Globular Cluster Systems of Early-Type Galaxies as probes of galaxy evolution (Maren Hempel, DAA PUC)

Early-type galaxies are the most massive stellar systems in the Universe and their formation must follow directly from any cosmological model. In order to put galaxy formation in a cosmological context we need to know when and how those galaxies form the majority of their stars. Despite the fact that early-type galaxies seem to be rather simple stellar structures deriving the age and metallicity of the stellar populations turns out to be quite challenging. Globular clusters are frequently used to resolve stellar populations in distant galaxies and their colors and/or spectral indices allow us to set constrains on the major star formation episodes in their host galaxies. However, the increasing amount of data on early-type galaxies have shown that those relatively 'simple' systems may be far more diverse then previously thought. I will present the results of our ongoing photometric study of early-type galaxies and their globular cluster systems with respect to the age structure and how it is connected to various galaxy properties.