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A. M. J. Mortier

Other affiliations: University of Edinburgh
Bio: A. M. J. Mortier is an academic researcher from Imperial College London. The author has contributed to research in topics: Galaxy & Redshift. The author has an hindex of 11, co-authored 12 publications receiving 2567 citations. Previous affiliations of A. M. J. Mortier include University of Edinburgh.

Papers
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Journal ArticleDOI
Seb Oliver1, James J. Bock2, James J. Bock3, Bruno Altieri4, Alexandre Amblard5, V. Arumugam6, Herve Aussel7, Tom Babbedge8, Alexandre Beelen9, Matthieu Béthermin7, Matthieu Béthermin9, Andrew Blain2, Alessandro Boselli10, C. Bridge2, Drew Brisbin11, V. Buat10, Denis Burgarella10, N. Castro-Rodríguez12, N. Castro-Rodríguez13, Antonio Cava14, P. Chanial7, Michele Cirasuolo15, David L. Clements8, A. Conley16, L. Conversi4, Asantha Cooray17, Asantha Cooray2, C. D. Dowell2, C. D. Dowell3, Elizabeth Dubois1, Eli Dwek18, Simon Dye19, Stephen Anthony Eales20, David Elbaz7, Duncan Farrah1, A. Feltre21, P. Ferrero13, P. Ferrero12, N. Fiolet22, N. Fiolet9, M. Fox8, Alberto Franceschini21, Walter Kieran Gear20, E. Giovannoli10, Jason Glenn16, Yan Gong17, E. A. González Solares23, Matthew Joseph Griffin20, Mark Halpern24, Martin Harwit, Evanthia Hatziminaoglou, Sebastien Heinis10, Peter Hurley1, Ho Seong Hwang7, A. Hyde8, Edo Ibar15, O. Ilbert10, K. G. Isaak25, Rob Ivison15, Rob Ivison6, Guilaine Lagache9, E. Le Floc'h7, L. R. Levenson2, L. R. Levenson3, B. Lo Faro21, Nanyao Y. Lu2, S. C. Madden7, Bruno Maffei26, Georgios E. Magdis7, G. Mainetti21, Lucia Marchetti21, G. Marsden24, J. Marshall3, J. Marshall2, A. M. J. Mortier8, Hien Nguyen2, Hien Nguyen3, B. O'Halloran8, Alain Omont22, Mat Page27, P. Panuzzo7, Andreas Papageorgiou20, H. Patel8, Chris Pearson28, Chris Pearson29, Ismael Perez-Fournon12, Ismael Perez-Fournon13, Michael Pohlen20, Jonathan Rawlings27, Gwenifer Raymond20, Dimitra Rigopoulou28, Dimitra Rigopoulou30, L. Riguccini7, D. Rizzo8, Giulia Rodighiero21, Isaac Roseboom1, Isaac Roseboom6, Michael Rowan-Robinson8, M. Sanchez Portal4, Benjamin L. Schulz2, Douglas Scott24, Nick Seymour31, Nick Seymour27, D. L. Shupe2, A. J. Smith1, Jamie Stevens32, M. Symeonidis27, Markos Trichas33, K. E. Tugwell27, Mattia Vaccari21, Ivan Valtchanov4, Joaquin Vieira2, Marco P. Viero2, L. Vigroux22, Lifan Wang1, Robyn L. Ward1, Julie Wardlow17, G. Wright15, C. K. Xu2, Michael Zemcov3, Michael Zemcov2 
TL;DR: The Herschel Multi-tiered Extragalactic Survey (HerMES) is a legacy program designed to map a set of nested fields totalling ∼380deg^2 as mentioned in this paper.
Abstract: The Herschel Multi-tiered Extragalactic Survey (HerMES) is a legacy programme designed to map a set of nested fields totalling ∼380 deg^2. Fields range in size from 0.01 to ∼20 deg^2, using the Herschel-Spectral and Photometric Imaging Receiver (SPIRE) (at 250, 350 and 500 μm) and the Herschel-Photodetector Array Camera and Spectrometer (PACS) (at 100 and 160 μm), with an additional wider component of 270 deg^2 with SPIRE alone. These bands cover the peak of the redshifted thermal spectral energy distribution from interstellar dust and thus capture the reprocessed optical and ultraviolet radiation from star formation that has been absorbed by dust, and are critical for forming a complete multiwavelength understanding of galaxy formation and evolution. The survey will detect of the order of 100 000 galaxies at 5σ in some of the best-studied fields in the sky. Additionally, HerMES is closely coordinated with the PACS Evolutionary Probe survey. Making maximum use of the full spectrum of ancillary data, from radio to X-ray wavelengths, it is designed to facilitate redshift determination, rapidly identify unusual objects and understand the relationships between thermal emission from dust and other processes. Scientific questions HerMES will be used to answer include the total infrared emission of galaxies, the evolution of the luminosity function, the clustering properties of dusty galaxies and the properties of populations of galaxies which lie below the confusion limit through lensing and statistical techniques. This paper defines the survey observations and data products, outlines the primary scientific goals of the HerMES team, and reviews some of the early results.

