DEMONSTRATING DIVERSITY IN STAR-FORMATION HISTORIES WITH THE CSI SURVEY

We present coarse but robust star-formation histories (SFHs) derived from spectrophotometric data of the Carnegie-Spitzer-IMACS Survey, for 22,494 galaxies at with stellar masses of 109 M⊙ to 1012 M⊙. Our study moves beyond “average” SFHs and distribution functions of specific star-formation rates (sSFRs) to individually measured SFHs for tens of thousands of galaxies. By comparing star-formation rates (SFRs) with timescales of , and 108 years, we find a wide diversity of SFHs: “old galaxies” that formed most or all of their stars early, galaxies that formed stars with declining or constant SFRs over a Hubble time, and genuinely “young galaxies” that formed most of their stars since z = 1. This sequence is one of decreasing stellar mass, but remarkably, each type is found over a mass range of a factor of 10. Conversely, galaxies at any given mass follow a wide range of SFHs, leading us to conclude that (1) halo mass does not uniquely determine SFHs, (2) there is no “typical” evolutionary track, and (3) “abundance matching” has limitations as a tool for inferring physics. Our observations imply that SFHs are set at an early epoch, and that—for most galaxies—the decline and cessation of star formation occurs over a Hubble time, without distinct “quenching” events. SFH diversity is inconsistent with models where galaxy mass, at any given epoch, grows simply along relations between SFR and stellar mass, but is consistent with a two-parameter lognormal form, lending credence to this model from a new and independent perspective.

[1]  K. Glazebrook,et al.  DIFFERENCES IN THE STRUCTURAL PROPERTIES AND STAR FORMATION RATES OF FIELD AND CLUSTER GALAXIES AT Z ∼ 1 , 2016, 1605.05314.

[2]  A. Dressler,et al.  RETURN TO [Log-]NORMALCY: RETHINKING QUENCHING, THE STAR FORMATION MAIN SEQUENCE, AND PERHAPS MUCH MORE , 2016, 1604.00016.

[3]  A. Fontana,et al.  THE GRISM LENS-AMPLIFIED SURVEY FROM SPACE (GLASS). V. EXTENT AND SPATIAL DISTRIBUTION OF STAR FORMATION IN z ∼ 0.5 CLUSTER GALAXIES , 2015, 1511.00686.

[4]  M. Donahue,et al.  PRECIPITATION-REGULATED STAR FORMATION IN GALAXIES , 2015, 1505.03592.

[5]  J. Trump,et al.  CAUGHT IN THE ACT: GAS AND STELLAR VELOCITY DISPERSIONS IN A FAST QUENCHING COMPACT STAR-FORMING GALAXY AT z ∼ 1.7 , 2015, 1503.07164.

[6]  M. Donahue,et al.  SUPERNOVA SWEEPING AND BLACK HOLE FEEDBACK IN ELLIPTICAL GALAXIES , 2015, 1503.02104.

[7]  M. Donahue,et al.  Regulation of star formation in giant galaxies by precipitation, feedback and conduction , 2014, Nature.

[8]  Matching the Evolution of the Stellar Mass Function Using Log-normal Star Formation Histories , 2014, 1411.1431.

[9]  G. Fasano,et al.  FROM BLUE STAR-FORMING TO RED PASSIVE: GALAXIES IN TRANSITION IN DIFFERENT ENVIRONMENTS , 2014, 1410.6481.

[10]  G. Brammer,et al.  CONSTRAINING THE LOW-MASS SLOPE OF THE STAR FORMATION SEQUENCE AT 0.5 < z < 2.5 , 2014, 1407.1843.

[11]  D. Kelson.  Decoding the Star-Forming Main Sequence or: How I Learned to Stop Worrying and Love the Central Limit Theorem , 2014, 1406.5191.

[12]  O. I. Wong,et al.  The green valley is a red herring: Galaxy Zoo reveals two evolutionary pathways towards quenching of star formation in early-and late-type galaxies , 2014, 1402.4814.

[13]  Stefano Andreon,et al.  SPECTROSCOPIC CONFIRMATION OF THE RICH z = 1.80 GALAXY CLUSTER JKCS 041 USING THE WFC3 GRISM: ENVIRONMENTAL TRENDS IN THE AGES AND STRUCTURE OF QUIESCENT GALAXIES , 2013, 1310.6754.

[14]  S. E. Persson,et al.  GALAXY STELLAR MASS FUNCTIONS FROM ZFOURGE/CANDELS: AN EXCESS OF LOW-MASS GALAXIES SINCE z = 2 AND THE RAPID BUILDUP OF QUIESCENT GALAXIES , 2013, 1309.5972.

[15]  D. Kelson,et al.  THE CARNEGIE–SPITZER–IMACS REDSHIFT SURVEY OF GALAXY EVOLUTION SINCE z = 1.5. I. DESCRIPTION AND METHODOLOGY , 2012, 1201.0783.

[16]  M. Dickinson,et al.  Cosmic Star-Formation History , 1996, 1403.0007.

