Cosmic ray feedback heating of the intracluster medium

Understand

Self-regulating AGN feedback in the cool cores of galaxy clusters plays central role in solving the decades-old cooling flow problem, but one major problem remains unsolved - how is the AGN energy thermalized in the ICM and what are the effective black hole feeding rates in realistic systems? We perform a suite of 3D MHD AMR simulations of AGN feedback in a cool core cluster including cosmic ray (CR) physics.

• CRs are supplied to the ICM via collimated AGN jets and subsequently disperse in the magnetized ICM via streaming, and interact with the ICM via hadronic, Coulomb, and streaming instability heating.
• We find that CR transport is an essential model ingredient needed for AGN feedback to self-regulate, at least within the context of the physical model considered here.
• When CR streaming is neglected, the suppression of CR mixing with the ICM by magnetic fields significantly reduces ICM heating, which leads to cooling catastrophes.