A&A 474, 375-384 (2007)
DOI: 10.1051/0004-6361:20077542

An approximate theory for substructure propagation in clusters

D. A. Prokhorov^{1, 2} and F. Durret<sup>1

1</sup>  Institut d'Astrophysique de Paris, CNRS, UMR 7095, Université Pierre et Marie Curie, 98bis Bd Arago, 75014 Paris, France
    e-mail: prokhoro@iap.fr
²  Moscow Institute of Physics and Technology, Institutskii lane, 141700 Moscow Region, Dolgoprudnii, Russia

(Received 26 March 2007 / Accepted 2 August 2007)

Abstract
Aims.The existence of dark matter can be proved in an astrophysical context by the discovery of a system in which the observed baryons and the inferred dark matter are spatially segregated, such as the bullet cluster (1E0657-558). The full descriptions of the dark matter halo and X-ray gas substructure motions are necessary to forecast the location of the dark halo from X-ray maps, which can be confirmed by the detection of a galaxy concentration or by gravitational lensing.
Methods.We present an analytical hydrodynamic model to determine the distance between the X-ray and dark-matter components and the Mach number of the merger shock.
Results.An approximate solution is given for the problem of the substructure propagation in merging clusters. A new method to predict the position of a dark matter halo in clusters, where there is a separation between the X-ray gas and the dark halo, is proposed and applied to the clusters 1E0657-558 and Abell 1763.

Key words: galaxies: clusters: general -- galaxies: clusters: individual: 1E0657-558 -- galaxies: clusters: individual: Abell 1763 -- intergalactic medium -- shock waves -- X-rays: galaxies: clusters

© ESO 2007

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