The warm-hot circumgalactic medium of the Milky Way as seen by eROSITA

Abstract

The first all-sky maps of the diffuse emission of high ionization lines observed in X-rays by SRG/eROSITA, provide an excellent probe for the study of the warm-hot phase (T~10^6 K) of the circumgalactic medium (CGM) of the Milky Way (MW). In this work we analyse the O VIII line detected in the first eROSITA All-Sky Survey data (eRASS1). We fit a sky map made in a narrow energy bin around this line, with physical emission models embedded in a 3D geometry to constrain the density distribution of the warm-hot gas around our Galaxy, with a focus on mid and high (absolute) Galactic latitudes. By masking out the eROSITA bubbles and other bright extended foreground sources, we find that an oblate geometry of the warm-hot gas (T~0.15-0.17 keV), flattened around the Galactic disk with scale height z_h~1-3 kpc, best describes the eRASS1 O VIII map, with most of the observed emission resulting to be produced within a few kpc from the Sun. The additional presence of a large scale warm-hot spherical halo, while providing a minor contribute to the X-ray emission, accounts for the high O VII absorption column densities detected with XMM-Newton, as well as most of the baryon budget of the CGM of the MW. The eROSITA data carry the largest amount of information and detail of O VIII CGM intensities to date, allowing for a significant reduction of the statistical uncertainties of the inferred physical parameters.

Accepted for publication in Astronomy & Astrophysics

References in corpus (33)

• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• HI4PI: A full-sky HI survey based on EBHIS and GASS
• The EAGLE simulations of galaxy formation: calibration of subgrid physics and model variations
• The Circumgalactic Medium
• The mass distribution and gravitational potential of the Milky Way
• The eROSITA X-ray telescope on SRG
• The SRG X-ray orbital observatory, its telescopes and first scientific results
• Gaia-2MASS 3D maps of Galactic interstellar dust within 3 kpc
• The eROSITA Final Equatorial Depth Survey (eFEDS): The X-ray catalog
• Constraining the Milky Way's Hot Gas Halo with OVII and OVII Emission Lines
• Unifying X-ray Scaling Relations from Galaxies to Clusters
• X-Ray Absorption from the Milky Way Halo and the Local Group
• The gas-to-extinction ratio and the gas distribution in the Galaxy
• OVII and OVIII line emission in the diffuse soft X-ray background: heliospheric and galactic contributions
• The Structure of the Local Hot Bubble
• The Circum-Galactic Medium of MASsive Spirals II: Probing the Nature of Hot Gaseous Halo around the Most Massive Isolated Spiral Galaxies
• X-ray and UV spectroscopy of Galactic diffuse hot gas along the LMC X--3 sight line
• A disk-dominated and clumpy circumgalactic medium of the Milky Way seen in X-ray emission
• The eROSITA Final Equatorial Depth Survey (eFEDS): X-ray emission around star-forming and quiescent galaxies at $0.05<z<0.3$
• Abundance and temperature of the outer hot circum-Galactic medium: The SRG/eROSITA view of the soft X-ray background in the eFEDS field
• First eROSITA study of nearby M dwarfs and the rotation-activity relation in combination with TESS
• Intermediate- and high-velocity clouds in the Milky Way I: covering factors and vertical heights
• The hot circumgalactic medium of the Milky Way: evidence for super-virial, virial, and sub-virial temperature, non-solar chemical composition, and non-thermal line broadening
• The Properties of the Galactic Hot Gaseous Halo from X-ray Emission
• HaloSat -- A CubeSat to Study the Hot Galactic Halo
• Super-virial temperature or Neon overabundance?: Suzaku observations of the Milky Way circumgalactic Medium
• Widespread Detection of Two Components in the Hot Circumgalactic Medium of the Milky Way
• Figuring Out Gas & Galaxies In Enzo (FOGGIE) VI: The Circumgalactic Medium of $L^{\ast }$ Galaxies is Supported in an Emergent, Non-Hydrostatic Equilibrium
• SRG/eROSITA X-ray shadowing study of giant molecular clouds
• Bird's eye view of molecular clouds in the Milky Way: I. Column density and star formation from sub-pc to kpc scales
• Figuring Out Gas & Galaxies In Enzo (FOGGIE) V: The Virial Temperature Does Not Describe Gas in a Virialized Galaxy Halo
• The hot circumgalactic medium of the Milky-Way: new insights from XMM-Newton observations
• Cold and Hot gas distribution around the Milky-Way-M31 system in the HESTIA simulations

Cited by in corpus (19)

• The SRG/eROSITA all-sky survey: First X-ray catalogues and data release of the western Galactic hemisphere
• The hot circumgalactic medium in the eROSITA All-Sky Survey I. X-ray surface brightness profiles
• A magnetised Galactic halo from inner Galaxy outflows
• Quantifying Observational Projection Effects with a Simulation-based hot CGM model
• eROSITA X-ray Analysis of the PeVatron Candidate Westerlund 1
• eROSITA narrowband maps at the energies of soft X-ray emission lines
• Searching for cold gas traced by MgII quasar absorbers in massive X-ray-selected galaxy clusters
• Understanding the Baryon Cycle: Fueling Star Formation via Inflows in Milky Way-like Galaxies
• Discovery of the Goat Horn complex: a $\sim 1000$ deg${}^2$ diffuse X-ray source connected to radio loop XII
• Cross-correlation between soft X-rays and galaxies A new benchmark for galaxy evolution models
• On the origin of the $10^7$ K hot emitting gas in the Circumgalactic medium of the Milky Way
• A new understanding of the Gemini-Monoceros X-ray enhancement from discoveries with eROSITA
• Introducing the Descriptive Parametric Model: Gaseous Profiles for Galaxies, Groups, and Clusters
• Retrieving the hot circumgalactic medium physics from the X-ray radial profile from eROSITA with an IlustrisTNG-based forward model
• Implications of the Milky Way Declining Rotation Curve
• Can galactic magnetic fields diffuse into the voids?
• On the baryon budget in the X-ray-emitting circumgalactic medium of Milky Way-mass galaxies
• Soft X-ray line emission from hot gas in intervening galaxy halos and diffuse gas in the cosmic web
• Prospects for studying million-degree gas in the Milky Way halo using the forbidden optical [FeX] and [FeXIV] intersystem lines