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Title: A study of massive and evolved galaxies at high redshift

We use data taken as part of Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3) observations of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) to identify massive and evolved galaxies at 3 < z < 4.5. This is performed using the strength of the Balmer break feature at rest-frame 3648 Å, which is a diagnostic of the age of the stellar population in galaxies. Using the WFC3 H-band-selected catalog for the CANDELS GOODS-S field and deep multi-waveband photometry from optical (HST) to mid-infrared (Spitzer) wavelengths, we identify a population of old and evolved post-starburst galaxies based on the strength of their Balmer breaks (Balmer break galaxies, BBGs). The galaxies are also selected to be bright in rest-frame near-IR wavelengths and hence massive. We identify a total of 16 BBGs. Fitting the spectral energy distribution of the BBGs shows that the candidate galaxies have average estimated ages of ∼800 Myr and average stellar masses of ∼5 × 10{sup 10} M {sub ☉}, consistent with being old and massive systems. Two of our BBG candidates are also identified by the criteria that are sensitive to star-forming galaxies (Lyman break galaxy selection). We find a number density of ∼3.2 × 10{supmore » –5} Mpc{sup –3} for the BBGs, corresponding to a mass density of ∼2.0 × 10{sup 6} M {sub ☉} Mpc{sup –3} in the redshift range covering the survey. Given the old age and the passive evolution, it is argued that some of these objects formed the bulk of their mass only a few hundred million years after the big bang.« less
Authors:
; ; ;  [1] ; ; ; ; ;  [2] ;  [3] ;  [4] ; ;  [5] ; ;  [6] ; ;  [7] ;  [8] ; ;  [9]
  1. University of California Riverside, Riverside, CA 92512 (United States)
  2. Space Telescope Science Institute, Baltimore, MD 21218 (United States)
  3. National Optical Astronomy Observatory, Tucson, AZ 85719 (United States)
  4. University of Massachusetts Amherst, Amherst, MA 01003 (United States)
  5. INAF-Osservatorio Astronomico di Roma, Via Frascati 33 Monte Porzio Catone, 00040 Rome (Italy)
  6. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)
  7. University of California Santa Cruz, Santa Cruz, CA 95064 (United States)
  8. Laboratoire d'Astrophysique de Marseille, rue Frédéric Joliot Curie, 13013 Marseille (France)
  9. Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom)
Publication Date:
OSTI Identifier:
22370466
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 794; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CATALOGS; DENSITY; ENERGY SPECTRA; EVOLUTION; GALAXIES; MASS; PHOTOMETRY; RED SHIFT; SPACE; STARS; TELESCOPES; WAVELENGTHS