CLASH-VLT: Environment-driven evolution of galaxies in the z=0.209
  cluster Abell 209
  The analysis of galaxy properties and the relations among them and the
environment, can be used to investigate the physical processes driving galaxy
evolution. We study the cluster A209 by using the CLASH-VLT spectroscopic data
combined with Subaru photometry, yielding to 1916 cluster members down to a
stellar mass of 10^{8.6} Msun. We determine: i) the stellar mass function of
star-forming and passive galaxies; ii) the intra-cluster light and its
properties; iii) the orbits of low- and high-mass passive galaxies; and iv) the
mass-size relation of ETGs. The stellar mass function of the star-forming
galaxies does not depend on the environment, while the slope found for passive
galaxies becomes flatter in the densest region. The color distribution of the
intra-cluster light is consistent with the color of passive members. The
analysis of the dynamical orbits shows that low-mass passive galaxies have
tangential orbits, avoiding small pericenters around the BCG. The mass-size
relation of low-mass passive ETGs is flatter than that of high mass galaxies,
and its slope is consistent with that of field star-forming galaxies. Low-mass
galaxies are also more compact within the scale radius of 0.65 Mpc. The ratio
between stellar and number density profiles shows a mass segregation in the
center. The comparative analysis of the stellar and total density profiles
indicates that this effect is due to dynamical friction. Our results are
consistent with a scenario in which the "environmental quenching" of low-mass
galaxies is due to mechanisms such as harassment out to R200, starvation and
ram-pressure stripping at smaller radii, as supported by the analysis of the
mass function, of the dynamical orbits and of the mass-size relation of passive
early-types in different regions. Our analyses support the idea that the
intra-cluster light is formed through the tidal disruption of subgiant
galaxies.
