Quasisteady Configurations of Conductive Intracluster Media

TL;DR

This paper develops steady-state models of cool-core galaxy clusters considering cooling, conduction, and AGN feedback, revealing how these processes shape observed temperature and entropy profiles.

Contribution

It introduces a comprehensive steady-state framework incorporating cooling, conduction, and feedback to interpret cool-core cluster configurations.

Findings

Many cool-core clusters have entropy levels just below conductively balanced solutions.

AGN feedback is triggered when conduction cannot offset radiative cooling.

Conduction remains a key heating process within the central 100 kpc of clusters.

Abstract

The radial distributions of temperature, density, and gas entropy among cool-core clusters tend to be quite similar, suggesting that they have entered a quasi-steady state. If that state is regulated by a combination of thermal conduction and feedback from a central AGN, then the characteristics of those radial profiles ought to contain information about the spatial distribution of AGN heat input and the relative importance of thermal conduction. This paper addresses those topics by deriving steady-state solutions for clusters in which radiative cooling, electron thermal conduction, and thermal feedback fueled by accretion are all present, with the aim of interpreting the configurations of cool-core clusters in terms of steady-state models. It finds that the core configurations of many cool-core clusters have entropy levels just below those of conductively balanced solutions in which magnetic fields have suppressed electron thermal conduction to ~1/3 of the full Spitzer value, suggesting that AGN feedback is triggered when conduction can no longer compensate for radiative cooling. And even when feedback is necessary to heat the central ~30 kpc, conduction may still be the most important heating mechanism within a cluster's central ~100 kpc.