The angular cross-correlation function in clusters of galaxies

Abstract

We analyze angular cross-correlation functions between distance classes D=1-4 and D=6 of Abell and ACO catalogs of rich clusters of galaxies and we study the dependence of these correlations on cluster richness. We find that anticorrelations are present in the rich sample R ≥ 1 of ACO catalog, similar to that obtained by Szalay et al. in Abell catalog. However, the anticorrelations vanish for the sample of nearby poor clusters R=0, D=1-4 vs R ≥ 1, D=6 in both catalogs. We apply the decontamination process discussed by Dekel et al. and Olivier et al., and we analyze similar cross-correlation in the decontaminated catalogs. The results indicate that the decontamination catalogs. We apply the decontamination process discussed by Dekel et al. and Olivier et al., and we analyze similar cross-correlations in the decontaminated catalogs. The results indicate that the decontamination process does not change the systematic found in the cross-correlation functions of original catalogs. We perform several statistical analyzes in order to investigate the possibility that combined effects of Abell radius and the clustering of nearby clusters, and a bias in the assignment of distances may have contributed to enhancement of the anti-correlations.