X-ray cavities in TNG-Cluster: a direct comparison to observations

Abstract: The TNG-Cluster magnetohydrodynamic cosmological simulations, produce a diverse population of X-ray cavities in the intracluster medium (ICM) of simulated galaxy clusters. These arise from episodic, high velocity, kinetic energy injections from the central active supermassive black hole (AGN, SMBH). Here, we present the first comprehensive comparative analysis of X-ray cavities in TNG-Cluster with observational data. First, we select a volume-limited sample of 35 real clusters ($z \leq 0.071$, M$\text{500c}$ = 10$^{14-14.8}$ M$\odot$) observed with the Chandra X-ray Observatory, identify 3 analogs for each in TNG-Cluster (total of 105) and generate mock Chandra images using same exposure times as their observed counterparts. We identify X-ray cavities and measure their properties in both datasets using identical techniques, ensuring a direct, apples-to-apples comparison. Our analysis reveals that both samples have a similar fraction of X-ray cavities (35-43 per cent). They exhibit comparable sizes and morphologies, although the sizes of simulated X-ray cavities still attached to the SMBH are somewhat larger in TNG-Cluster -- a scarcity at $< 10$ kpc. The area of TNG X-ray cavities increases as they rise in the ICM, consistent with the trend seen in the observational sample. The cavity powers, estimated using observational techniques, show good agreement between the two samples (10$^{42-45}$ erg.s$^{-1}$), suggesting that X-ray cavities in the simulation are an important heating mechanism in cluster cores. Overall, the rather simple AGN feedback model of TNG, with no model choices made to reproduce X-ray morphological features, and without cosmic rays, creates a quantitatively realistic population of X-ray cavities at cluster scales.