SIMBAD references

2013ApJ...770..118M - Astrophys. J., 770, 118 (2013/June-3)

The structure of the Milky Way's hot gas halo.


Abstract (from CDS):

The Milky Way's million degree gaseous halo contains a considerable amount of mass that, depending on its structural properties, can be a significant mass component. In order to analyze the structure of the Galactic halo, we use XMM-Newton Reflection Grating Spectrometer archival data and measure O VII Kα absorption-line strengths toward 26 active galactic nuclei, LMC X-3, and two Galactic sources (4U 1820-30 and X1735-444). We assume a β-model as the underlying gas density profile and find best-fit parameters of n{cir}= 0.46–0.35+0.74/cm3, rc= 0.35–0.27+0.29 kpc, and β = 0.71–0.14+0.13. These parameters result in halo masses ranging between M(18 kpc) = 7.5–4.6+22.0 x 108 M and M(200 kpc) = 3.8–0.5+6.0 x 1010 M assuming a gas metallicity of Z = 0.3 Z, which are consistent with current theoretical and observational work. The maximum baryon fraction from our halo model of fb= 0.07–0.01+0.03 is significantly smaller than the universal value of fb= 0.171, implying the mass contained in the Galactic halo accounts for 10%-50% of the missing baryons in the Milky Way. We also discuss our model in the context of several Milky Way observables, including ram pressure stripping in dwarf spheroidal galaxies, the observed X-ray emission measure in the 0.5-2 keV band, the Milky Way's star formation rate, spatial and thermal properties of cooler gas (∼105 K), and the observed Fermi bubbles toward the Galactic center. Although the metallicity of the halo gas is a large uncertainty in our analysis, we place a lower limit on the halo gas between the Sun and the Large Magellanic Cloud (LMC). We find that Z ≳ 0.2 Z based on the pulsar dispersion measure toward the LMC.

Abstract Copyright:

Journal keyword(s): Galaxy: halo - X-rays: diffuse background

Simbad objects: 40

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