Jet interaction with galaxy cluster mergers

AGN bubbles in cool-core galaxy clusters are believed to significantly facilitate the transport of cosmic ray electrons (CRe) throughout the cluster. Recent radio observations are revealing complex morphologies of cluster diffuse emission, potentially linked to interactions between AGN bursts and the cluster environment. We perform three-dimensional magneto-hydrodynamical simulations of binary cluster mergers and inject a bi-directional jet at the center of the main cluster. Kinetic, thermal, magnetic and CRe energy are included in the jet and we use the two-fluid formalism to model the CRe component. We explore a wide range of cluster merger and jet parameters. We discuss the formation of various wide-angle-tail (WAT) and X-shaped sources in the course of the early evolution of the jet and merger. During the last phase of the evolution, we find that the CR material efficiently permeates the central region of the cluster reaching radii of $\sim1$--2 Mpc within $\sim5$--6 Gyr, depending on the merger mass ratio. We find that solenoidal turbulence dominates during the binary merger and explore the possibility for the CRe jet material to be re-accelerated by super-Alfv\`enic turbulence and contribute to cluster scale radio emission. We find that the emission can be volume-filing, $\gtrsim 70$\%. Finally, we study the merger shock interaction with the CRe material and show that it is unlikely that this material significantly contributes to the radio relic emission associated with the shocks. We suggest that multiple jet outbursts and/or off-center radio galaxies would increase the likelihood of detecting these merger shocks in the radio due to shock re-acceleration.
Comment: 29 pages, 18 figures, submitted to ApJ, comments welcome