The Early-Type Dwarf-to-Giant Ratio and Substructure in the Coma Cluster
Abstract
We have obtained new CCD photometry for a sample of ~800 early-type galaxies (dwarf and giant ellipticals) in the central 700 arcmin^2^ of the Coma cluster, complete in color and in magnitude to R = 22.5 mag (M_R_ ~ -12 mag for H_0_ = 86 km s^-1^ Mpc^-1^). The composite luminosity function for all galaxies in the cluster core (excluding NGC 4874 and NGC 4889) is modeled as the sum of a Gaussian distribution for the giant galaxies and a Schechter function for the dwarf elliptical galaxies. We determine that the early-type dwarf-to-giant ratio (EDGR) for Coma is identical to that measured for the less rich Virgo cluster; i.e., the EDGR does not increase as predicted by the EDGR-richness correlation. We postulate that the presence of substructure is an important factor in determining the cluster's EDGR; that is, the EDGR for Coma is consistent with the Coma cluster being built up from the merger of multiple less- rich galaxy clusters.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 1996
- DOI:
- 10.1086/177810
- arXiv:
- arXiv:astro-ph/9605093
- Bibcode:
- 1996ApJ...469..623S
- Keywords:
-
- GALAXIES: CLUSTERS: INDIVIDUAL NAME: COMA;
- GALAXIES: EVOLUTION;
- GALAXIES: FORMATION;
- GALAXIES: LUMINOSITY FUNCTION;
- MASS FUNCTION;
- Astrophysics
- E-Print:
- 13 pages, LaTeX file, 3 EPS figures, uses aaspp4.sty