852 citations

Journal ArticleDOI
Seb Oliver1, James J. Bock2, James J. Bock3, Bruno Altieri4, Alexandre Amblard5, V. Arumugam6, Herve Aussel7, Tom Babbedge8, Alexandre Beelen, Matthieu Béthermin7, Andrew Blain3, Alessandro Boselli9, C. Bridge3, Drew Brisbin10, V. Buat9, Denis Burgarella9, N. Castro-Rodríguez11, N. Castro-Rodríguez12, Antonio Cava13, P. Chanial7, Michele Cirasuolo14, David L. Clements8, A. Conley15, L. Conversi4, Asantha Cooray16, Asantha Cooray3, C. D. Dowell3, C. D. Dowell2, Elizabeth Dubois1, Eli Dwek17, Simon Dye18, Stephen Anthony Eales19, David Elbaz7, Duncan Farrah1, A. Feltre20, P. Ferrero12, P. Ferrero11, N. Fiolet21, M. Fox8, Alberto Franceschini20, Walter Kieran Gear19, E. Giovannoli9, Jason Glenn15, Yan Gong16, E. A. González Solares22, Matthew Joseph Griffin19, Mark Halpern23, Martin Harwit, Evanthia Hatziminaoglou, Sebastien Heinis9, Peter Hurley1, Ho Seong Hwang7, A. Hyde8, Edo Ibar14, O. Ilbert9, K. G. Isaak24, Rob Ivison6, Rob Ivison14, Guilaine Lagache, E. Le Floc'h7, L. R. Levenson3, L. R. Levenson2, B. Lo Faro20, Nanyao Y. Lu3, S. C. Madden7, Bruno Maffei25, Georgios E. Magdis7, G. Mainetti20, Lucia Marchetti20, G. Marsden23, J. Marshall2, J. Marshall3, A. M. J. Mortier8, Hien Nguyen3, Hien Nguyen2, B. O'Halloran8, Alain Omont21, Mat Page26, P. Panuzzo7, Andreas Papageorgiou19, H. Patel8, Chris Pearson27, Chris Pearson28, Ismael Perez-Fournon11, Ismael Perez-Fournon12, Michael Pohlen19, Jonathan Rawlings26, Gwenifer Raymond19, Dimitra Rigopoulou29, Dimitra Rigopoulou27, L. Riguccini7, D. Rizzo8, Giulia Rodighiero20, Isaac Roseboom1, Isaac Roseboom6, Michael Rowan-Robinson8, M. Sanchez Portal4, Benjamin L. Schulz3, Douglas Scott23, Nick Seymour26, Nick Seymour30, D. L. Shupe3, A. J. Smith1, Jamie Stevens31, M. Symeonidis26, Markos Trichas32, K. E. Tugwell26, Mattia Vaccari20, Ivan Valtchanov4, Joaquin Vieira3, Marco P. Viero3, L. Vigroux21, Lifan Wang1, Robyn L. Ward1, Julie Wardlow16, G. Wright14, C. K. Xu3, Michael Zemcov2, Michael Zemcov3 
TL;DR: The Herschel Multi-tiered Extragalactic Survey (HerMES) is a legacy program designed to map a set of nested fields totalling ~380 deg^2 as mentioned in this paper.
Abstract: The Herschel Multi-tiered Extragalactic Survey, HerMES, is a legacy program designed to map a set of nested fields totalling ~380 deg^2. Fields range in size from 0.01 to ~20 deg^2, using Herschel-SPIRE (at 250, 350 and 500 \mu m), and Herschel-PACS (at 100 and 160 \mu m), with an additional wider component of 270 deg^2 with SPIRE alone. These bands cover the peak of the redshifted thermal spectral energy distribution from interstellar dust and thus capture the re-processed optical and ultra-violet radiation from star formation that has been absorbed by dust, and are critical for forming a complete multi-wavelength understanding of galaxy formation and evolution. The survey will detect of order 100,000 galaxies at 5\sigma in some of the best studied fields in the sky. Additionally, HerMES is closely coordinated with the PACS Evolutionary Probe survey. Making maximum use of the full spectrum of ancillary data, from radio to X-ray wavelengths, it is designed to: facilitate redshift determination; rapidly identify unusual objects; and understand the relationships between thermal emission from dust and other processes. Scientific questions HerMES will be used to answer include: the total infrared emission of galaxies; the evolution of the luminosity function; the clustering properties of dusty galaxies; and the properties of populations of galaxies which lie below the confusion limit through lensing and statistical techniques. This paper defines the survey observations and data products, outlines the primary scientific goals of the HerMES team, and reviews some of the early results.

