  We extend the phenomenological study of the evolving galaxy population of
Peng et al (2010) to the central/satellite dichotomy in Yang et al. SDSS
groups. We find that satellite galaxies are responsible for all the
environmental effects in our earlier work. The fraction of centrals that are
red does not depend on their environment but only on their stellar masses,
whereas that of the satellites depends on both. We define a relative satellite
quenching efficiency, which is the fraction of blue centrals that are quenched
upon becoming the satellite of another galaxy. This is shown to be independent
of stellar mass, but to depend strongly on local overdensity. The red fraction
of satellites correlate much better with the local overdensity, a measure of
location within the group, than with the richness of the group, i.e. dark
matter halo mass. This, and the fact that satellite quenching depends on local
density and not on either the stellar mass of the galaxy or the halo mass gives
clues as to the nature of the satellite-quenching process. We furthermore show
that the action of mass-quenching on satellite galaxies is also independent of
the DM mass of the parent halo. We then apply the Peng et al (2010) approach to
predict the mass functions of central and satellite galaxies, split into
passive and active galaxies, and show that these match very well the observed
mass functions from SDSS, further strengthening the validity of this
phenomenological approach. We highlight the fact that the observed M* is the
same for the star-forming centrals and satellites and the observed M* for the
star-forming satellites is independent of halo mass above 10^12M\odot, which
emphasizes the universality of the mass-quenching process that we identified in
Peng et al (2010). Post-quenching merging modifies the mass function of the
central galaxies but can increase the mass of typical centrals by only about
25%.

Cosmology and Nongalactic Astrophysics