The Morphology Dependence of Luminosity Segregation in the Coma Cluster

We carry out CCD photometry of galaxies in the 5.25 deg2 region centered on the Coma Cluster down to MR = -16.0, which is beyond the limit of conventional morphological classification. We use the angular two-point correlation function as well as radial profiles in order to characterize the luminosity segregation. We find strong luminosity segregation for our total sample over the magnitude range of -20 ≤ MR ≤ -16, which is not entirely accounted for in terms of the morphology-density relation that is known to exist only for bright galaxies. We use a single consistent parameter, the degree of luminosity concentration, to parameterize the morphology of galaxies over the wide magnitude range, where both giant and dwarf galaxies are included. Galaxies with high central concentration (HCC) show strong luminosity segregation, i.e., their clustering strength depends strongly on luminosity, while those with low central concentration (LCC) show almost no luminosity segregation. The radial density profiles show that brighter HCC-type galaxies tend to more strongly concentrate near the cluster center, while LCC-type galaxies do not show such a dependence on luminosity. We show that these results are tenable against the contamination by field galaxies and uncertainties in our method of classification.