The Properties of the Galactic Hot Gaseous Halo from X-ray Emission

Abstract

The extended hot X-ray emitting gaseous halo of the Milky Way has an optical depth $\sim 1$ for the dominant emission lines of \ion{O}{7} and \ion{O}{8}, which are used to infer the halo properties. To improve on halo gas properties, we treat optical depth effects with a Monte-Carlo radiative transfer model, which leads to slightly steeper density profiles ($\beta \approx 0.5$) than if optical depths effects were ignored. For the preferred model where the halo is rotating on cylinders at $180$ km s${}^{-1}$, independent fits to both lines lead to identical results, where the core radius is $2.5$ kpc and the turbulent component of the Doppler b parameter is $100-120$ km s${}^{-1}$; the turbulent pressure is $20\%$ of the thermal pressure. The fit is improved when emission from a disk is included, with a radial scale length of $3$ kpc (assumed) and a fitted vertical scale height of approximately $1.3$ kpc. The disk component is a minor mass constituent and has low optical depth, except at low latitudes. The gaseous mass is $3-4\times 10^{10}{M}_{\odot }$ within $250\mathrm{kpc}$, similar to our previous determinations and significantly less than the missing baryons of $1.7\times 10^{11}{M}_{\odot }$.

References in corpus (15)

• Giant Gamma-ray Bubbles from Fermi-LAT: AGN Activity or Bipolar Galactic Wind?
• The Search for the Missing Baryons at Low Redshift
• Constraining the Milky Way's Hot Gas Halo with OVII and OVII Emission Lines
• X-ray coronae in simulations of disc galaxy formation
• X-Ray Absorption from the Milky Way Halo and the Local Group
• Where are the ``Missing'' Galactic Baryons?
• The Athena X-ray Integral Field Unit (X-IFU)
• The Trouble with the Local Bubble
• The Interaction of the Fermi Bubbles with the Milky Way's Hot Gas Halo
• XMM-Newton Survey of Local O VII Absorption Lines in the Spectra of Active Galactic Nuclei
• X-ray and UV spectroscopy of Galactic diffuse hot gas along the LMC X--3 sight line
• Chandra and Far Ultraviolet Spectroscopic Explorer Observations of z~0 Warm-Hot Gas Toward PKS 2155-304
• High Resolution X-ray Spectroscopy of the Local Hot Gas along the 3C 273 Sightline
• A deep Chandra observation of the hot gaseous halo around a rare, extremely massive and relativistic jet launching spiral galaxy
• Discovery of Galactic OIV and OV X-ray absorption due to transition temperature gas in the PKS 2155-304 spectrum

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• The Solar-Cycle Temporal Variation of the Solar Wind Charge Exchange X-ray Lines
• The soft X-ray background with Suzaku: I. Milky Way halo