The Specific Globular Cluster Frequencies of Dwarf Elliptical Galaxiesfrom the Hubble Space Telescope

Abstract

The specific globular cluster frequencies (S_N) for 24 dwarf elliptical (dE) galaxies in the Virgo and Fornax Clusters and the Leo Group that were imaged with the Hubble Space Telescope are presented. Combining all available data, we find that for nucleated dE (dE, N) galaxies, which are spatially distributed like giant elliptical galaxies in galaxy clusters, S¯_N(dE, N)=6.5+/-1.2 and S_N increases with M_V, while for nonnucleated dE (dE, noN) galaxies, which are distributed like late-type galaxies, S¯_N(dE, noN)=3.1+/-0.5 and there is little or no trend with M_V. Thus, the S_N values for dE galaxies are, on average, significantly higher than those for late-type galaxies, which have S_N<~1. This suggests that dE galaxies are more akin to giant elliptical galaxies than to late-type galaxies. If there are dormant or stripped irregular galaxies hiding among the dE population, they are likely to be among the nonnucleated dE galaxies. Furthermore, the similarities in the properties of the globular clusters (GCs) and in the spatial distributions of dE, N galaxies and giant elliptical galaxies suggest that neither galaxy mass nor galaxy metallicity is responsible for the high values of S_N. Instead, most metal-poor GCs may have formed in dwarf-sized fragments that merged into larger galaxies.

Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.