Energy Deposition Profiles and Entropy in Galaxy Clusters

TL;DR

This study analyzes entropy profiles in galaxy clusters, estimating non-gravitational energy deposition and supporting AGN feedback as a key process in entropy enhancement.

Contribution

First estimation of total and radial non-gravitational energy deposition in galaxy clusters using XMM-Newton data, linking entropy enhancement to AGN feedback.

Findings

Energy deposition proportional to cluster temperature

Radial energy deposition profile consistent across clusters

Supports AGN feedback as a mechanism for entropy increase

Abstract

We report the results of our study of fractional entropy enhancement in the intra-cluster medium (ICM) of the clusters from the representative XMM-Newton cluster structure survey (REXCESS). We compare the observed entropy profile of these clusters with that expected for the ICM without any feedback, as well as with the introduction of preheating and entropy change due to gas cooling. We make the first estimate of the total, as well as radial, non-gravitational energy deposition up to r500 for a large, nearly flux-limited, sample of clusters. We find that the total energy deposition corresponding to the entropy enhancement is proportional to the cluster temperature (and hence mass), and that the energy deposition per particle as a function of gas mass shows a similar profile in all clusters, with its being more pronounced in the central region than in the outer region. Our results support models of entropy enhancement through AGN feedback.