Quenching low-mass satellite galaxies: evidence for a threshold ICM density.
ROBERTS I.D., PARKER L.C., BROWN T., JOSHI G.D., HLAVACEK-LARRONDO J. and WADSLEY J.
Abstract (from CDS):
We compile a sample of Sloan Digital Sky Survey (SDSS) galaxy clusters with high-quality Chandra X-ray data to directly study the influence of the dense intracluster medium (ICM) on the quenching of satellite galaxies. We study the quenched fractions of satellite galaxies as a function of ICM density for low- (109 <= M* <= 1010 M☉), intermediate- (1010 <= M* <= 1010.5 M☉), and high-mass (M* >= 1010.5 M☉) satellite galaxies with >3000 satellite galaxies across 24 low-redshift (z < 0.1) clusters. For low-mass galaxies we find evidence for a broken power-law trend between satellite quenched fraction and local ICM density. The quenched fraction increases modestly at ICM densities below a threshold before increasing sharply beyond this threshold toward the cluster center. We show that this increase in quenched fraction at high ICM density is well matched by a simple, analytic model of ram pressure stripping. These results are consistent with a picture where low-mass cluster galaxies experience an initial, slow-quenching mode driven by steady gas depletion, followed by rapid quenching associated with ram pressure of cold-gas stripping near (one-quarter of the virial radius, on average) the cluster center.