The Evolution of Dusty Star formation in Galaxy Clusters to z = 1:
  Spitzer IR Observations of the First Red-Sequence Cluster Survey
  We present an IR study of high-redshift galaxy clusters with the MIPS camera
on the Spitzer Space Telescope. Employing a sample of 42 clusters from the
RCS-1 over the redshift range 0.3 < z < 1.0 and spanning an approximate range
in mass of 10^{14-15} Msun, we show the number of IR-luminous galaxies in
clusters above a fixed IR luminosity of 2x10^{11} Msun per unit cluster mass
evolves as (1+z)^{5.1+/-1.9}. These results assume a single star forming galaxy
template; the presence of AGN, and an evolution in their relative contribution
to the mid-IR galaxy emission, will alter the overall number counts per cluster
and their rate of evolution. We infer the total SFR per unit cluster mass and
find T_SFR/M_c ~ (1+z)^{5.4+/-1.9}. This evolution can be attributed entirely
to the change in the in-falling field galaxy population. The T_SFR/M_c (binned
over all redshift) decreases with increasing cluster mass with a slope
(T_SFR/M_c ~ M_c^{-1.5+/-0.4}) consistent with the dependence of the
stellar-to-total mass per unit cluster mass seen locally. The inferred star
formation seen here could produce ~5-10% of the total stellar mass in massive
clusters at z = 0. Finally, we show a clear decrease in the number of IR-bright
galaxies per unit optical galaxy in the cluster cores, confirming star
formation continues to avoid the highest density regions of the universe at z ~
0.75 (the average redshift of the high-redshift clusters). While several
previous studies appear to show enhanced star formation in high-redshift
clusters relative to the field we note that these papers have not accounted for
the overall increase in galaxy or dark matter density at the location of
clusters. Once this is done, clusters at z ~ 0.75 have the same or less star
formation per unit mass or galaxy as the field.
