Physical properties of the X-ray gas as a dynamical diagnosis for galaxy clusters

Abstract

We analysed XMM-{\it Newton} EPIC data for 53 galaxy clusters. Through 2D spectral maps, we provide the most detailed and extended view of the spatial distribution of temperature (kT), pressure (P), entropy (S) and metallicity (Z) of galaxy clusters to date with the aim of correlating the dynamical state of the system to six cool-core diagnoses from the literature. With the objective of building 2D maps and resolving structures in kT, P, S and Z, we divide the data in small regions from which spectra can be extracted. Our analysis shows that when clusters are spherically symmetric the cool-cores (CC) are preserved, the systems are relaxed with little signs of perturbation, and most of the CC criteria agree. The disturbed clusters are elongated, show clear signs of interaction in the 2D maps, and most do not have a cool-core. However, 16 well studied clusters classified as CC by at least four criteria show spectral maps that appear disturbed. All of these clusters but one show clear signs of recent mergers, with a complex structure and geometry but with a cool-core that remains preserved. Thus, although very useful for CC characterization, most diagnoses are too simplistic to reproduce the overall structure and dynamics of galaxy clusters, and therefore the selection of relaxed systems according to these criteria may affect mass estimates. The complex structure of galaxy clusters can be reliably assessed through the 2D maps presented here.