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Abstract
Abstract The circumgalactic medium (CGM) around massive galaxies plays a crucial role in regulating star formation and feedback. Using the Cosmology and Astrophysics with MachinE Learning Simulations (CAMELS) suite, we develop emulators for the X-ray surface brightness profile and the X-ray luminosity–stellar mass scaling relation, to investigate how stellar and active galactic nucleus (AGN) feedback shape the X-ray properties of the hot CGM. Our analysis shows that at CGM scales (1012 ≲ M halo/M ⊙ ≲ 1013, 10 ≲ r kpc−1 ≲ 400), stellar feedback more significantly impacts the X-ray properties than AGN feedback within the parameters studied. Comparing the emulators to recent eROSITA All Sky Survey (eRASS) observations, it is found that stronger feedback than is currently implemented in the IllustrisTNG, SIMBA, and Astrid simulations is required to match the observed CGM properties. However, adopting these enhanced feedback parameters causes deviations in the stellar mass–halo mass relations from observational constraints below the group-mass scale. This tension suggests possible unaccounted-for systematics in X-ray CGM observations or inadequacies in the feedback models of cosmological simulations.
Highlights
The circumgalactic medium (CGM) around massive galaxies plays a fundamental role in galaxy evolution (Tumlinson et al 2017; Faucher-Giguere & Oh 2023, for reviews)
Using the Cosmology and Astrophysics with MachinE Learning Simulations (CAMELS) simulation suite, we develop emulators for the X-ray surface brightness profile and the X-ray luminosity–stellar mass scaling relation to investigate how stellar and active galactic nuclei (AGN) feedback shape the X-ray properties of the hot CGM
We demonstrate how the X-ray surface brightness (XSB) profiles from CAMELS-IllustrisTNG, CAMELS-SIMBA, and CAMELSAstrid depend on the feedback parameters and how they compare with the eROSITA All Sky Survey (eRASS) observation
Summary
The circumgalactic medium (CGM) around massive galaxies plays a fundamental role in galaxy evolution (Tumlinson et al 2017; Faucher-Giguere & Oh 2023, for reviews). Recent stacked X-ray observations from the eROSITA Final Exposure Depth Survey (eFEDS) fields (Chadayammuri et al 2022; Comparat et al 2022) inferred that the CGM Xray luminosity seems to be lower than that of cosmological simulations at higher stellar mass halos. These results are still uncertain given the statistical uncertainties due to cosmic variances in the stacking procedures. Compared to the 140 square degree eFEDS field, the half-sky coverage of eRASS contains a much larger galaxy sample for stacking, which increases the signal-to-noise ratio by a factor of a few, reducing the statistical uncertainty on the stacked signal, potentially allowing for better constraints on CGM properties and their physics
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