Letter to the Editor

XMM-Newton observations of the Coma cluster relic 1253+275

¹ Istituto di Radioastronomia – INAF, via P. Gobetti 101, 40129 Bologna, Italy e-mail: lferetti@ira.inaf.it
² AIM – UMR 7158 CEA – CNRS, Université Paris VII, DSM/DAPNIA/Service d'Astrophysique, CEA/Saclay, L'Orme des Merisiers, Bât. 709, 91191 Gif-sur-Yvette, France e-mail: dneumann@cea.fr

Received: 10 January 2006
Accepted: 15 February 2006

Abstract

Aims.Using XMM Newton data, we investigate the nature of the X-ray emission in the radio relic 1253+275 in the Coma cluster. We determine the conditions of the cluster gas to check current models of relic formation, and we set constraints on the intracluster magnetic field.

Methods.Both imaging and spectral analysis are performed, and the X-ray emission is compared with the radio emission.

Results.We found that the emission is of thermal origin and is connected to the sub-group around NGC 4839. The best-fit gas temperature in the region of the relic and in its vicinity is in the range 2.8-4.0 keV, comparable to the temperature of the NGC 4839 sub-group. We do not detect any high temperature gas, resulting from a possible shock in the region of the Coma relic. We therefore suggest that the main source of energy for particles radiating in the radio relic is likely to be turbulence. From the X-ray data, we can also set a flux upper limit of  erg cm^-2 s^-1, in the 0.3-10 keV energy range, to the non-thermal emission in the relic region. This leads to a magnetic field G.