Unveiling hidden structures in the coma cluster

• Type: Article in International Scientific Journal
• Date: 1996

Authors

Biviano, A (Author) Other; Durret, F (Author) Other; Gerbal, D (Author) Other; LeFevre, O (Author) Other; Lobo, C (Author) Other; Mazure, A (Author) Other; Slezak, E (Author) Other

Journal

Title: Astronomy and Astrophysics

Vol. 311

Pages: 95-112

ISSN: 0004-6361

Publisher: EDP Sciences

Indexing

ISI Web of Knowledge - 108 Citations

Scopus - 99 Citations

Scientific classification

FOS: Natural sciences > Physical sciences

Other information

Authenticus ID: P-001-E0Z

Abstract (EN): We have assembled a large data-set of 613 galaxy redshifts in the Coma cluster, the largest presently available for a cluster of galaxies. We have defined a sample of cluster members complete to b(26.5) = 20.0, using a membership criterion based on the galaxy velocity, when available, or on the galaxy magnitude and colour, otherwise. Such a data set allows us to define nearly complete samples within a region of 1 h(-1) Mpc radius, with a sufficient number of galaxies per sample to make statistical analyses possible. Using this sample and the ROSAT PSPC X-ray image of the cluster, we have re-analyzed the structure and kinematics of Coma, by applying the wavelet and adaptive kernel techniques. A striking coincidence of features is found in the distributions of galaxies and hot intracluster gas. The two central dominant galaxies, NGC 4874 and NGC 4889, are surrounded by two galaxy groups, mostly populated with galaxies brighter than b(26.5) = 17 and well separated in velocity space. On the contrary, the fainter galaxies tend to form a single smooth structure with a central peak coinciding in position with a secondary peak detected in X-rays, and located between the two dominant galaxies; we suggest to identify this structure with the main body of the Coma cluster. A continuous velocity gradient is found in the central distribution of these faint galaxies, a probable signature of tidal interactions rather than rotation. There is evidence for a bound population of bright galaxies around other brightest cluster members. Altogether, the Coma cluster structure seems to be better traced by the faint galaxy population, the bright galaxies being located in subclusters. We discuss this evidence in terms of an ongoing accretion of groups onto the cluster.

Language: English

Type (Professor's evaluation): Scientific