THE EVOLUTION OF THE GALAXY STELLAR MASS FUNCTION AT z = 4–8: A STEEPENING LOW-MASS-END SLOPE WITH INCREASING REDSHIFT Academic Article uri icon

abstract

  • © 2016. The American Astronomical Society. All rights reserved. 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.

author list (cited authors)

  • Song, M., Finkelstein, S. L., Ashby, M., Grazian, A., Lu, Y. u., Papovich, C., ... Willner, S. P.

publication date

  • January 1, 2016 11:11 AM