A Comparison of Surface Brightness Profiles for Ultracompact Dwarfs and Dwarf Elliptical Nuclei: Implications for the "Threshing" Scenario

Publisher Website
Google Scholar
Abstract
Using imaging from the Hubble Space Telescope, we derive surface brightness profiles for ultra-compact dwarfs in the Fornax cluster and for the nuclei of dwarf elliptical galaxies in the Virgo cluster. Ultra-compact dwarfs are more extended and have higher surface brightnesses than typical dwarf nuclei, while the luminosities, colors, and sizes of the nuclei are closer to those of Galactic globular clusters. This calls into question the production of ultra-compact dwarfs via ``threshing'' whereby the lower surface brightness envelope of a dwarf elliptical is removed by tidal processes, leaving behind a bare nucleus. Threshing may still be a viable model if the relatively bright Fornax ultra compact dwarfs considered here are descended from dwarf ellipticals whose nuclei are at the upper end of their luminosity and size distributions.Comment: 5 pages, 2 figures, 1 table, uses emulateapj.cls (included) ApJ Letters, accepted for publicatio
All Related Versions