707 citations

Journal ArticleDOI
D. Elbaz1, Ho Seong Hwang1, Benjamin Magnelli2, Emanuele Daddi1, Herve Aussel1, Bruno Altieri3, Alexandre Amblard4, Paola Andreani5, V. Arumugam6, Robbie Richard Auld7, Tom Babbedge8, S. Berta2, Andrew Blain9, James J. Bock10, James J. Bock9, Ángel Bongiovanni11, Alessandro Boselli12, V. Buat12, Denis Burgarella12, N. Castro-Rodriguez11, Antonio Cava11, J. Cepa11, Pierre Chanial8, Ranga-Ram Chary9, Andrea Cimatti13, David L. Clements8, A. Conley14, L. Conversi3, Asantha Cooray4, Asantha Cooray9, Mark Dickinson, H. Dominguez5, Charles D. Dowell9, Charles D. Dowell10, James Dunlop6, Eli Dwek15, Stephen Anthony Eales7, Duncan Farrah16, N. M. Förster Schreiber2, M. Fox8, Alberto Franceschini17, Walter Kieran Gear7, Reinhard Genzel2, Jason Glenn14, Matthew Joseph Griffin7, Carlotta Gruppioni5, Mark Halpern18, Evanthia Hatziminaoglou, Edo Ibar19, Kate Gudrun Isaak7, Rob Ivison19, Rob Ivison6, Guilaine Lagache20, D. Le Borgne21, E. Le Floc'h1, L. R. Levenson10, L. R. Levenson9, Nanyao Y. Lu9, Dieter Lutz2, Suzanne C. Madden1, Bruno Maffei22, Georgios E. Magdis1, G. Mainetti17, Roberto Maiolino5, Lucia Marchetti17, A. M. J. Mortier8, Hien Nguyen10, Hien Nguyen9, Raanan Nordon2, B. O'Halloran8, K. Okumura1, Seb Oliver16, Alain Omont21, M. J. Page23, P. Panuzzo1, Andreas Papageorgiou7, Chris Pearson24, Chris Pearson25, I. Perez Fournon11, A. M. Pérez García11, Albrecht Poglitsch2, Michael Pohlen7, P. Popesso2, Francesca Pozzi5, Jonathan Rawlings23, Dimitra Rigopoulou24, Dimitra Rigopoulou26, L. Riguccini1, D. Rizzo8, Giulia Rodighiero17, Isaac Roseboom16, Michael Rowan-Robinson8, Amélie Saintonge2, M. Sanchez Portal3, P. Santini5, Marc Sauvage1, Benjamin L. Schulz9, Douglas Scott18, Nick Seymour23, Lijing Shao2, D. L. Shupe9, A. J. Smith16, Jamie Stevens27, E. Sturm2, M. Symeonidis23, Linda J. Tacconi2, Markos Trichas8, K. E. Tugwell23, Mattia Vaccari17, Ivan Valtchanov3, Joaquin Vieira9, L. Vigroux21, Lifan Wang16, Robyn L. Ward16, G. Wright19, C. K. Xu9, Michael Zemcov10, Michael Zemcov9 
TL;DR: In this paper, the spectral energy distribution and dust temperature of galaxies have strongly evolved over the last 80% of the age of the Universe, and possible consequences for the determination of star-formation rates (SFR) and any evidence for a major change in their starformation properties.
