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Session 123 - Galaxy Evolution: Dwarfs & Clusters.
Oral session, Saturday, January 10

[123.02] Dwarf Galaxies and Their Formation: A Study in the Compact Group Environment

S. D. Hunsberger (PSU)

From R-band images of 39 Hickson compact groups (HCGs), we use galaxy counts within the regions of compact groups to determine a luminosity function extending to M_R=-14.5 + 5\log h_75, at least 11 øver 2 magnitudes deeper than previous compact group luminosity functions. We fit the bright and faint galaxies separately with two Schechter functions. The bright end is best fit with M=-21.7 and \alpha=-0.56 and the faint end with M^*=-16.0 and \alpha=-1.07. The decreasing bright end slope hints at a deficit of bright dwarfs in our sample of HCGs and the faint end slope is similar to that reported for earlier HCG luminosity functions. However, luminosity functions of subsets of our sample reveal larger dwarf populations for groups with x-ray halos, groups with tidal tails/arms, and groups with dominant elliptical or lenticular galaxies. For groups without x-ray halos, those with high M/L have a small dwarf population compared to those with low M/L. These data support the hypothesis that the initial dwarf galaxy population is replenished by ``subsequent generations'' formed in the tidal debris of giant galaxy interactions.

Program listing for Saturday