Galaxies and Dark Matter in Groups
This thesis presents a systematic study of the relationships between galaxy properties and their environments. Multi-wavelength imaging and spectroscopic data are used to construct a large sample of galaxy groups spanning nearly half the age of the Universe. Weak gravitational lensing measurements enable a census of baryonic and dark matter in these groups, and in particular, identification of halo centers. With empirically determined centers of mass, trends in galaxy colors and morphologies with groupcentric distance are studied to test models of galaxy evolution.