Correlation of AGN Jet Power with the Entropy Profile in Cooling Flow Clusters

TL;DR

This study reveals that AGN jet power in cooling flow galaxy clusters correlates with the entropy profile and gas mass in the inner regions, supporting the cold feedback mechanism and suggesting entropy as a key feedback regulator.

Contribution

It introduces new correlations between jet power, entropy profile, and gas mass, emphasizing the importance of entropy in AGN feedback models.

Findings

Jet power correlates with the size of the flat entropy region.

Jet power correlates with the gas mass in the flat entropy region.

Molecular gas mass also correlates with entropy profile parameters.

Abstract

We find that the power of jets that inflate bubble pairs in cooling flow clusters of galaxies correlates with the size of the inner region where the entropy profile is flat, as well as with the gas mass in that region and the entropy floor (the entropy value at the center of the cluster). These correlations strengthen the cold feedback mechanism that is thought to operate in cooling flow clusters and during galaxy formation. In the cold feedback mechanism the central super-massive black hole (SMBH) is fed with cold clumps that originate in an extended region of the cooling flow volume, in particular from the inner region that has a flat entropy profile. Such a process ensures a tight feedback between radiative cooling and heating by the SMBH (the AGN). The derived expressions should be used instead of the Bondi accretion rate when studying AGN feedback. We find that the mass of molecular gas also correlates with the entropy profile parameters, despite that the jet power does not correlate with the molecular gas mass. This further suggests that the entropy profile is a fundamental parameter determining cooling and feedback in cooling flow clusters.