Abstract: The Herschel Space Observatory enables us to accurately measure the bolometric output of starburst galaxies and active galactic nuclei (AGN) by directly sampling the peak of their far-infrared (IR) emission. Here we examine whether the spectral energy distribution (SED) and dust temperature of galaxies have strongly evolved over the last 80% of the age of the Universe. We discuss possible consequences for the determination of star-formation rates (SFR) and any evidence for a major change in their star-formation properties. We use Herschel deep extragalactic surveys from 100 to 500 μm to compute total IR luminosities in galaxies down to the faintest levels, using PACS and SPIRE in the GOODS-North field (PEP and HerMES key programs). An extension to fainter luminosities is done by stacking images on 24 μm prior positions. We show that measurements in the SPIRE bands can be used below the statistical confusion limit if information at higher spatial resolution is used, e.g. at 24 μm, to identify “isolated” galaxies whose flux is not boosted by bright neighbors. Below z ~ 1.5, mid-IR extrapolations are correct for star-forming galaxies with a dispersion of only 40% (0.15 dex), therefore similar to z ~ 0 galaxies, over three decades in luminosity below the regime of ultra-luminous IR galaxies (ULIRGs, LIR ≥ 1012 ). This narrow distribution is puzzling when considering the range of physical processes that could have affected the SED of these galaxies. Extrapolations from only one of the 160 μm, 250 μm or 350 μm bands alone tend to overestimate the total IR luminosity. This may be explained by the lack of far-IR constraints around and above ~150 μm (rest-frame) before Herschel on those templates. We also note that the dust temperature of luminous IR galaxies (LIRGs, LIR ≥ 1011 ) around z ~ 1 is mildly colder by 10–15% than their local analogs and up to 20% for ULIRGs at z ~ 1.6 (using a single modified blackbody-fit to the peak far-IR emission with an emissivity index of β = 1.5). Above z = 1.5, distant galaxies are found to exhibit a substantially larger mid- over far-IR ratio, which could either result from stronger broad emission lines or warm dust continuum heated by a hidden AGN. Two thirds of the AGNs identified in the field with a measured redshift exhibit the same behavior as purely star-forming galaxies. Hence a large fraction of AGNs harbor coeval star formation at very high SFR and in conditions similar to purely star-forming galaxies.

