Do star formation rates of galaxy clusters depend on mass?:   blue/late-type fractions, total star formation rates of 115 galaxy clusters   as a function of cluster virial mass
  There has been plenty of observational evidence of cluster galaxy evolution such as the Butcher-Oemler effect and the decrease in S0 fraction with increasing redshift. As a modern version, the redshift evolution of total star formation rate (SFR) in clusters has been actively debated recently. However, these studies of redshift trend have been always hampered by the possible mass dependence; due to the observational selection effects, clusters found at higher redshift inevitably tend to be more massive and luminous than local counterparts. Consequently, one has to correct for the mass trend before interpreting the redshift trend.   As an attempt to break this degeneracy, we investigate the mass dependence of blue/late-type fractions and total SFR of 115 clusters at $z\leq 0.09$ selected from the Sloan Digital Sky Survey. We find that none of blue/late-type fractions, total SFR and total SFR normalized by cluster mass shows significant dependence on cluster virial mass. The scatter is much larger at each cluster mass than a possible trend. Our results indicates that physical mechanisms that depend on cluster mass (such as the ram-pressure stripping) are not likely to be solely responsible for cluster galaxy evolution. Our results also provide an excellent low redshift comparison sample for future high redshift cluster SFR studies. 
Tomotsugu Goto (JHU)