(UV) selected sample of∼ 4500 galaxies, found via photometric redshifts over an area of∼ 280 arcmin 2 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 …
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 arcmin 2 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 –10 13 M⊙, 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.