MASS SEGREGATION IN DARK-MATTER MODELS

We use the moments of counts of neighbors as given by the generalized correlation integrals, to study the clustering properties of dark matter halos (DHs) in cold dark matter (CDM) and cold+hot dark matter (CHDM) models. We compare the results with those found in the CfA and SSRS galaxy catalogs. We show that if we apply the analysis in redshift space, both models reproduce equally well the observed clustering of galaxies. Mass segregation is also found in the models: more massive DHs are more clustered compared with less massive ones. For example, at 3h(-1) Mpc in real space, the number of neighbors in excess of random increases similar to 3 times when the mass of halos increases by similar to 100. In redshift space, this mass segregation is reduced by a factor similar to 2-3 due to the peculiar velocities. Observational catalogs give an indication of luminosity and size segregation, which is consistent with the predictions of the models. Because the mass segregation is smaller in redshift space, it is suggestive that the real luminosity or size segregation of galaxies could be significantly larger than what it is found in redshift catalogs.