One possibility is that a substantial fraction of the Galaxy’s baryons are embeddedwithin an extended, million-degree hot halo, an idea supported indirectly by observations of warm gasclouds in the halo and gas-free dwarf spheroidal satellites. Taotao Fang, James Bullock, and Michael Boylan-Kolchin (Received Revised Accepted) Draft version November 1, 2018ĪBSTRACTThe Milky Way appears to be missing baryons, as the observed mass in stars and gas is well belowthe cosmic mean. ON THE HOT GAS CONTENT OF THE MILKY WAY HALO Preprint typeset using L A TEX style emulateapj v. We briefly discuss some potential avenues for discriminating between a massive, extended hot halo and a local hot disk. However, if the hot corona of the galaxy is in an extended, low-density distribution with a large central core, as expected for an adiabatic gas in hydrostatic equilibrium, then it may contain up to 10^11 M_sun of material, possibly accounting for all of the missing Galactic baryons. In agreement with past studies, we find that a baryonically closed halo is clearly ruled out if one assumes that the hot corona is distributed with a cuspy NFW profile. Here we re-examine the observational data, particularly in the X-ray and radio bands, in order to determine whether it is possible for a substantial fraction of the Galaxy's baryons to exist in ~ 10^6 K gas. Moreover, recent investigations into the X-ray constraints have suggested that any Galactic corona must be insignificant. ![]() X-ray observations have established that hot gas does exist in our Galaxy beyond the local hot bubble however, it may be distributed in a hot disk configuration. ![]() One possibility is that a substantial fraction of the Galaxy's baryons are embedded within an extended, million-degree hot halo, an idea supported indirectly by observations of warm gas clouds in the halo and gas-free dwarf spheroidal satellites. The Milky Way appears to be missing baryons, as the observed mass in stars and gas is well below the cosmic mean.
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