ar X iv : a st ro - p h / 01 11 03 8 v 1 2 N ov 2 00 1 Substructure in the Coma Cluster : Giants vs Dwarfs

The processes that form and shape galaxy clusters, such as infall, mergers and dynamical relaxation, tend to generate distinguishable differences between the distributions of a cluster’s giant and dwarf galaxies. Thus the dynamics of dwarf galaxies in a cluster can provide valuable insights into its dynamical history. With this in mind, we look for differences between the spatial and velocity distributions of giant (b< 18) and dwarf (b> 18) galaxies in the Coma cluster. Our redshift sample contains new measurements from the 2dF and WYFFOS spectrographs, making it more complete at faint magnitudes than any previously studied sample of Coma galaxies. It includes 745 cluster members – 452 giants and 293 dwarfs. We find that the line-of-sight velocity distribution of the giants is significantly non-Gaussian, but not that for the dwarfs. A battery of statistical Correspondence to: [email protected] Also affiliated with the Space Sciences Department of the European Space Agency