245 citations

Journal ArticleDOI
D. Elbaz, Ho Seong Hwang, Benjamin Magnelli, Emanuele Daddi, H. Aussel, Bruno Altieri, Alexandre Amblard, P. Andreani, V. Arumugam, Robbie Richard Auld, Tom Babbedge, S. Berta, Andrew Blain, James J. Bock, Ángel Bongiovanni, Alessandro Boselli, V. Buat, Denis Burgarella, N. Castro-Rodriguez, Antonio Cava, J. Cepa, P. Chanial, Ranga-Ram Chary, A. Cimatti, David L. Clements, A. Conley, Luca Conversi, Asantha Cooray, Mark Dickinson, H. Dominguez, C. D. Dowell, James Dunlop, E. Dwek, Stephen Anthony Eales, Duncan Farrah, N. M. Förster Schreiber, M. Fox, Alberto Franceschini, Walter Kieran Gear, Reinhard Genzel, Jason Glenn, Matthew Joseph Griffin, Carlotta Gruppioni, Mark Halpern, Evanthia Hatziminaoglou, E. Ibar, K. G. Isaak, Rob Ivison, Guilaine Lagache, D. Le Borgne, E. Le Floc'h, L. R. Levenson, Nanyao Y. Lu, Dieter Lutz, S. C. Madden, Bruno Maffei, Georgios E. Magdis, G. Mainetti, Roberto Maiolino, Lucia Marchetti, A. M. J. Mortier, Hien Nguyen, Raanan Nordon, B. O'Halloran, K. Okumura, Seb Oliver, A. Omont, M. J. Page, P. Panuzzo, Andreas Papageorgiou, Chris Pearson, I. Perez Fournon, A. M. Pérez García, Albrecht Poglitsch, Michael Pohlen, P. Popesso, Francesca Pozzi, Jonathan Rawlings, Dimitra Rigopoulou, L. Riguccini, D. Rizzo, Giulia Rodighiero, Isaac Roseboom, Michael Rowan-Robinson, Amelie Saintonge, M. Sánchez-Portal, P. Santini, Marc Sauvage, Benjamin L. Schulz, Douglas Scott, Nick Seymour, Lijing Shao, D. L. Shupe, A. J. Smith, Jamie Stevens, E. Sturm, M. Symeonidis, Linda J. Tacconi, Markos Trichas, K. E. Tugwell 
TL;DR: In this article, the spectral energy distribution (SED) and dust temperature of galaxies have strongly evolved since z~2.5, which may either result from stronger broad emission lines or warm dust continuum heated by a hidden AGN.
Abstract: The Herschel Space Observatory enables us to accurately measure the bolometric output of starburst galaxies and active galactic nuclei (AGN) by directly sampling the peak of their far-infrared (IR) emission. Here we examine whether the spectral energy distribution (SED) and dust temperature of galaxies have strongly evolved since z~2.5. We use Herschel deep extragalactic surveys from 100 to 500um to compute total IR luminosities in galaxies down to the faintest levels, using PACS and SPIRE in the GOODS-North field (PEP and HerMES key programs). We show that measurements in the SPIRE bands can be used below the statistical confusion limit if information at higher spatial resolution is used to identify isolated galaxies whose flux is not boosted by bright neighbors. Below z~1.5, mid-IR extrapolations are correct for star-forming galaxies with a dispersion of only 40% (0.15dex), therefore similar to z~0 galaxies. This narrow distribution is puzzling when considering the range of physical processes that could have affected the SED of these galaxies. Extrapolations from only one of the 160um, 250um or 350um bands alone tend to overestimate the total IR luminosity. This may be explained by the lack of far-IR constraints around and above ~150um (rest-frame) on local templates. We also note that the dust temperature of luminous IR galaxies around z~1 is mildly colder by 10-15% than their local analogs and up to 20% for ULIRGs at z~1.6. Above z=1.5, distant galaxies are found to exhibit a substantially larger mid- over far-IR ratio, which could either result from stronger broad emission lines or warm dust continuum heated by a hidden AGN. Two thirds of the AGNs identified in the field with a measured redshift exhibit the same behavior as purely star-forming galaxies. Hence a large fraction of AGNs harbor star formation at very high SFR and in conditions similar to purely star-forming galaxies.

