THE EVOLUTION of the GALAXY STELLAR MASS FUNCTION at z = 4-8: A STEEPENING LOW-MASS-END SLOPE with INCREASING REDSHIFT

Mimi Song, Steven L. Finkelstein, Matthew L.N. Ashby, A. Grazian, Yu Lu, Casey Papovich, Brett Salmon, Rachel Somerville, Mark Dickinson, K. Duncan, Sandy M. Faber, Giovanni G. Fazio, Henry C. Ferguson, Adriano Fontana, Yicheng Guo, Nimish Hathi, Seong Kook Lee, Emiliano Merlin, S. P. Willner

Research output: Contribution to journalArticlepeer-review

126 Scopus citations

Abstract

We present galaxy stellar mass functions (GSMFs) at z = 4-8 from a rest-frame ultraviolet (UV) selected sample of ∼4500 galaxies, found via photometric redshifts over an area of ∼280 arcmin2 in the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS)/Great Observatories Origins Deep Survey (GOODS) fields and the Hubble Ultra Deep Field. The deepest Spitzer/IRAC data to date and the relatively large volume allow us to place a better constraint at both the low- and high-mass ends of the GSMFs compared to previous space-based studies from pre-CANDELS observations. Supplemented by a stacking analysis, we find a linear correlation between the rest-frame UV absolute magnitude at 1500 Å () and logarithmic stellar mass () that holds for galaxies with . We use simulations to validate our method of measuring the slope of the -M UV relation, finding that the bias is minimized with a hybrid technique combining photometry of individual bright galaxies with stacked photometry for faint galaxies. The resultant measured slopes do not significantly evolve over z = 4-8, while the normalization of the trend exhibits a weak evolution toward lower masses at higher redshift. We combine the -M UV distribution with observed rest-frame UV luminosity functions at each redshift to derive the GSMFs, finding that the low-mass-end slope becomes steeper with increasing redshift from at z = 4 to at z = 8. The inferred stellar mass density, when integrated over -1013 M Ȯ, increases by a factor of between z = 7 and z = 4 and is in good agreement with the time integral of the cosmic star formation rate density.

Original languageEnglish (US)
Article number5
JournalAstrophysical Journal
Volume825
Issue number1
DOIs
StatePublished - Jul 1 2016

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Galaxies: evolution
  • galaxies: formation
  • galaxies: high-redshift
  • galaxies: luminosity function
  • mass function

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