Galaxy mass, cluster-centric distance and secular evolution: their role in the evolution of galaxies in clusters in the last 10 Gyr

Context. Galaxy mass and environment are known to play a key role in galaxy evolution: studying galaxy colors as a function of redshift, galaxy mass, and environment offers a powerful diagnosis to disentangle the role of each. Aims. We study the simultaneous dependence of the fraction of blue galaxies f(blue) on secular evolution, environment, and galaxy mass with a well-controlled cluster sample. We are thus able to study the evolution and respective role of the cessation of star formation history (SFH) in clusters caused by galaxy mass (mass quenching) or by environment (environmental quenching). Methods. We defined an homogenous X-ray selected cluster sample (25 clusters with 0 < z < 1 and one cluster at z similar to 2.2), having similar masses and well-defined sizes. Using multicolor photometry and a large spectroscopic sample to calibrate photometric redshifts, we carefully estimated f(blue) for each cluster at different galaxy mass and cluster-centric distance bins. We then fitted the dependence of f(blue) on redshift (z), environment (r/r(200)) and galaxy mass (M) with a simple model. Results. f(blue) increases with cluster-centric distance with a slope alpha = 1.2(-0.3)(+0.4), decreases with galaxy mass with a slope beta = -3.8(-0.5)(+0.6), and increases with redshift with a slope gamma = 3.3(-0.6)(+0.7). The data also require for the first time a differential evolution with galaxy mass of f(blue) with redshift, with lower mass galaxies evolving slower by a factor zeta = -3.9(-1.1)(+0.9). Conclusions. Our study shows that the processes responsible for the cessation of star formation in clusters are effective at all epochs (z less than or similar to 2.2), and more effective in denser environments and for more massive galaxies. We found that the mass and environmental quenchings are separable, that environmental quenching does not change with epoch, and that mass quenching is a dynamical process, i.e. its evolutionary rate is mass-dependent. Our study extends the downsizing-like scenario, where the most massive galaxies have their properties set at a very high redshift, to the cluster environment and all galaxies. It illustrates the need to disentangle galaxy mass and cluster-centric distance to properly estimate the behavior of f(blue) in clusters.