The distribution of cluster members in the vicinity of a central dominant galaxy

The projected distribution of cluster members within 250/h kpc of a central dominant galaxy is determined based upon CCD images of 29 galactic clusters. It is found that the radial distribution of the projected galaxy number density is well described by an exponential profile with an e-folding length of about 100/h kpc. The dynamics of the projected profile are studied for a range of possible mass distributions, and existing redshift data are found to be consistent with an isotropic velocity distribution. It is suggested that the high central density associated with this cusped distribution may explain the presence of at least 50 percent of the observed multiple nuclei projected within 10/h kpc of the center of the dominant galaxy. It is noted that the high densities and low velocities of galaxies in the cluster core may lead to a sufficiently high rate of collisions between cluster members and the central dominant galaxy to produce a significant population of multiple nuclei which are in the process of merging with the underlying central galaxy. 42 refs