The pre-processing of subhaloes in SDSS groups and clusters
  We investigate pre-processing using the observed quenched fraction of group
and cluster galaxies in the Yang et al. (2007) SDSS-DR7 group catalogue in the
redshift range of 0.01 < z < 0.045. We categorize group galaxies as virialized,
infall or backsplash and we apply a combination of the Dressler-Shectman
statistic and group member velocities to identify subhaloes. On average the
fraction of galaxies that reside in subhaloes is a function of host halo mass,
where more massive systems have a higher fraction of subhalo galaxies both in
the overall galaxy and infall populations. Additionally, we find that between 2
< r_200 < 3 the quiescent fraction is higher in the subhalo population with
respect to both the field and non-subhalo populations. At these large radii (2
< r_200 < 3), the majority of galaxies (~ 80 %) belong to the infall population
and therefore, we attribute the enhanced quenching to infalling subhalo
galaxies, indicating that pre-processing has occurred in the subhalo
population. We conclude that pre-processing plays a significant role in the
observed quiescent fraction, but only for the most massive (M_halo > 10^14.5
M_sun) systems in our sample.
