Imaging of extragalactic globular cluster systems

Globular clusters are a class of star cluster notable for their compactness and relatively high total masses. Their formation requires very unique conditions that were more commonplace in the early Universe, thus the study of extragalactic globular cluster systems can yield useful observational constraints on the first stages of galaxy formation. This thesis contains a detailed study of the globular cluster (GC) systems of four galaxies using Hubble Space Telescope, Spitzer Space Telescope and the ground-based WIYN Telescope. The primary results include: Observational evidence that helps to explain the apparent size difference between the globular cluster metallicity subpopulations; The discovery of the first metal-poor GC color-magnitude trend within a spiral galaxy and confirmation that this trend is not caused by a contribution from younger GCs; Mid-IR photometry of two extragalactic GC systems is presented for the first time. This data is used to confirmed GC metallicity bimodality and test stellar population models; The globular cluster system of an elliptical galaxy in an isolated environment is studied. Its properties resemble those found in cluster ellipticals, suggesting galaxy mass was more important in determining globular cluster system numbers compared to the local environment; A direct proportionality between globular cluster system mass and host galaxy dark matter mass is reported; Galaxy bulge formation is constrained in a synthesis of metal-rich globular cluster and galaxy observations from the ACS Virgo Cluster Survey.