LUMINOUS AND HIGH STELLAR MASS CANDIDATE GALAXIES AT z ≈ 8 DISCOVERED IN THE COSMIC ASSEMBLY NEAR-INFRARED DEEP EXTRAGALACTIC LEGACY SURVEY

One key goal of the Hubble Space Telescope Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey is to track galaxy evolution back to z ≈ 8. Its two-tiered “wide and deep” strategy bridges significant gaps in existing near-infrared surveys. Here we report on z ≈ 8 galaxy candidates selected as F105W-band dropouts in one of its deep fields, which covers 50.1 arcmin2 to 4 ks depth in each of three near-infrared bands in the Great Observatories Origins Deep Survey southern field. Two of our candidates have J < 26.2 mag, and are >1 mag brighter than any previously known F105W-dropouts. We derive constraints on the bright end of the rest-frame ultraviolet luminosity function of galaxies at z ≈ 8, and show that the number density of such very bright objects is higher than expected from the previous Schechter luminosity function estimates at this redshift. Another two candidates are securely detected in Spitzer Infrared Array Camera images, which are the first such individual detections at z ≈ 8. Their derived stellar masses are on the order of a few × 109 M☉, from which we obtain the first measurement of the high-mass end of the galaxy stellar mass function at z ≈ 8. The high number density of very luminous and very massive galaxies at z ≈ 8, if real, could imply a large stellar-to-halo mass ratio and an efficient conversion of baryons to stars at such an early time.

[1]  O. Lahav,et al.  A CENSUS OF STAR-FORMING GALAXIES IN THE Z ∼ 9–10 UNIVERSE BASED ON HST+SPITZER OBSERVATIONS OVER 19 CLASH CLUSTERS: THREE CANDIDATE Z ∼ 9–10 GALAXIES AND IMPROVED CONSTRAINTS ON THE STAR FORMATION RATE DENSITY AT Z ∼ 9.2 , 2012, 1211.2230.

[2]  H. Ferguson,et al.  NEAR-INFRARED SURVEY OF THE GOODS-NORTH FIELD: SEARCH FOR LUMINOUS GALAXY CANDIDATES AT z ≳ 6.5, , 2012, 1207.5798.

[3]  J. P. U. Fynbo,et al.  Edinburgh Research Explorer Discovery of bright z 7 galaxies in the UltraVISTA survey , 2012 .

[4]  S. Ammons,et al.  OPTIMAL MASS CONFIGURATIONS FOR LENSING HIGH-REDSHIFT GALAXIES , 2012, 1203.2614.

[5]  P. Ho,et al.  THE TAIWAN ECDFS NEAR-INFRARED SURVEY: VERY BRIGHT END OF THE LUMINOSITY FUNCTION AT z > 7 , 2012, 1202.1576.

[6]  R. Bouwens,et al.  The Bright End of the UV Luminosity Function at z~8: New Constraints from CANDELS Data , 2012 .

[7]  M. Franx,et al.  THE BRIGHT END OF THE ULTRAVIOLET LUMINOSITY FUNCTION AT z ∼ 8: NEW CONSTRAINTS FROM CANDELS DATA IN GOODS-SOUTH , 2012, 1201.0755.

[8]  C. Conselice,et al.  CANDELS: THE EVOLUTION OF GALAXY REST-FRAME ULTRAVIOLET COLORS FROM z = 8 TO 4 , 2011, 1110.3785.

[9]  R. Bouwens,et al.  OVERDENSITIES OF Y-DROPOUT GALAXIES FROM THE BRIGHTEST-OF-REIONIZING GALAXIES SURVEY: A CANDIDATE PROTOCLUSTER AT REDSHIFT z ≈ 8 , 2011, 1110.0468.

[10]  Hooshang Nayyeri,et al.  SPECTROSCOPIC CONFIRMATION OF THREE z-DROPOUT GALAXIES AT z = 6.844–7.213: DEMOGRAPHICS OF Lyα EMISSION IN z ∼ 7 GALAXIES , 2011, 1107.3159.

[11]  M. Jarvis,et al.  Star-forming galaxies at z approximate to 8-9 from Hubble Space Telescope/WFC3: implications for reionization , 2011 .

[12]  S. Ravindranath,et al.  CANDELS: THE COSMIC ASSEMBLY NEAR-INFRARED DEEP EXTRAGALACTIC LEGACY SURVEY—THE HUBBLE SPACE TELESCOPE OBSERVATIONS, IMAGING DATA PRODUCTS, AND MOSAICS , 2011, 1105.3753.

[13]  D. Wittman,et al.  HUBBLE SPACE TELESCOPE OBSERVATIONS OF FIELD ULTRACOOL DWARFS AT HIGH GALACTIC LATITUDE , 2011, 1105.2567.

[14]  Y. Mellier,et al.  Optical dropout galaxies lensed by the cluster A2667 , 2011, 1104.2520.

