Interpreting the Clustering of Distant Red Galaxies
  We analyze the angular clustering of z~2.3 distant red galaxies (DRGs)
measured by Quadri et al 2008. We find that, with robust estimates of the
measurement errors and realistic halo occupation distribution modeling, the
measured clustering can be well fit within standard halo occupation models, in
contrast to previous results. However, in order to fit the strong break in
w(theta) at theta=10 arcsec, nearly all satellite galaxies in the DRG
luminosity range are required to be DRGs. Within this luminosity-threshold
sample, the fraction of galaxies that are DRGs is ~44%, implying that the
formation of DRGs is more efficient for satellite galaxies than for central
galaxies. Despite the evolved stellar populations contained within DRGs at
z=2.3, 90% of satellite galaxies in the DRG luminosity range have been accreted
within 500 Myr. Thus, satellite DRGs must have known they would become
satellites well before the time of their accretion. This implies that the
formation of DRGs correlates with large-scale environment at fixed halo mass,
although the large-scale bias of DRGs can be well fit without such assumptions.
Further data are required to resolve this issue. Using the observational
estimate that ~30% of DRGs have no ongoing star formation, we infer a timescale
for star formation quenching for satellite galaxies of 450 Myr, although the
uncertainty on this number is large. However, unless all non-star forming
satellite DRGs were quenched before accretion, the quenching timescale is
significantly shorter than z~0 estimates. Down to the completeness limit of the
Quadri et al sample, we find that the halo masses of central DRGs are ~50%
higher than non-DRGs in the same luminosity range, but at the highest halo
masses the central galaxies are DRGs only ~2/3 of the time.
