Galaxy morphological segregation in clusters:: Local versus global conditions

We study the relative fraction of galaxy morphological types in clusters as a function of the projected local galaxy density and of different global parameters: cluster projected gas density, cluster projected total mass density, and reduced cluster-centric distance. Since local and global densities are correlated, we have considered different tests to search for the parameters on which segregation shows the strongest dependence. We have also explored the results of our analysis as they apply to both the central regions of the clusters and their outskirts. We consider a sample of clusters of galaxies with estimated temperatures and derive the projected mass density profile, using the model of Navarro, Frenk, & White, and the 500 overdensity contrast radius (r(500)), using the scaling relation. X-ray surface brightness profiles are used to obtain the projected gas density, assuming the hydrostatic equilibrium model. Our results suggest that morphological segregation in clusters is controlled by local galaxy density in the outskirts. On the other hand, global projected mass density shows the strongest correlation with the fractions of morphological types in the central high-density region, with a marginal dependence on local galaxy density.