Statistical analysis of bound companions in the Coma cluster

Abstract

The rich and nearby Coma cluster of galaxies is known to have substructure. We aim to create a more detailed picture of this substructure by searching directly for bound companions around individual giant members. We have used two catalogs of Coma galaxies, one covering the cluster core for a detailed morphological analysis, another covering the outskirts. The separation limit between possible companions (secondaries) and giants (primaries) is chosen as M_B = -19 and M_R = -20, respectively for the two catalogs. We have created pseudo-clusters by shuffling positions or velocities of the primaries and search for significant over-densities of possible companions around giants by comparison with the data. This method was developed and applied first to the Virgo cluster by Ferguson (1992). In a second approach we introduced a modified nearest neighbor analysis using several interaction parameters for all galaxies. We find evidence for some excesses due to possible companions for both catalogs. Satellites are typically found among the faintest dwarfs (M_B < -16) around high-luminosity primaries. The most significant excesses are found around very luminous late-type giants (spirals) in the outskirts, which is expected in an infall scenario of cluster evolution. A rough estimate for an upper limit of bound galaxies within Coma is 2 - 4 percent, to be compared with ca. 7 percent for Virgo. The results agree well with the expected low frequency of bound companions in a regular cluster such as Coma.

arXiv commentAstronomy & Astrophysics, in press; 17 pages, 13 figures

References in corpus (25)

• The Seventh Data Release of the Sloan Digital Sky Survey
• Environmental Effects on Late-Type Galaxies in Nearby Clusters
• Formation of Galaxy Clusters
• Structure and Dynamics of the Coma Cluster
• Dark matter distribution in the Coma cluster from galaxy kinematics: breaking the mass-anisotropy degeneracy
• The Local Group and other neighboring galaxy groups
• The Luminosity Function of the Coma Cluster Core for -25<M_R<-11
• The dynamical state of the Coma cluster with XMM-Newton
• The build-up of the Coma cluster by infalling substructures
• The NGC4839 group falling into the Coma cluster observed by XMM-Newton
• Dwarf galaxy populations in present-day galaxy clusters: I. Abundances and red fractions
• U, B and r band luminosity functions of galaxies in the Coma cluster
• Dwarf Galaxies in the Coma Cluster. II. Photometry and Analysis
• The dwarf galaxy population of the Coma cluster to M_R=-11
• A photometric and spectroscopic study of dwarf and giant galaxies in the Coma cluster - II. Spectroscopic observations
• Large-Scale Structure Formation: from the first non-linear objects to massive galaxy clusters
• Deep and wide field imaging of the Coma cluster: the data
• The Early-type Dwarf-to-Giant Ratio and Substructure in the Coma Cluster
• Galaxy subgroups in galaxy clusters
• Identification of galaxy cluster substructures with the Caustic method
• Substructure in the Coma Cluster: Giants vs Dwarfs
• Keck/LRIS Spectroscopic Confirmation of Coma Cluster Dwarf Galaxy Membership Assignments
• Morphology of galaxies in the Coma cluster region down to M_B=-14.25. I. A catalog of 473 members
• An Examination of the Optical Substructure of Galaxy Clusters Hosting Radio Sources
• On the nature of faint Low Surface Brightness galaxies in the Coma cluster

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• J-PLUS: analysis of the intracluster light in the Coma cluster
• Origins of ultra-diffuse galaxies in the Coma cluster - I. Constraints from velocity phase-space