229 citations

Journal ArticleDOI
J. C. Mauduit1, Mark Lacy2, Duncan Farrah3, Jason Surace1, Matt J. Jarvis4, S. J. Oliver3, Claudia Maraston5, Mattia Vaccari6, Mattia Vaccari7, Lucia Marchetti7, Gregory R. Zeimann8, E. Gonzales-Solares9, Janine Pforr2, Janine Pforr5, Andreea Petric1, Bruno M. B. Henriques2, Peter A. Thomas2, Jose Afonso10, Alessandro Rettura11, Gillian Wilson11, J. T. Falder4, James E. Geach12, Minh Huynh, Ray P. Norris13, Nick Seymour13, Gordon T. Richards14, S. A. Stanford8, S. A. Stanford15, David M. Alexander16, Robert H. Becker8, Robert H. Becker15, Philip Best, Luca Bizzocchi10, David Bonfield4, N. Castro17, Antonio Cava17, Scott Chapman9, N. Christopher18, David L. Clements19, Giovanni Covone20, Giovanni Covone21, N. Dubois3, James Dunlop, E. Dyke4, Alastair C. Edge16, Henry C. Ferguson22, S. Foucaud23, Alberto Franceschini7, Roy R. Gal24, J. K. Grant25, Marco Grossi10, Evanthia Hatziminaoglou, Samantha Hickey4, Jacqueline Hodge26, J. S. Huang26, Rob Ivison, M. Kim1, O. LeFevre, M. D. Lehnert, Carol J. Lonsdale1, Lori M. Lubin8, Ross J. McLure, Hugo Messias10, A. Martinez-Sansigre5, A. Martinez-Sansigre18, A. M. J. Mortier27, D. M. Nielsen28, Masami Ouchi29, G. Parish4, Ismael Perez-Fournon17, Marguerite Pierre30, Steve Rawlings18, Anthony C. S. Readhead1, S. E. Ridgway, Dimitra Rigopoulou18, A. K. Romer2, I. G. Rosebloom2, Huub Röttgering31, Michael Rowan-Robinson19, Anna Sajina32, Chris Simpson33, Ian Smail16, Gordon K. Squires1, Jamie Stevens4, R. Taylor25, Markos Trichas19, Tanya Urrutia34, E. van Kampen25, Aprajita Verma18, C. K. Xu1 
TL;DR: The Spitzer Extragalactic Representative Volume Survey (SERVS) as discussed by the authors is designed to enable the study of galaxy evolution as a function of environment from z~5 to the present day, and is the first survey both large enough and deep enough to put rare objects such as luminous quasars and galaxy clusters at z>1 into their cosmological context.
Abstract: We present the Spitzer Extragalactic Representative Volume Survey (SERVS), an 18 square degrees medium-deep survey at 3.6 and 4.5 microns with the post-cryogenic Spitzer Space Telescope to ~2 microJy (AB=23.1) depth of five highly observed astronomical fields (ELAIS-N1, ELAIS-S1, Lockman Hole, Chandra Deep Field South and XMM-LSS). SERVS is designed to enable the study of galaxy evolution as a function of environment from z~5 to the present day, and is the first extragalactic survey both large enough and deep enough to put rare objects such as luminous quasars and galaxy clusters at z>1 into their cosmological context. SERVS is designed to overlap with several key surveys at optical, near- through far-infrared, submillimeter and radio wavelengths to provide an unprecedented view of the formation and evolution of massive galaxies. In this paper, we discuss the SERVS survey design, the data processing flow from image reduction and mosaicing to catalogs, as well as coverage of ancillary data from other surveys in the SERVS fields. We also highlight a variety of early science results from the survey.

181 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the authors review the range of complementary techniques and theoretical tools that allow astronomers to map the cosmic history of star formation, heavy element production, and reionization of the Universe from the cosmic "dark ages" to the present epoch.
Abstract: Over the past two decades, an avalanche of data from multiwavelength imaging and spectroscopic surveys has revolutionized our view of galaxy formation and evolution. Here we review the range of complementary techniques and theoretical tools that allow astronomers to map the cosmic history of star formation, heavy element production, and reionization of the Universe from the cosmic "dark ages" to the present epoch. A consistent picture is emerging, whereby the star-formation rate density peaked approximately 3.5 Gyr after the Big Bang, at z~1.9, and declined exponentially at later times, with an e-folding timescale of 3.9 Gyr. Half of the stellar mass observed today was formed before a redshift z = 1.3. About 25% formed before the peak of the cosmic star-formation rate density, and another 25% formed after z = 0.7. Less than ~1% of today's stars formed during the epoch of reionization. Under the assumption of a universal initial mass function, the global stellar mass density inferred at any epoch matches reasonably well the time integral of all the preceding star-formation activity. The comoving rates of star formation and central black hole accretion follow a similar rise and fall, offering evidence for co-evolution of black holes and their host galaxies. The rise of the mean metallicity of the Universe to about 0.001 solar by z = 6, one Gyr after the Big Bang, appears to have been accompanied by the production of fewer than ten hydrogen Lyman-continuum photons per baryon, a rather tight budget for cosmological reionization.

