XMM-Newton observation of the interacting cluster Abell 3528^*

¹ IASF – CNR Sezione di Milano “G. Occhialini”, Via Bassini 15, 20133 Milano, Italy
² Università di Milano Bicocca, Dip. di fisica, P.za della Scienza 3, 20126 Milano, Italy
³ European Southern Observatory, Karl-Schwarzschild-Straße 2, 85748 Garching bei München, Germany
⁴ INAF – Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
⁵ Istituto di Radioastronomia del CNR, via Gobetti 101, 40129, Bologna, Italy

Corresponding author: F. Gastaldello, gasta@mi.iasf.cnr.it

Received: 9 May 2003
Accepted: 29 July 2003

Abstract

We analyze the XMM-Newton dataset of the interacting cluster of galaxies Abell 3528 located westward in the core of the Shapley Supercluster, the largest concentration of mass in the nearby Universe. A3528 is formed by two interacting clumps (A3528-N at North and A3528-S at South) separated by 0.9  Mpc at redshift 0.053. XMM-Newton data describe these clumps as a relaxed structure with an overall temperature of and  keV in A3528-N and A3528-S, respectively, and a core cooler by a factor 1.4–1.5 and super-solar metal abundance in the inner 30 arcsec. These clumps are connected by a X-ray soft, bridge-like emission and present an asymmetric surface brightness with significant excess in the North–West region of A3528-N and in the North–East area of A3528-S. However, we do not observe any evidence of shock heated gas, both in the surface brightness and in the temperature map. Considering also that the optical light distribution is more concentrated around A3528-N and makes A3528-S barely detectable, we do not find support for the originally suggested head-on pre-merging scenario and conclude that A3528 is in an off-axis post-merging phase, where the closest core encounter happened about 1–2 Gyrs ago.