A Multiband Study of the Galaxy Populations of the First Four
  Sunyaev--Zeldovich Effect selected Galaxy Clusters
  We present first results of an examination of the optical properties of the
galaxy populations in SZE selected galaxy clusters. Using clusters selected by
the South Pole Telescope survey and deep multiband optical data from the Blanco
Cosmology Survey, we measure the radial profile, the luminosity function, the
blue fraction and the halo occupation number of the galaxy populations of these
four clusters with redshifts ranging from 0.3 to 1. Our goal is to understand
whether there are differences among the galaxy populations of these SZE
selected clusters and previously studied clusters selected in the optical and
the X-ray. The radial distributions of galaxies in the four systems are
consistent with NFW profiles with a galaxy concentration of 3 to 6. We show
that the characteristic luminosities in $griz$ bands are consistent with
passively evolving populations emerging from a single burst at redshift $z=3$.
The faint end power law slope of the luminosity function is found to be on
average $\alpha \approx -1.2$ in griz. Halo occupation numbers (to $m^*+2$) for
these systems appear to be consistent with those based on X-ray selected
clusters. The blue fraction estimated to $0.36L^*$, for the three lower
redshift systems, suggests an increase with redshift, although with the current
sample the uncertainties are still large. Overall, this pilot study of the
first four clusters provides no evidence that the galaxy populations in these
systems differ significantly from those in previously studied cluster
populations selected in the X-ray or the optical.
