Revealing galaxy quenching's dependence on stellar mass and environment in galaxy clusters

Quenching is a vital phase in galaxy evolution. A key population, recently-quenched galaxy(RQG) can convey information directly from the quenching process. In this work, we investigate RQGs in clusters. They span from cluster centers to outskirts. From galaxy overdensities in the COSMOS field, we pick out 14 galaxy clusters and determine their center coordinates from 5 redshift bins at z~0.5-1.0. Our galaxy sample consists of galaxies within a 1.25 Mpc radius from these cluster centers. Using photometric data from the COSMOS2015 catalog and rest-frame UVJ selection method, we classify all galaxies into star-forming, quiescent, and recently-quenched populations. We use number ratios of different populations to quantify properties of quenching processes. In particular, we use model evolutionary tracks on the UVJ diagram to distinguish fast and slow quenching paths hence understand the quenching timescale's dependence on mass and environment. Our results support the downsizing scenario and the existence of both mass quenching and environmental quenching. The efficiency of mass quenching increases with stellar mass, while environmental quenching is only efficient for low-mass systems. Quenching timescale shows dependence on stellar mass but no clear relation with the environment alone. In the future, we wish to take advantage of Subaru/PFS' large FOV and high efficiency to obtain spectra of our RQG sample and further study the physical mechanisms driving quenching processes.