Temperature structure of the intergalactic medium within seven nearby and bright clusters of galaxies observed with XMM-Newton

TL;DR

This study maps the temperature structure of the intra-cluster medium in seven nearby galaxy clusters using advanced spectral mapping with XMM-Newton, revealing complex thermal features related to cluster dynamics and merger activity.

Contribution

Introduces a B-spline wavelet-based spectral mapping algorithm to analyze the temperature structure of galaxy clusters from X-ray data, providing detailed insights into cluster dynamics.

Findings

Major mergers show complex thermal structures with strong variations.

Detection of non-radial thermal structures outside cool cores.

Temperature structures can significantly affect mass estimates of clusters.

Abstract

Aims. We map the temperature structure of the intra-cluster medium (ICM) within a nearly complete X-ray flux limited sample of galaxy clusters in the redshift range z=[0.045,0.096]. Our sample contains seven bright clusters of galaxies observed with XMM-Newton: Abell 399, Abell 401, Abell 478, Abell 1795, Abell 2029, Abell 2065, Abell 2256. Methods. We use a multi-scale spectral mapping algorithm especially designed to map spectroscopic observables from X-ray extended emission of the ICM. Derived from a former algorithm using Haar wavelets, our algorithm is now implemented with B-spline wavelets in order to perform a more regular analysis of the signal. Results. For the four clusters in our sample that are major mergers, we find a complex thermal structure with strong thermal variations consistent with their dynamics. For two of them, A2065 and A2256, we perform a 3-d analysis of cold front features evidenced from the gas temperature and brightness maps. Furthermore, we detect a significant non-radial thermal structure outside the cool core region of the other 3 more "regular" clusters, with relative amplitudes of about about 10%. We investigate possible implications of this structure on the mass estimates of the "regular" clusters A1795 and A2029, by extracting surface brightness and temperature profiles from sectors correspondings to the hottest and coldest regions in the maps. While compensating with surface brightness for A2029, leading to consistent mass profiles, the temperature structure leads to significant mass discrepancies in the innermost region of A1795.