Kavli Affiliate: Feng Yuan
| First 5 Authors: Zhijie Zhang, Zhijie Zhang, , ,
| 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 it 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 it 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, AGN 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 it SMUGGLE model successfully reproduces the kinematics and spatial
distribution of MW ionO6 absorbers citep2024ApJ…962…15Z.
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