The A2197 and A2199 galaxy clusters

Abstract

New redshifts are presented for 74 galaxies in and near the rich clusters A2197 and A2199. When added to results in the literature, the authors have a total sample of 136 galaxies with known redshifts in the region. They determine the systematic redshift and line-of-sight velocity dispersions for both clusters. By applying the virial theorem they find mass-to-light (M/L) ratios for each cluster core in the range 200 - 400. The authors model the binary cluster with a two-body infall analysis and thereby determine an independent estimate for the M/L ratio of the entire system. Surprisingly, the double cluster method indicates that M/L < 100.