First results on the cluster galaxy population from the Subaru Hyper Suprime-Cam survey. I. The role of group or cluster environment in star formation quenching from z = 0.2 to 1.1

Abstract

Abstract We utilize the Hyper Suprime-Cam (HSC) CAMIRA cluster catalog (Oguri et al. 2018 PASJ, 70, S20) and the photo-z galaxy catalog constructed in the HSC Wide field (S16A), covering ∼174 deg2, to study the star formation activity of galaxies in different environments over 0.2 < z < 1.1. We probe galaxies down to i ∼ 26, corresponding to a stellar mass limit of log10(M*/M⊙) ∼ 8.2 and ∼8.6 for star-forming and quiescent populations, respectively, at z ∼ 0.2. The existence of the red sequence for low stellar mass galaxies in clusters suggests that the environmental quenching persists to halt the star formation in the low-mass regime. In addition, star-forming galaxies in groups or clusters are systematically biased toward lower values of specific star formation rate by 0.1–0.3 dex with respect to those in the field, and the offsets show no strong redshift evolution over our redshift range, implying a universal slow quenching mechanism acting in the dense environments since z ∼ 1.1. Moreover, the environmental quenching dominates the mass quenching in low-mass galaxies, and the quenching dominance reverses in high-mass ones. The transition mass is greater in clusters than in groups, indicating that the environmental quenching is more effective for massive galaxies in clusters compared to groups.