Anisotropies in the redshift-space correlations of galaxy groups and clusters II: Analysis of observational cluster samples

We study the redshift space correlation function of galaxy clusters for observational samples constructed in different surveys. We explore correlation amplitudes, pairwise velocity distributions and bias factors. Systematics in cluster identification procedures are the main source of biased estimates of the correlation amplitude and inferred velocity dispersions. By comparing our results with those of numerical simulations we explore the strong influence on the clustering distortion pattern in redshift space from effects associated with the cluster identification procedure from two dimensional surveys as is the case of Abell and APM clusters. The identification of clusters in X-ray surveys improves this situation, although there are still systematic effects which are probably due to identification of optical sources in the determination of cluster redshifts. These systematics are particularly strong for the most luminous X-ray selected clusters in the Extended Bright Cluster Survey, which exhibits very large anisotropies, comparable to those present in the Abell catalogue. Our results demonstrate that forthcoming large redshift surveys will be extremely important for the construction of new samples of groups and clusters as well as improving the determination of optical and X-ray selected cluster distances, essential for reliable analyses of the large scale structure.