OMEGA - OSIRIS Mapping of Emission-line Galaxies in A901/2: III. -
  Galaxy Properties Across Projected Phase Space in A901/2
  We conduct a comprehensive projected phase-space analysis of the A901/2
multi-cluster system at $z\sim0.165$. Aggregating redshifts from spectroscopy,
tunable-filter imaging, and prism techniques, we assemble a sample of 856
cluster galaxies reaching $10^{8.5}M_\odot$ in stellar mass. We look for
variations in cluster galaxy properties between virialised and non-virialised
regions of projected phase-space (PPS). Our main conclusions point to
relatively gentle environmental effects, expressed mainly on galaxy gas
reservoirs. (1) Stacking the four subclusters in A901/2, we find galaxies in
the virialised region are more massive, redder, and have marginally higher
S\`ersic indices, but their half-light radii and Hubble types are not
significantly different. (2) After accounting for trends in stellar mass, there
is a remaining change in rest-frame colour across PPS. Primarily, the colour
difference is due to an absence in the virialised region of galaxies with
rest-frame $B-V<0.7$ and moderate-to-high ($M_\star>10^{9.85}M_\odot$) stellar
mass. (3) There is an infalling population of lower-mass
($M_\star\leq10^{9.85}M_\odot$), relatively blue ($B-V<0.7$) elliptical or
spheroidal galaxies that is strikingly absent in the virialised region. (4) The
number of bona-fide star-forming and AGN galaxies in the PPS regions is
strongly dictated by stellar mass. However, there remains a reduced fraction of
star-forming galaxies in the centres of the clusters at fixed stellar mass,
consistent with the star-formation-density relation in galaxy clusters. (5)
There is no change in specific H$\alpha$-derived star-formation rates of
star-forming galaxies at fixed mass across the cluster environment. This
suggests that preprocessing of galaxies during infall plays a prominent role in
quenching star formation.
