On the relation between mini-halos and AGN feedback in clusters of
  galaxies
  A variety of large-scale diffuse radio structures have been identified in
many clusters with the advent of new state-of-the-art facilities in radio
astronomy. Among these diffuse radio structures, radio mini-halos are found in
the central regions of cool core clusters. Their origin is still unknown and
they are challenging to discover; less than thirty have been published to date.
Based on new VLA observations, we confirmed the mini-halo in the massive strong
cool core cluster PKS 0745$-$191 ($z=0.1028$) and discovered one in the massive
cool core cluster MACS J1447.4+0827 ($z=0.3755$). Furthermore, using a detailed
analysis of all known mini-halos, we explore the relation between mini-halos
and AGN feedback processes from the central galaxy. We find evidence of strong,
previously unknown correlations between mini-halo radio power and X-ray cavity
power, and between mini-halo and the central galaxy radio power related to the
relativistic jets when spectrally decomposing the AGN radio emission into a
component for past outbursts and one for on-going accretion. Overall, our study
indicates that mini-halos are directly connected to the central AGN in
clusters, following previous suppositions. We hypothesize that AGN feedback may
be one of the dominant mechanisms giving rise to mini-halos by injecting energy
into the intra-cluster medium and reaccelerating an old population of
particles, while sloshing motion may drive the overall shape of mini-halos
inside cold fronts. AGN feedback may therefore not only play a vital role in
offsetting cooling in cool core clusters, but may also play a fundamental role
in re-energizing non-thermal particles in clusters.
