Study of the Structure of the Coma Cluster Based on a Hierarchical Powerful Clustering Method

Abstract

Six subclusters in the Coma cluster have been selected on the basis of a hierarchical clustering method that takes the gravitational interaction among galaxies into account. Of these, three main subclusters around the galaxies NGC 4889, NGC 4874, and NGC 4839 have been singled out. We have used the objective statistical criterion applied by Vennik and Anosova in studies of close groups of galaxies to evaluate each member included in a subcluster with a high probability. Galaxies with a significant deficit of hydrogen HI, including objects from the Bravo-Alfaro list,have been identified with members of the subclusters, with the greatest number of them in the subclusters around NGC 4874 and NGC 4839. A quantitative estimate of the hydrogen deficit using the HI index in the RCG3 catalog reveals a statistically significant excess value for those galaxies that are members of the subclusters compared to the field galaxies with a hydrogen deficit in the studied area of Coma cluster. A substantial number of the spiral galaxies with a hydrogen deficit in the subclusters turned out to be radio galaxies as well.Comment: This is a revised version of the paper, published in "Astrophysics",vol.48, no 4, 200