[17]  A. Dressler,et al.  THE IMACS CLUSTER BUILDING SURVEY. III. THE STAR FORMATION HISTORIES OF FIELD GALAXIES , 2013, 1303.3916.

[18]  D. Kelson,et al.  THE IMACS CLUSTER BUILDING SURVEY. I. DESCRIPTION OF THE SURVEY AND ANALYSIS METHODS , 2013, 1303.3915.

[19]  A. Dressler,et al.  THE IMACS CLUSTER BUILDING SURVEY. IV. THE LOG-NORMAL STAR FORMATION HISTORY OF GALAXIES , 2013, 1303.3917.

[20]  R. Wechsler,et al.  THE AVERAGE STAR FORMATION HISTORIES OF GALAXIES IN DARK MATTER HALOS FROM z = 0–8 , 2012, 1207.6105.

[21]  G. Brammer,et al.  THE STAR FORMATION MASS SEQUENCE OUT TO z = 2.5 , 2012, 1205.0547.

[22]  T. Lauer,et al.  THE PANCHROMATIC HUBBLE ANDROMEDA TREASURY , 2012, 1204.0010.

[23]  D. Kelson,et al.  A DIRECT MEASUREMENT OF HIERARCHICAL GROWTH IN GALAXY GROUPS SINCE z ∼ 1 , 2012, 1201.1009.

[24]  Samuel N. Leitner.  ON THE LAST 10 BILLION YEARS OF STELLAR MASS GROWTH IN STAR-FORMING GALAXIES , 2011, 1108.0938.

[25]  D. Kelson,et al.  IMACS: The Inamori-Magellan Areal Camera and Spectrograph on Magellan-Baade , 2011 .

[26]  B. Garilli,et al.  MASS AND ENVIRONMENT AS DRIVERS OF GALAXY EVOLUTION IN SDSS AND zCOSMOS AND THE ORIGIN OF THE SCHECHTER FUNCTION , 2010, 1003.4747.

[27]  J. Gunn,et al.  THE PROPAGATION OF UNCERTAINTIES IN STELLAR POPULATION SYNTHESIS MODELING. III. MODEL CALIBRATION, COMPARISON, AND EVALUATION , 2009, 0911.3151.

[28]  M. Franx,et al.  SUBMITTED TO THE ASTROPHYSICAL JOURNAL Preprint typeset using LATEX style emulateapj v. 10/09/06 DETECTION OF QUIESCENT GALAXIES IN A BICOLOR SEQUENCE FROM Z = 0 − 2 , 2022 .

[29]  R. Wechsler,et al.  SUBMITTED TO THE ASTROPHYSICAL JOURNAL Preprint typeset using LATEX style emulateapj v. 10/09/06 CONNECTING GALAXIES, HALOS, AND STAR FORMATION RATES ACROSS COSMIC TIME , 2008 .

[30]  J. Gunn,et al.  THE ASTROPHYSICAL JOURNAL Preprint typeset using LATEX style emulateapj v. 10/09/06 THE PROPAGATION OF UNCERTAINTIES IN STELLAR POPULATION SYNTHESIS MODELING I: THE RELEVANCE OF UNCERTAIN ASPECTS OF STELLAR EVOLUTION AND THE IMF TO THE DERIVED PHYSICAL PR , 2022 .

[31]  A. Pasquali,et al.  Satellite Ecology: The Dearth of Environment Dependence , 2008, 0805.0002.

[32]  Columbia,et al.  Star Formation in AEGIS Field Galaxies since z = 1.1: The Dominance of Gradually Declining Star Formation, and the Main Sequence of Star-forming Galaxies , 2007, astro-ph/0701924.

[33]  A. Helmi,et al.  FROM STARS TO GALAXIES: BUILDING THE PIECES TO BUILD UP THE UNIVERSE , 2007 .

[34]  C. Maraston.  Evolutionary population synthesis: models, analysis of the ingredients and application to high‐z galaxies , 2004, astro-ph/0410207.

[35]  A. Dekel,et al.  Galaxy bimodality due to cold flows and shock heating , 2004, astro-ph/0412300.

[36]  G. Chabrier.  Galactic Stellar and Substellar Initial Mass Function , 2003, astro-ph/0304382.

[37]  Ronald G. Probst,et al.  NEWFIRM: the widefield IR imager for NOAO 4-m telescopes , 2003, SPIE Astronomical Telescopes + Instrumentation.

[38]  R. Davé,et al.  How do galaxies get their gas , 2002, astro-ph/0407095.

[39]  H. Mo,et al.  Linking early‐ and late‐type galaxies to their dark matter haloes , 2002, astro-ph/0210495.

[40]  O. Fèvre,et al.  The Canada-France Redshift Survey: The Luminosity Density and Star Formation History of the Universe to z ~ 1 , 1996, astro-ph/9601050.

[41]  S. M. Fall,et al.  Cosmic chemical evolution , 1995 .

[42]  K. Lanzetta,et al.  EVOLUTION OF THE GASEOUS CONTENT OF THE UNIVERSE , 1993 .

[43]  A. Dressler.  Galaxy morphology in rich clusters: Implications for the formation and evolution of galaxies , 1980 .