DIFFERENCES IN THE STRUCTURAL PROPERTIES AND STAR FORMATION RATES OF FIELD AND CLUSTER GALAXIES AT Z ∼ 1

Abstract

ABSTRACT We investigate the dependence of galaxy sizes and star formation rates (SFRs) on their environment using a mass-limited sample of quiescent and star-forming galaxies with log(M */ ) ≥ 9.5 at selected from the NEWFIRM medium-band Survey (NMBS). Using the Galaxy Environment Evolution Collaboration 2 spectroscopic cluster catalog and the accurate photometric redshifts from the NMBS, we select quiescent and star-forming cluster ( km s−1) galaxies within two virial radius, R vir, intervals of 2 > R vir > 0.5 and R vir < 0.5. Galaxies residing outside of the 2 R vir of both the cluster centers and the additional candidate over-densities are defined as our field sample. Galaxy structural parameters are measured from the COSMOS legacy Hubble Space Telescope/ACS F814W image. The sizes and Sérsic indices of quiescent field and cluster galaxies have the same distribution regardless of R vir. However, cluster star-forming galaxies within 0.5 R vir have lower mass-normalized average sizes by , and a higher fraction of Sérsic indices with , than field star-forming galaxies. The average SFRs of star-forming cluster galaxies show a trend of decreasing SFR with clustocentric radius. The mass-normalized average SFR of cluster star-forming galaxies is a factor of ( ) lower than that of star-forming galaxies in the field. While we find no significant dependence on environment for quiescent galaxies, the properties of star-forming galaxies are affected, which could be the result of environment acting on their gas content.