Luminosity segregation as an indication of dynamical evolution in rich clusters of galaxies

The luminosity segregation in several galaxy clusters has been analyzed by means of the intergalactic distance distribution function, corrected from the masking effects of field galaxies. It has been found that the clusters present a gradation of luminosity segregation, from highly segregated to virtually not segregated. In order to understand these results, simulations of the dynamical evolution of galaxy clusters have been carried out by means of the Fokker-Planck equation moments method. It is concluded that the observed mass segregation could be due to dynamical evolution during the two-body relaxation phase, and that their different degrees could be a reflection of either the different initial conditions present at the onset of this phase or different cluster ages. 65 refs