IAU Symposium Abstract S186-050T

Globular Clusters in Elliptical Galaxies: Constraints on Mergers

Duncan A. Forbes1
1 Lick Observatory, Santa Cruz, USA (forbes@lick.ucsc.edu)

Globular clusters (GC) are unique probes of the past history of galaxies and as such can be used to place constraints on the role of mergers and galaxy evolution in general. Recent work has shown that giant ellipticals have two populations of GCs; one metal-poor and one metal-rich. This effectively rules out a monolithic collapse model for galaxy formation. We critically review models for GC formation, including the expectations from a merger. We conclude that mergers are unlikely to account for the GCs in giant ellipticals, whereas a multiphase collapse and stripping of GCs via tidal interaction seem viable. Small ellipticals, on the other hand, appear to have a single uniform population of GCs. If these galaxies are the result of a gaseous merger of two spirals, the lack of two populations is a mystery. We discuss several solutions to this problem, the most intriguing of which is that current-day spiral mergers form a new class of elliptical galaxy.