It has long been known that galaxies in clusters are more likely to be of early type and to have lower star formation rates than galaxies in the field. Over the past decade observations have shown that these effects extend well beyond the cluster virial radius, suggesting that galaxies may have been pre-processed, perhaps by group or filament environments, before they fall into clusters. Studies have also shown that galaxies that fall into a cluster as part of a larger group can stay coherent for up to one orbital period, suggesting the possibility of intra-group interactions within a cluster contributing to the evolution of galaxies in clusters (post-processing). I will talk about the dynamics of group-cluster mergers. In particular, I will talk about how a tidally stripped group stays coherent in velocity space. I will also talk about how galaxy-galaxy interaction rates depend on the environment they live in, i.e., groups and clusters, and how group-cluster mergers affect these interactions.
address: Department of Astronomy, MC-221, 1002 W. Green Street, Urbana, IL 61801 phone: (217) 333-3090 • fax: (217) 244-7638 • email:email@example.com