A cluster in a crowded environment: XMM-Newton and Chandra observations of A3558^*

¹ Università degli Studi di Milano, Dip. di Fisica, via Celoria 16 20133 Milano, Italy
² INAF – Istituto di Astrofisica Spaziale e Fisica Cosmica Milano, via Bassini 15, 20133 Milano, Italy e-mail: rossetti@iasf-milano.inaf.it; silvano@iasf-milano.inaf.it
³ Max Planck Institut fur extraterrestrische Physik, 85748 Garching, Germany

Received: 1 December 2005
Accepted: 12 October 2006

Abstract

Combining XMM-Newton and Chandra data, we have performed a detailed study of Abell 3558. Our analysis shows that its dynamical history is more complicated than previously thought. We have found some traits typical of cool core clusters (surface brightness peaked at the center, peaked metal abundance profile) and others that are more common in merging clusters, like deviations from spherical symmetry in the thermodynamic quantities of the ICM. This last result has been achieved with a new technique for deriving temperature maps from images. We have also detected a cold front and, with the combined use of XMM-Newton and Chandra, we have characterized its properties, such as the speed and the metal abundance profile across the edge. This cold front is probably due to the sloshing of the core, induced by the perturbation of the gravitational potential associated with a past merger. The hydrodynamic processes related to this perturbation have presumably produced a tail of lower entropy, higher pressure and metal rich ICM, which extends behind the cold front for kpc. The unique characteristics of A3558 are probably due to the very peculiar environment in which it is located: the core of the Shapley supercluster.