AGN feedback and entropy injection in galaxy cluster cores

TL;DR

This study estimates the non-gravitational energy profiles in galaxy cluster cores from observational data, compares them with simulations, and explores the role of AGN feedback in energy injection, revealing correlations with cluster temperature and radio luminosity.

Contribution

First observational estimates of non-gravitational energy profiles in galaxy clusters, linking AGN activity to energy feedback in cluster cores.

Findings

Energy feedback scales with cluster temperature as T^{2.52} (SPH) and T^{2.17} (AMR).

Mean non-gravitational energy per particle is about 2.8 keV (SPH) and 1.7 keV (AMR).

Feedback energy correlates with radio luminosity for T > 3 keV.

Abstract

The non-gravitational energy feedback is of crucial importance in modeling/simulating clusters to be used as cosmological probes. AGNs are, arguably, of primary importance in injecting energy in the cluster cores. We make the first estimate of non-gravitational energy {\it profiles} in galaxy cluster cores (and beyond) from observational data. Comparing the observed entropy profiles within $r_{500}$, from the Representative {\it XMM-Newton} Cluster Structure Survey (REXCESS), to simulated entropy profiles from both AMR and SPH non-radiative simulations, we estimate the amount of non-gravitational energy, $E_{\rm ICM}$, contained in the ICM. Adding the radiative losses we estimate the total energy feedback, $E_{\rm Feedback}$, into the clusters. The profiles for the energy deposition, $\Delta E_{\rm ICM}(x)$, in the inner regions differ for Cool-Core (CC) and Non Cool-Core (NCC) clusters, decreasing after accounting for the radiative cooling. The total feedback energy scales with the mean spectroscopic temperature as $E_{\rm Feedback} \propto T_{\rm sp}^{2.52 \pm0.08}$ and $E_{\rm Feedback} \propto T_{\rm sp}^{2.17 \pm 0.11}$, when compared with the baseline SPH and AMR profiles respectively. The scatter in the two cases is 15% and 23%, respectively. The mean non-gravitational energy per particle within $r_{500}$, is $\epsilon_{\rm ICM} = {2.8} \pm {0.8}$ keV for the SPH theoretical relation and $\epsilon_{\rm ICM} = {1.7} \pm {0.9}$ keV for the AMR theoretical relation. We use the {\it NRAO/VLA Sky Survey} (NVSS) source catalog to determine the radio luminosity, $L_R$, at 1.4 GHz of the central source(s) of our sample. For $T_{\rm sp} > 3$ keV, the $E_{\rm Feedback}$ correlates with $L_R$. We show that AGNs could provide a significant component of the feedback. (Abridged)