3,104 citations

Journal ArticleDOI
TL;DR: In this paper, the authors review the range of complementary techniques and theoretical tools that allow astronomers to map the cosmic history of star formation, heavy element production, and reionization of the Universe from the cosmic "dark ages" to the present epoch.
Abstract: Over the past two decades, an avalanche of data from multiwavelength imaging and spectroscopic surveys has revolutionized our view of galaxy formation and evolution. Here we review the range of complementary techniques and theoretical tools that allow astronomers to map the cosmic history of star formation, heavy element production, and reionization of the Universe from the cosmic "dark ages" to the present epoch. A consistent picture is emerging, whereby the star-formation rate density peaked approximately 3.5 Gyr after the Big Bang, at z~1.9, and declined exponentially at later times, with an e-folding timescale of 3.9 Gyr. Half of the stellar mass observed today was formed before a redshift z = 1.3. About 25% formed before the peak of the cosmic star-formation rate density, and another 25% formed after z = 0.7. Less than ~1% of today's stars formed during the epoch of reionization. Under the assumption of a universal initial mass function, the global stellar mass density inferred at any epoch matches reasonably well the time integral of all the preceding star-formation activity. The comoving rates of star formation and central black hole accretion follow a similar rise and fall, offering evidence for co-evolution of black holes and their host galaxies. The rise of the mean metallicity of the Universe to about 0.001 solar by z = 6, one Gyr after the Big Bang, appears to have been accompanied by the production of fewer than ten hydrogen Lyman-continuum photons per baryon, a rather tight budget for cosmological reionization.

1,626 citations

Journal ArticleDOI
TL;DR: In this paper, the authors examined the infrared (IR) 3-500μm spectral energy distributions (SEDs) of galaxies at 0 < z < 2.5, supplemented by a local reference sample from IRAS, ISO, Spitzer, and AKARI data.
Abstract: We present the deepest 100 to 500 μm far-infrared observations obtained with the Herschel Space Observatory as part of the GOODS-Herschel key program, and examine the infrared (IR) 3–500 μm spectral energy distributions (SEDs) of galaxies at 0 < z < 2.5, supplemented by a local reference sample from IRAS, ISO, Spitzer, and AKARI data. We determine the projected star formation densities of local galaxies from their radio and mid-IR continuum sizes. We find that the ratio of total IR luminosity to rest-frame 8 μm luminosity, IR8 (≡ L_(IR)^(tot)/L_8), follows a Gaussian distribution centered on IR8 = 4 (σ = 1.6) and defines an IR main sequence for star-forming galaxies independent of redshift and luminosity. Outliers from this main sequence produce a tail skewed toward higher values of IR8. This minority population ( 3 × 10^(10) L_⊙ kpc^(-2)) and a high specific star formation rate (i.e., starbursts). The rest-frame, UV-2700 A size of these distant starbursts is typically half that of main sequence galaxies, supporting the correlation between star formation density and starburst activity that is measured for the local sample. Locally, luminous and ultraluminous IR galaxies, (U)LIRGs (L_(IR)^(tot)≥ 10^(11) L_☉), are systematically in the starburst mode, whereas most distant (U)LIRGs form stars in the “normal” main sequence mode. This confusion between two modes of star formation is the cause of the so-called “mid-IR excess” population of galaxies found at z > 1.5 by previous studies. Main sequence galaxies have strong polycyclic aromatic hydrocarbon (PAH) emission line features, a broad far-IR bump resulting from a combination of dust temperatures (T_(dust) ~ 15–50 K), and an effective T_(dust) ~ 31 K, as derived from the peak wavelength of their infrared SED. Galaxies in the starburst regime instead exhibit weak PAH equivalent widths and a sharper far-IR bump with an effective T_(dust)~ 40 K. Finally, we present evidence that the mid-to-far IR emission of X-ray active galactic nuclei (AGN) is predominantly produced by star formation and that candidate dusty AGNs with a power-law emission in the mid-IR systematically occur in compact, dusty starbursts. After correcting for the effect of starbursts on IR8, we identify new candidates for extremely obscured AGNs.

