paper

The hot circumgalactic media of massive cluster satellites in the TNG-Cluster simulation: existence and detectability

arXiv:2311.06337 · doi:10.1051/0004-6361/202348583

Abstract

The most massive galaxy clusters in the Universe host hundreds of massive satellite galaxies~$\mstar\sim10^{10-12.5} msun$, but it is unclear if these satellites are able to retain their own gaseous halos. We analyze the evolution of satellites of stellar mass around 352 galaxy clusters of mass $\mvir\sim10^{14.3-15.4} msun$ at from the new TNG-Cluster suite of cosmological magneto-hydrodynamical galaxy cluster simulations. The number of massive satellites per host increases with host mass, and the mass--richness relation broadly agrees with observations. A halo of mass $\mvirhost\sim10^{14.5} (10^{15}) msun$ hosts satellites today. Only a minority of satellites retain some gas, hot or cold, and this fraction increases with stellar mass. Lower-mass satellites are more likely to retain part of their cold interstellar medium, consistent with ram pressure preferentially removing hot extended gas first. At higher stellar masses , the fraction of gas-rich satellites increases to unity, and nearly all satellites retain a portion of their hot, spatially extended circumgalactic medium (CGM), despite the ejective activity of their supermassive black holes. According to TNG-Cluster, the CGM of these gaseous satellites can be seen in soft X-ray emission (0.5-2.0 keV) that is ~times brighter than the local background. This X-ray surface brightness excess around satellites extends to kpc, and is strongest for galaxies with higher stellar masses and larger host-centric distances. Approximately ~percent of the soft X-ray emission in cluster outskirts $\approx0.75-1.5\rvir$ originates from satellites. The CGM of member galaxies reflects the dynamics of cluster-satellite interactions and contributes to the observationally inferred properties of the intracluster medium.

Submitted to A&A, comments welcome. See companion papers by Nelson et al., Lehle et al., Truong et al., Lee et al., and Ayromlou et al., and see the TNG-Cluster website at www.tng-project.org/cluster/. Reuploaded after acceptance for publication

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