The Role of Ram Pressure Stripping in the Quenching of Cluster Star
  Formation
  Recent observations of galaxy clusters have shown that environmental effects
apparently associated with the cluster begin to lower the star formation rates
of galaxies at distances as great as three times the cluster virial radius.
These observations may indicate preprocessing of cluster galaxies in groups or
in the cluster core for galaxies on highly elliptical orbits, but may also
imply that the environmental effects due to the cluster are directly affecting
galaxies on their first infall. To explore these issues, we investigate
different models of ram pressure stripping as it acts on satellite galaxies in
clusters, and compare to observations of the radial star formation gradient in
clusters. We calculate the location of the accretion shock around model
clusters, and use this as the radius of onset of ram pressure stripping in the
GALFORM semi-analytic model of galaxy formation. Comparison of the results of
our model, and previously considered, simpler ram pressure models, with recent
observations indicates that current data is unable to strongly discriminate
between models of ram pressure stripping due to the complex interplay of
preprocessing effects at work. However, future observations of a larger sample
of clusters will likely be able to place stronger constraints on the process of
ram pressure stripping and its role in shaping radial trends in and around
clusters.
