Simulating AGN feedback in galaxy clusters with pre-existing turbulence

TL;DR

This study uses 3D hydrodynamic simulations to assess the roles of AGN feedback and pre-existing turbulence in heating galaxy cluster cores, finding turbulence alone insufficient to counteract cooling.

Contribution

It provides a detailed simulation analysis showing that turbulence, even when pre-existing, does not dominate heating compared to AGN feedback in galaxy clusters.

Findings

Turbulent heating rate is smaller than radiative cooling rate.

AGN feedback remains a significant heating mechanism.

Turbulence alone cannot offset cooling in cluster cores.

Abstract

Feedback from active galactic nuclei (AGN) is believed to play a significant role in suppressing cooling flows in cool-core (CC) clusters. Turbulence in the intracluster medium (ICM), which may be induced by AGN activity or pre-existing motions, has been proposed as a potential heating mechanism based on analysis of Chandra X-ray surface brightness fluctuations. However, subsequent simulation results have found the subdominant role of turbulence in heating the ICM. To investigate this discrepancy, we perform three-dimensional hydrodynamic simulations of a Perseus-like cluster including both AGN feedback and pre-existing turbulence, which is stirred to the observationally constrained level in the Perseus cluster. Our results indicate that, although the velocity field is dominated by the pre-existing turbulence, AGN heating through bubbles and shocks remains significant. More importantly, analysis of the velocity structure function and the energy power spectrum shows that the turbulent heating rate is smaller than the radiative cooling rate, especially in the cluster core. Our results offer insights relevant for recent XRISM observations and indicate that turbulent heating alone cannot offset radiative cooling in CC clusters.