baldassare1, Nico Cappelluti2, Xiaohui Fan3, Andrea Ferrara4, Zoltan Haiman5, Priyamvada Natarajan1, Feryal Ozel3, Raffaella Schneider6, Grant R. Tremblay7, Megan C. Urry1, Rosa Valiante8, Alexey Vikhlinin7, Marta Volonteri9 1Yale University, 2University of Miami, 3University of Arizona, 4Scuola Normale Superiore, 5Columbia University, 6Sapienza Universita` di Roma, 7Center for Astrophysics j Harvard & Smithsonian, 8INAF - Roma, 9Institut d’Astrophysique de Paris arXiv:1903.07623v1 [astro-ph.GA] 18 Mar 2019 Artistic representation of a heavy black hole seed, formed in the early Universe. Despite numerous theoretical and observational efforts to observe the birth of the first population of black holes, thus far we are still lacking a confirmed detection. The formation of these objects would be among the most spectacular events in the history of the Universe. (Credit: NASA/CXC/M. Weiss) Introduction The dawn of the first black holes (and stars) occurred ∼ 100 Myr after the Big Bang (Barkana and Loeb 2001). It is very remarkable that numerous observations in the past two decades have shown 9−10 the presence of Super-Massive Black Holes (SMBHs, with masses 10 M ) less than 700 Myr later (e.g., Fan et al. 2006; Mortlock et al. 2011; Wu et al. 2015; Banados˜ et al.
    [Show full text]
  • University of Groningen Detecting the Birth of Supermassive
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by University of Groningen University of Groningen Detecting the Birth of Supermassive Black Holes Formed from Heavy Seeds Pacucci, Fabio; Baldassare, Vivienne; Cappelluti, Nico; Fan, Xiaohui; Ferrara, Andrea; Haiman, Zoltan; Natarajan, Priyamvada; Ozel, Feryal; Schneider, Raffaella; Tremblay, Grant R. Published in: Bulletin of the American Astronomical Society IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite from it. Please check the document version below. Document Version Final author's version (accepted by publisher, after peer review) Publication date: 2019 Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Pacucci, F., Baldassare, V., Cappelluti, N., Fan, X., Ferrara, A., Haiman, Z., ... Volonteri, M. (2019). Detecting the Birth of Supermassive Black Holes Formed from Heavy Seeds. Bulletin of the American Astronomical Society, 51(3), [id. 117 (2019)]. Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons). Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum.
    [Show full text]
  • Alpha Centauri at a Crossroads by Tom Ayres Contents
    Chandra News Chandra News Issue 24 Spring 2017 Alpha Centauri at a Crossroads by Tom Ayres Contents Alpha Centauri at a Crossroads ��� � � � � � � � � � � � 1 Director’s Log � � � � � � � � � � � � � � � � � 8 Project Scientist’s Report � � � � � � � � � � � � � � 10 Program Manager’s Report ��� � � � � � � � � � � � � 11 Chandra Source Catalog ��� � � � � � � � � � � � � � 12 Authentic Data Inquiry a Focus in STEM Programs � � � � � � � 12 HiPS: the Future of Chandra Data Visualization � � � � � � � � 14 Recent Updates to Chandra Calibration � � � � � � � � � � 15 Michael Juda (1959–2016) � � � � � � � � � � � � � 16 ACIS Update � � � � � � � � � � � � � � � � � 18 Martin Zombeck (1936–2016) � � � � � � � � � � � � 19 HRC Update � � � � � � � � � � � � � � � � � 20 HETG Update � � � � � � � � � � � � � � � � � 21 LETG Update ��� � � � � � � � � � � � � � � � � 26 CIAO 4.9 and Beyond � � � � � � � � � � � � � � � 29 The Results of the Cycle 18 Peer Review � � � � � � � � � � 32 Einstein Fellowship Program � � � � � � � � � � � � � 36 2016 Press Releases � � � � � � � � � � � � � � � 37 An August Week: Chandra Science for the Next Decade � � � � � � 38 The Chandra Newsletter appears once a year and is edited by Rodolfo Montez Jr., with editorial assistance and layout by Tara Gokas. We welcome contributions from readers. Comments on the newsletter, or corrections and additions to the hardcopy mailing list should be sent to: [email protected]. Follow the Chandra Director's Office on Facebook, Google+ and Twitter (@ChandraCDO). Spring 2017 1 Alpha Centauri at a Crossroads The two larger stars, Alpha Cen A and B, are in a relative- ly tight 80-year orbit, about the size of the outer Solar Sys- Tom Ayres tem. Tiny C, not much bigger than Jupiter, revolves around Center for Astrophysics and Space Astronomy the central pair at a great distance, a few hundred times that University of Colorado of Pluto from the Sun, taking perhaps half a million years Boulder, Colorado to make a full circuit.