[15]  R. Bouwens,et al.  THROUGH THE LOOKING GLASS: BRIGHT, HIGHLY MAGNIFIED GALAXY CANDIDATES AT z ∼ 7 BEHIND A1703 , 2011, 1104.2035.

[16]  S. Wilkins,et al.  New star-forming galaxies at z≈ 7 from Wide Field Camera Three imaging , 2011 .

[17]  J. Cuby,et al.  USING THE BULLET CLUSTER AS A GRAVITATIONAL TELESCOPE TO STUDY z ≳ 7 LYMAN BREAK GALAXIES , 2011, 1101.4677.

[18]  R. Windhorst,et al.  A distortion of very-high-redshift galaxy number counts by gravitational lensing , 2011, Nature.

[19]  M. Franx,et al.  A candidate redshift z ≈ 10 galaxy and rapid changes in that population at an age of 500 Myr , 2009, Nature.

[20]  Leiden,et al.  Quenching massive galaxies with on-the-fly feedback in cosmological hydrodynamic simulations , 2010, 1012.3166.

[21]  J. W. MacKenty,et al.  THE BRIGHTEST OF REIONIZING GALAXIES SURVEY: DESIGN AND PRELIMINARY RESULTS , 2010, 1011.4075.

[22]  Z. Cai,et al.  PROBING VERY BRIGHT END OF GALAXY LUMINOSITY FUNCTION AT z ≳ 7 USING HUBBLE SPACE TELESCOPE PURE PARALLEL OBSERVATIONS , 2010, 1010.2261.

[23]  R. Bouwens,et al.  EVOLUTION OF GALAXY STELLAR MASS FUNCTIONS, MASS DENSITIES, AND MASS-TO-LIGHT RATIOS FROM z ∼ 7 TO z ∼ 4 , 2010, 1008.3901.

[24]  J. Cuby,et al.  The bright end of the z ~ 7 UV luminosity function from a wide and deep HAWK-I survey , 2010, 1007.5396.

[25]  H. Ferguson,et al.  The rising star formation histories of distant galaxies and implications for gas accretion with time , 2010, 1007.4554.

[26]  Jay Anderson,et al.  An Empirical Pixel-Based Correction for Imperfect CTE. I. HST’s Advanced Camera for Surveys , 2010, 1007.3987.

[27]  M. Franx,et al.  ULTRAVIOLET LUMINOSITY FUNCTIONS FROM 132 z ∼ 7 AND z ∼ 8 LYMAN-BREAK GALAXIES IN THE ULTRA-DEEP HUDF09 AND WIDE-AREA EARLY RELEASE SCIENCE WFC3/IR OBSERVATIONS , 2010, 1006.4360.

[28]  M. Jarvis,et al.  Candidate z~8-9 Galaxies from WFC3 Imaging , 2010, 1006.3545.

[29]  M. Dopita,et al.  THE HUBBLE SPACE TELESCOPE WIDE FIELD CAMERA 3 EARLY RELEASE SCIENCE DATA: PANCHROMATIC FAINT OBJECT COUNTS FOR 0.2–2 μm WAVELENGTH , 2010, 1005.2776.

[30]  S. Wilkins,et al.  New Star Forming Galaxies at z\approx 7 from WFC3 Imaging , 2010, 1002.4866.

[31]  C. Steidel,et al.  DUST OBSCURATION AND METALLICITY AT HIGH REDSHIFT: NEW INFERENCES FROM UV, Hα, AND 8 μm OBSERVATIONS OF z ∼ 2 STAR-FORMING GALAXIES , 2010, 1002.0837.

[32]  A. Dekel,et al.  Survival of star-forming giant clumps in high-redshift galaxies , 2010, 1001.0765.

[33]  Princeton University.,et al.  A COMPREHENSIVE ANALYSIS OF UNCERTAINTIES AFFECTING THE STELLAR MASS–HALO MASS RELATION FOR 0 < z < 4 , 2010, 1001.0015.

[34]  H. Ferguson,et al.  ON THE STELLAR POPULATIONS AND EVOLUTION OF STAR-FORMING GALAXIES AT 6.3 < z ⩽ 8.6 , 2009, 0912.1338.

[35]  M. Franx,et al.  STAR FORMATION RATES AND STELLAR MASSES OF z = 7–8 GALAXIES FROM IRAC OBSERVATIONS OF THE WFC3/IR EARLY RELEASE SCIENCE AND THE HUDF FIELDS , 2009, 0911.1356.

[36]  R. O’Connell,et al.  Galaxy formation in the reionization epoch as hinted by wide field camera 3 observations of the hubble ultra deep field , 2009, 0910.0077.

[37]  Oxford,et al.  Constraints on star-forming galaxies at z≥ 6.5 from HAWK-I Y-band imaging of GOODS-South , 2009, 0909.4205.

[38]  M. Franx,et al.  ULTRADEEP INFRARED ARRAY CAMERA OBSERVATIONS OF SUB-L* z ∼ 7 AND z ∼ 8 GALAXIES IN THE HUBBLE ULTRA DEEP FIELD: THE CONTRIBUTION OF LOW-LUMINOSITY GALAXIES TO THE STELLAR MASS DENSITY AND REIONIZATION , 2009, 0910.0838.

