Two Updates on Galaxy Clusters: the Halo Virial Scaling Relation 
 and Red Sequence Cluster Finding

 August  Evrard
 Departments of Physics and Astronomy
 Michigan Center for Theoretical Physics
 University of Michigan

 Abstract.  Clusters of galaxies are attractive to both 
 cosmologists, who think of them as a regular family of dark matter 
 halos, and astrophysicists, who consider them rare locations where 
 messy, coupled processes drive baryonic evolution.  This talk will 
 use two recent projects to illustrate both viewpoints, ending with 
 a perspective on how to reconcile them.