📝 SummarXiv

Abstract

Shock fronts driven by active galactic nuclei in galaxy cluster cores represent a promising mechanism to heat the intracluster gas by converting kinetic energy into thermal energy through gas compression, thereby offsetting radiative cooling. Despite their potential importance, such shocks are challenging to detect, requiring deep X-ray exposures, and have only been identified in ten clusters. We present the first systematic detection and characterization of AGN-driven shocks in simulated clusters from the TNG-Cluster magnetohydrodynamic cosmological zoom-in simulations of galaxies. TNG-Cluster exhibits a rich variety of X-ray structures, including realistic populations of X-ray cavities, as well as shocks, produced by its AGN feedback model, without collimated, relativistic jets, nor cosmic rays. We produce mock Chandra observations with deep exposure times, for a sample of 100 clusters, mass-matched (M$_{500c}=1.2$ - $8.5 \times 10^{14}$ M$_\odot$) to the ten observed clusters with shocks. Using observational techniques, we identify shocks through surface brightness edges fitted with broken power laws and associated density and temperature jumps. We detect 50 shocks in 30 of the 100 clusters, with ~35% hosting multiple shocks. These shocks lie within a hundred kiloparsec of the central SMBH, are weak (Mach number < 2, median ~ 1.1), and are associated with cavities in about half of the cases. Both in observations and in TNG-Cluster, shocks tend to be located at larger radii than cavities, with median offsets of 46 and 27 kpc, respectively. The observationally inferred shock powers are comparable to the cluster cooling luminosities (10$^{44-46}$ erg s$^{-1}$), suggesting that shocks in the simulation are crucial heating mechanisms. Our results indicate that shocks play a role as important as cavities in balancing cooling in cluster cores, acting isotropically and up to larger distances.