[39]  Y.Tanaguchi,et al.  SPECTROSCOPY OF LUMINOUS z > 7 GALAXY CANDIDATES AND SOURCES OF CONTAMINATION IN z > 7 GALAXY SEARCHES , 2009, 0910.0444.

[40]  M. Franx,et al.  STRUCTURE AND MORPHOLOGIES OF z ∼ 7–8 GALAXIES FROM ULTRA-DEEP WFC3/IR IMAGING OF THE HUBBLE ULTRA-DEEP FIELD , 2009, 0909.5183.

[41]  Mark Lacy,et al.  The contribution of high-redshift galaxies to cosmic reionization: New results from deep WFC3 imaging of the Hubble Ultra Deep Field , 2009, 0909.2255.

[42]  J. Dunlop,et al.  Galaxies at z = 6 - 9 from the WFC3/IR imaging of the HUDF , 2009, 0909.2437.

[43]  M. Franx,et al.  DISCOVERY OF z ∼ 8 GALAXIES IN THE HUBBLE ULTRA DEEP FIELD FROM ULTRA-DEEP WFC3/IR OBSERVATIONS , 2009, 0909.1803.

[44]  S. M. Fall,et al.  LARGE AREA SURVEY FOR z = 7 GALAXIES IN SDF AND GOODS-N: IMPLICATIONS FOR GALAXY FORMATION AND COSMIC REIONIZATION , 2009, 0908.3191.

[45]  R. Teyssier,et al.  Cold streams in early massive hot haloes as the main mode of galaxy formation , 2008, Nature.

[46]  P. Hopkins,et al.  A semi-analytic model for the co-evolution of galaxies, black holes and active galactic nuclei , 2008, 0808.1227.

[47]  Paolo Coppi,et al.  EAZY: A Fast, Public Photometric Redshift Code , 2008, 0807.1533.

[48]  I. Smail,et al.  THE CHANDRA DEEP FIELD-SOUTH SURVEY: 4 Ms SOURCE CATALOGS , 2008, 0806.3968.

[49]  M. Stiavelli,et al.  Cosmic Variance and Its Effect on the Luminosity Function Determination in Deep High-z Surveys , 2007, 0712.0398.

[50]  M. Franx,et al.  Discovery of a Very Bright Strongly Lensed Galaxy Candidate at z ≈ 7.6 , 2007, 0802.2506.

[51]  J. Kneib,et al.  Constraining the population of 6 < z < 10 star-forming galaxies with deep near-IR images of lensing clusters , 2006, astro-ph/0606134.

[52]  A. Meiksin.  Colour corrections for high-redshift objects due to intergalactic attenuation , 2005, astro-ph/0512435.

[53]  C. Conselice,et al.  Rest-Frame Ultraviolet-to-Optical Properties of Galaxies at z ≈ 6 and z ≈ 5 in the Hubble Ultra Deep Field: From Hubble to Spitzer , 2005, astro-ph/0507673.

[54]  S. M. Fall,et al.  High-Redshift Extremely Red Objects in the Hubble Space Telescope Ultra Deep Field Revealed by the GOODS Infrared Array Camera Observations , 2004, astro-ph/0408070.

[55]  Padova,et al.  Color-selected Galaxies at z ≈ 6 in the Great Observatories Origins Deep Survey , 2003, astro-ph/0309070.

[56]  G. Bruzual,et al.  Stellar population synthesis at the resolution of 2003 , 2003, astro-ph/0309134.

[57]  S. M. Fall,et al.  The Great Observatories Origins Deep Survey: Initial Results from Optical and Near-Infrared Imaging , 2003, astro-ph/0309105.

[58]  M. Giavalisco,et al.  Lyman Break Galaxies at Redshift z ~ 3: Survey Description and Full Data Set , 2003, astro-ph/0305378.

[59]  Massimo Stiavelli,et al.  The Hubble Ultra Deep Field , 2003, astro-ph/0607632.

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

[61]  et al,et al.  Infrared Photometry of Late-M, L, and T Dwarfs , 2001, astro-ph/0108435.

[62]  D. Calzetti.  The Dust Opacity of Star‐forming Galaxies , 2001, astro-ph/0109035.

[63]  Cambridge,et al.  ∼ 4 and the Evolution of the Uv Luminosity Density at High Redshift , 2022 .

[64]  A. J. Connolly,et al.  Simultaneous Multicolor Detection of Faint Galaxies in the Hubble Deep Field , 1998, astro-ph/9811086.

[65]  E. Bertin,et al.  SExtractor: Software for source extraction , 1996 .

[66]  Piero Madau,et al.  Radiative transfer in a clumpy universe: The colors of high-redshift galaxies , 1995 .

[67]  R. Kron.  Photometry of a complete sample of faint galaxies. , 1980 .

[68]  E. Salpeter.  The Luminosity function and stellar evolution , 1955 .