Evolution of the Stellar Mass Function and Infrared Luminosity Function of Galaxies since z = 1.2

Abstract

Abstract We measured evolution of the K-band luminosity function and stellar mass function (SMF) for red and blue galaxies at z < 1.2 using a sample of 353 594 I < 24 galaxies in 8.26 square degrees of Boötes. We addressed several sources of systematic and random error in measurements of total galaxy light, photometric redshift, and absolute magnitude. We have found that the K-band luminosity density for both red and blue galaxies increased by a factor of 1.2 from z ∼ 1.1 to z ∼ 0.3, while the most luminous red (blue) galaxies decreased in luminosity by 0.19(0.33) mag or ×0.83(0.74). These results are consistent with z < 0.2 studies, while our large sample size and area result in smaller Poisson and cosmic variance uncertainties than most z > 0.4 luminosity and mass function measurements. Using an evolving relation for K-band mass-to-light ratios as a function of (B−V) color, we found a slowly decreasing rate of growth in red galaxy stellar mass density of ×2.3 from z ∼ 1.1 to z ∼ 0.3, indicating a slowly decreasing rate of migration from the blue cloud to the red sequence. Unlike some studies of the SMF, we find that massive red galaxies grow by a factor of ×1.7 from z ∼ 1.1 to z ∼ 0.3, with the rate of growth due to mergers decreasing with time. These results are comparable with measurements of merger rates and clustering, and they are also consistent with the red galaxy stellar mass growth implied by comparing K-band luminosity evolution with the fading of passive stellar population models.