Luminosity Segregation from Merging in Clusters of Galaxies

We compute the evolution of the space-dependent mass distribution of galaxiesin clusters due to binary aggregations by solving a space-dependentSmoluchowski equation. We derive the distribution of intergalactic distance fordifferent ranges of mass (and of corresponding magnitude). We compare theresults with the observed distributions, and find that the different degrees ofluminosity segregation observed in clusters are well accounted for by ourmerging model. In addition, the presence of luminosity segregation is relatedto dynamical effects which also show up in different but connected observables,such as galaxy velocity profiles decreasing toward the center and X-raymeasured beta-parameters smaller than 1. We predict both luminosity segregationand the observables above (being a product of binary aggregations) to beinversely correlated with the core radius and with the galaxy velocitydispersion; we discuss how the whole set of predictions compares withup-to-date observations.Comment: 14 pages, Latex, 6 Figures and 2 Tables in Postscript. To appear in Astrophysical Journal Part