    [Show full text]
  • Dear Harvard Students, the Harvard
    Dear Harvard Students, The Harvard-Smithsonian Center for Astrophysics (CfA, http://www.cfa.harvard.edu/), located at 60 Garden Street opposite the Quadrangle, is one of the world’s great centers for research in astrophysics, with over 300 scientists and access to powerful astronomical observatories worldwide and in space. The following is a partial list of CfA research opportunities for undergraduates. I encourage students to contact these scientists directly to inquire about these opportunities. In addition, you should feel free to reach out to any SAO scientist and faculty (some of which are listed here: https:// astronomy.fas.harvard.edu/book/astrophysics-advisors) and inquire if they or someone in their group are interested in advising you — not all prospective undergraduate research advisors put down a project in this document. In addition to a project description, some of the research advisors have indicated within which framework (e.g. senior thesis, paid semester work, summer research internship) that their research project can be carried out, as well as recommended prerequisites. I want to make two comments on this. First, if you identify a research project that you would like to pursue as a paid position during the semester, but the advisor does not have resources to support this financially, please reach out to me. We have some limited departmental resources set apart for students eligible for work-study as well as those with commensurate financial need (regardless of citizenship) who want to do astronomy research. For the summer there are many opportunities to apply for your own funding to carry out a research project (https://astronomy.fas.harvard.edu/research-opportunities- undergraduates).
    [Show full text]
  • Electromagnetic Window Into the Dawn of Black Holes
    Electromagnetic Window into the Dawn of Black Holes A White Paper for the 2020 Decadal Survey ematic Areas: ◻ Planetary Systems ◻ Star and Planet formation ◻" Formation and evolution of compact objects ◻" Cosmology and Fundamental Physics ◻ Stars and Stellar Evolution ◻ Resolved stellar populations and their environments ◻" Galaxy Evolution ◻" Multi-Messenger Astronomy and Astrophysics Authors: Zoltan´ Haiman (Columbia University), William N. Brandt (Pennsylvania State University), Alexey Vikhlinin (Harvard-Smithsonian Center for Astrophysics), Jillian Bellovary (Queensborough Community College/AMNH), Elena Gallo (University of Michigan), Jenny Greene (Princeton Univer- sity), Kohei Inayoshi (Peking University), Joseph Lazio (JPL), Bret Lehmer (University of Arkansas), Bin Luo (Nanjing University), Piero Madau (UC Santa Cruz), Priya Natarajan (Yale University), Feryal Ozel¨ (University of Arizona), Fabio Pacucci (Kapteyn Astronomical Institute), Alberto Sesana (University of Birmingham), Daniel Stern (JPL), Christian Vignali (University of Bologna), Eli Visbal (Flatiron Institue), Fabio Vito (Pontif´ıcia Universidad Catolica´ de Chile), Marta Volonteri (Institut d’Astrophysique de Paris), Joan Wrobel (NRAO) Endorsers: Emanuele Berti (Johns Hopkins University), Volker Bromm (University of Texas), Greg Bryan (Columbia University), Nico Cappelluti (University of Miami), Anastasia Fialkov (University of Sussex), Martin Haehnelt (Cambridge University), John Regan (Dublin City University), Angelo Ricarte (Yale University), John Wise (Georgia Institute of Technology), Jemma Wolcott- Green (Columbia University) Contact: Zoltan´ Haiman Address: Department of Astronomy Mail Code 5246, Columbia University New York, NY 10027, USA Email: [email protected] Phone: (212) 854-6822 1 6 10 Executive Summary. Massive black holes, MBH = 10 − 10 M⊙, are known to reside in local galactic nuclei. Observations over the past 20 years have revealed that these black holes are common by the time the Universe is several Gyr old.
    [Show full text]