EVOLUTION OF STAR FORMATION PROPERTIES OF HIGH-REDSHIFT CLUSTER GALAXIES SINCE z = 2

Using a stellar mass-limited sample of ∼46,600 galaxies () at , we show that the stellar mass, rather than the environment, is the main parameter controlling quenching of star formation in galaxies with out to z = 2. On the other hand, the environmental quenching becomes efficient at regardless of galaxy mass, and it serves as a main mechanism for quenching star formation for lower mass galaxies. Our result is based on deep optical and near-infrared imaging data over 2800 arcmin2, enabling us to negate cosmic variance and identify 46 galaxy cluster candidates with . From to , the fraction of quiescent galaxies increases by a factor of ∼10 over the entire redshift range, but the difference between cluster and field environment is negligible. Rapid evolution in the quiescent fraction is seen from z = 2 to z = 1.3 for massive galaxies, suggesting a build-up of massive quiescent galaxies at . For galaxies with at , the quiescent fraction is found to be as much as a factor of 2 larger in clusters than in field, showing the importance of environmental quenching in low-mass galaxies at low redshift. Most high-mass galaxies are already quenched at , therefore environmental quenching does not play a significant role for them, although the efficiency of environmental quenching is nearly identical between high- and low-mass galaxies.