1,235 citations

Journal ArticleDOI
TL;DR: The COSMOS2015(24) catalog as mentioned in this paper contains precise photometric redshifts and stellar masses for more than half a million objects over the 2deg(2) COSmOS field, which is highly optimized for the study of galaxy evolution and environments in the early universe.
Abstract: We present the COSMOS2015(24) catalog, which contains precise photometric redshifts and stellar masses for more than half a million objects over the 2deg(2) COSMOS field. Including new YJHK(s) images from the UltraVISTA-DR2 survey, Y-band images from Subaru/Hyper-Suprime-Cam, and infrared data from the Spitzer Large Area Survey with the Hyper-Suprime-Cam Spitzer legacy program, this near-infrared-selected catalog is highly optimized for the study of galaxy evolution and environments in the early universe. To maximize catalog completeness for bluer objects and at higher redshifts, objects have been detected on a chi(2) sum of the YJHK(s) and z(++) images. The catalog contains similar to 6 x 10(5) objects in the 1.5 deg(2) UltraVISTA-DR2 region and similar to 1.5 x 10(5) objects are detected in the “ultra-deep stripes” (0.62 deg(2)) at K-s \textless= 24.7 (3 sigma, 3 `', AB magnitude). Through a comparison with the zCOSMOS-bright spectroscopic redshifts, we measure a photometric redshift precision of sigma(Delta z(1) (+ zs)) = 0.007 and a catastrophic failure fraction of eta = 0.5%. At 3 \textless z \textless 6, using the unique database of spectroscopic redshifts in COSMOS, we find sigma(Delta z(1) (+ zs)) = 0.021 and eta = 13.2%. The deepest regions reach a 90% completeness limit of 10(10)M(circle dot) to z = 4. Detailed comparisons of the color distributions, number counts, and clustering show excellent agreement with the literature in the same mass ranges. COSMOS2015 represents a unique, publicly available, valuable resource with which to investigate the evolution of galaxies within their environment back to the earliest stages of the history of the universe. The COSMOS2015 catalog is distributed via anonymous ftp and through the usual astronomical archive systems (CDS, ESO Phase 3, IRSA).

1,002 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used the first systematic data sets of CO molecular line emission in z∼ 1 − 3 normal star-forming galaxies (SFGs) for a comparison of the dependence of galaxy-averaged star formation rates on molecular gas masses at low and high redshifts, and in different galactic environments.
Abstract: We use the first systematic data sets of CO molecular line emission in z∼ 1–3 normal star-forming galaxies (SFGs) for a comparison of the dependence of galaxy-averaged star formation rates on molecular gas masses at low and high redshifts, and in different galactic environments. Although the current high-z samples are still small and biased towards the luminous and massive tail of the actively star-forming ‘main-sequence’, a fairly clear picture is emerging. Independent of whether galaxy-integrated quantities or surface densities are considered, low- and high-z SFG populations appear to follow similar molecular gas–star formation relations with slopes 1.1 to 1.2, over three orders of magnitude in gas mass or surface density. The gas-depletion time-scale in these SFGs grows from 0.5 Gyr at z∼ 2 to 1.5 Gyr at z∼ 0. The average corresponds to a fairly low star formation efficiency of 2 per cent per dynamical time. Because star formation depletion times are significantly smaller than the Hubble time at all redshifts sampled, star formation rates and gas fractions are set by the balance between gas accretion from the halo and stellar feedback. In contrast, very luminous and ultraluminous, gas-rich major mergers at both low and high z produce on average four to 10 times more far-infrared luminosity per unit gas mass. We show that only some fraction of this difference can be explained by uncertainties in gas mass or luminosity estimators; much of it must be intrinsic. A possible explanation is a top-heavy stellar mass function in the merging systems but the most likely interpretation is that the star formation relation is driven by global dynamical effects. For a given mass, the more compact merger systems produce stars more rapidly because their gas clouds are more compressed with shorter dynamical times, so that they churn more quickly through the available gas reservoir than the typical normal disc galaxies. When the dependence on galactic dynamical time-scale is explicitly included, disc galaxies and mergers appear to follow similar gas-to-star formation relations. The mergers may be forming stars at slightly higher efficiencies than the discs.

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