Cosmic ray heating in cool core clusters - II. Self-regulation cycle and non-thermal emission

Understand

Self-regulated feedback by active galactic nuclei (AGNs) appears to be critical in balancing radiative cooling of the low-entropy gas at the centres of galaxy clusters and in regulating star formation in central galaxies.

• In a companion paper, we found steady-state solutions of the hydrodynamic equations that are coupled to the CR energy equation for a large cluster sample.
• In those solutions, radiative cooling in the central region is balanced by streaming CRs through the generation and dissipation of resonantly generated Alfv{\'e}n waves and by thermal conduction at large radii.
• Here we demonstrate that the predicted non-thermal emission resulting from hadronic CR interactions in the intra-cluster medium exceeds observational radio (and gamma-ray) data in a subsample of clusters that host radio mini halos (RMHs).