Metal abundances in the cool cores of galaxy clusters^*

¹ INAF – Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate (LC), Italy e-mail: sabrina.degrandi@brera.inaf.it
² INAF – IASF Milano, via Bassini 15, 20133 Milano, Italy e-mail: silvano@iasf-milano.inaf.it

Received: 22 June 2009
Accepted: 27 August 2009

Abstract

We use XMM-Newton data to carry out a detailed study of the Si, Fe and Ni abundances in the cool cores of a representative sample of 26 local clusters. We performed a careful evaluation of the systematic uncertainties related to the instruments, the plasma codes and the spectral modeling, finding that the major source of uncertainty is the plasma codes. Our Si, Fe, Ni, Si/Fe and Ni/Fe distributions feature only moderate spreads (from 20% to 30%) around their mean values strongly suggesting similar enrichment processes at work in all our cluster cores. Our sample-averaged Si/Fe ratio is comparable to those measured in samples of groups and high luminosity ellipticals, implying that the enrichment process in ellipticals, dominant galaxies in groups and BCGs in clusters is quite similar. Although our Si/Fe and Ni/Fe abundance ratios are fairly well constrained, the large uncertainties in the supernova yields prevent us from making a firm assessment of the relative contribution of type Ia and core-collapsed supernovae to the enrichment process. All that can be said with some certainty is that both contribute to the enrichment of cluster cores.