PRIMUS: CONSTRAINTS ON STAR FORMATION QUENCHING AND GALAXY MERGING, AND THE EVOLUTION OF THE STELLAR MASS FUNCTION FROM z=0-1

We measure the evolution of the stellar mass function (SMF) from z = 0-1 using multi-wavelength imaging and spectroscopic redshifts from the PRismMUlti-object Survey (PRIMUS) and the Sloan Digital Sky Survey (SDSS). From PRIMUS we construct an i < 23 flux-limited sample of similar to 40,000 galaxies at z = 0.2-1.0 over five fields totaling approximate to 5.5 deg(2), and from the SDSS we select similar to 170,000 galaxies at z = 0.01-0.2 that we analyze consistently with respect to PRIMUS to minimize systematic errors in our evolutionary measurements. We find that the SMF of all galaxies evolves relatively little since z = 1, although we do find evidence for mass assembly downsizing; we measure a approximate to 30% increase in the number density of similar to 10(10) M-circle dot galaxies since z approximate to 0.6, and a less than or similar to 10% change in the number density of all greater than or similar to 10(11) M-circle dot galaxies since z approximate to 1. Dividing the sample into star-forming and quiescent using an evolving cut in specific star formation rate, we find that the number density of similar to 10(10) M-circle dot star-forming galaxies stays relatively constant since z approximate to 0.6, whereas the space density of greater than or similar to 10(11) M-circle dot star-forming galaxies decreases by similar to 50% between z approximate to 1 and z approximate to 0. Meanwhile, the number density of similar to 10(10) M-circle dot quiescent galaxies increases steeply toward low redshift, by a factor of similar to 2-3 since z approximate to 0.6, while the number of massive quiescent galaxies remains approximately constant since z approximate to 1. These results suggest that the rate at which star-forming galaxies are quenched increases with decreasing stellar mass, but that the bulk of the stellar mass buildup within the quiescent population occurs around similar to 10(10.8) M-circle dot. In addition, we conclude that mergers do not appear to be a dominant channel for the stellar mass buildup of galaxies at z < 1, even among massive (greater than or similar to 10(11) M-circle dot) quiescent galaxies.