EDP Sciences
Free access
Volume 386, Number 3, May II 2002
Page(s) 816 - 828
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20020244

A&A 386, 816-828 (2002)
DOI: 10.1051/0004-6361:20020244

The dynamical status of the cluster of galaxies 1E0657-56

R. Barrena1, A. Biviano2, M. Ramella2, E. E. Falco3 and S. Seitz4

1  Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
2  INAF, Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, 34131 Trieste, Italy
3  Smithsonian Institution, F. L. Whipple Observatory, PO Box 97, 670 Mount Hopkins, Amado, AZ 85645, USA
4  Universitäts-Sternwarte, Scheinerstrasse 1, 81679 Muenchen, Germany

(Received 19 December 2001 / Accepted 12 February 2002 )

We present the results of a new spectroscopic and photometric survey of the hot X-ray cluster , at z=0.296. We determine the presence of a low velocity dispersion subcluster, which is offset from the main cluster position by 0.7 Mpc and $\simeq $600 km s -1. We determine the virial masses and total luminosities of the cluster and its subcluster, and solve for the two-body dynamical model. With additional constraints from the results of the analysis of the cluster X-ray emission by Markevitch et al. (2001), we find that the subcluster passed through the cluster centre $\simeq $0.15 Gyr ago. Taken at face value the mass of the subcluster is typical of a loose group. It is however difficult to establish the pre-merger mass of the colliding system. We provide tentative evidence that the subcluster is in fact the remnant core of a moderately massive cluster, stripped by the collision with . The main cluster dynamics does not seem to have suffered from this collision. On the contrary, the cluster X-ray properties seem to have been significantly affected. We also discuss the effect of the subcluster collision in relation to starburst events and the cluster radio halo.

Key words: galaxies: clusters: individual: 1E0657-56 -- galaxies: clusters: general -- galaxies: distances and redshifts

Offprint request: A. Biviano, biviano@ts.astro.it

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