Kavli Affiliate: Mark Vogelsberger
| First 5 Authors: , , , ,
| Summary:
Current galaxy formation models predict the existence of X-ray-emitting
gaseous halos around Milky Way (MW)-type galaxies. To investigate properties of
this coronal gas in MW-like galaxies, we analyze a suite of high-resolution
simulations based on the SMUGGLE framework and compare the results with X-ray
observations of both the MW and external galaxies. We find that for subgrid
models incorporating any form of stellar feedback, e.g., early feedback
(including stellar winds and radiation) and/or supernova (SN) explosions, the
total 0.5-2 keV luminosity is consistent within uncertainties with X-ray
observations of the MW and with scaling relations derived for external disk
galaxies. However, all models exhibit an X-ray surface brightness profile that
declines too steeply beyond $sim5$ kpc, underpredicting the extended emission
seen in recent eROSITA stacking results. Across all subgrid prescriptions, the
simulated surface brightness and emission measure fall below MW observations by
at least 1-2 orders of magnitude, with the most severe discrepancy occurring in
the no-feedback model. Our results suggest that (i) stellar feedback primarily
shapes the innermost hot atmosphere (central $sim5$ kpc), with comparable
contributions from early feedback and SNe to the resulting X-ray luminosity;
(ii) additional mechanisms such as gravitational heating, active galactic
nuclei feedback, and/or Compton effects of GeV cosmic ray are necessary to
generate the extended, volume-filling hot gaseous halo of MW-mass galaxies;
(iii) the origins of hot corona in MW-like galaxies are partially distinct from
those of the warm ($sim10^5$ K) gas, by combining our previous finding that
the SMUGGLE model successfully reproduces the kinematics and spatial
distribution of MW O VI absorbers.
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