The SRG/eROSITA diffuse soft X-ray background. I. The local hot bubble in the western Galactic hemisphere

Abstract

The SRG/eROSITA All-Sky Surveys (eRASSs) combine the advantages of complete sky coverage and the energy resolution provided by the charge couple device and offer the most holistic and detailed view of the diffuse soft X-ray background (SXRB) to date. The first eRASS (eRASS1) was completed at solar minimum, when solar wind charge exchange emission was minimal, providing the clearest view of the SXRB. We aim to extract spatial and spectral information from each constituent of the SXRB in the western Galactic hemisphere, focusing on the local hot bubble (LHB). We extracted and analysed eRASS1 spectra from almost all directions in the western Galactic hemisphere by dividing the sky into equal signal-to-noise bins. We fitted all bins with fixed spectral templates of known background constituents. We find the temperature of the LHB exhibits a north-south dichotomy at high latitudes ($|b|>30^{\circ }$), with the south being hotter, with a mean temperature at $kT=121.8\pm 0.6$eV and the north at $kT=100.8\pm 0.5$eV. At low latitudes, the LHB temperature increases towards the Galactic plane, especially towards the inner Galaxy. The LHB emission measure ($\mathrm{E}{\mathrm{M}}_{\mathrm{LHB}}$) enhances approximately towards the Galactic poles. The $\mathrm{E}{\mathrm{M}}_{\mathrm{LHB}}$ map shows clear anti-correlation with the local dust column density. In particular, we found tunnels of dust cavities filled with hot plasma, potentially forming a wider network of hot interstellar medium. We also constructed a three-dimensional LHB model from $\mathrm{E}{\mathrm{M}}_{\mathrm{LHB}}$, assuming constant density. The average thermal pressure of the LHB is $P_{\mathrm{thermal}}/k=10100_{-1500}^{+1200}\mathrm{c}{\mathrm{m}}^{-3}\mathrm{K}$, a lower value than typical supernova remnants and wind-blown bubbles. This could be an indication of the LHB being open towards high Galactic latitudes.

31 pages, 37 figures, published in A&A

References in corpus (51)

• Array Programming with NumPy
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• HI4PI: A full-sky HI survey based on EBHIS and GASS
• The synthesis of the cosmic X-ray background in the Chandra and XMM-Newton era
• The Chandra Deep Field-South Survey: 7 Ms Source Catalogs
• The SRG X-ray orbital observatory, its telescopes and first scientific results
• The SRG/eROSITA all-sky survey: First X-ray catalogues and data release of the western Galactic hemisphere
• Constraining the Milky Way's Hot Gas Halo with OVII and OVII Emission Lines
• On the use of C-stat in testing models for X-ray spectra
• Detection of large-scale X-ray bubbles in the Milky Way halo
• Contour binning: a new technique for spatially-resolved X-ray spectroscopy applied to Cassiopeia A
• Star formation near the Sun is driven by expansion of the Local Bubble
• Updated Gaia-2MASS 3D maps of Galactic interstellar dust
• A parsec-scale Galactic 3D dust map out to 1.25 kpc from the Sun
• The search for the origin of the Local Bubble redivivus
• X-Ray Absorption from the Milky Way Halo and the Local Group
• The eROSITA Final Equatorial-Depth Survey (eFEDS): Catalog of galaxy clusters and groups
• The Chandra COSMOS legacy survey: Energy Spectrum of the Cosmic X-ray Background and constraints on undetected populations
• The Structure of the Local Hot Bubble
• The Trouble with the Local Bubble
• XMM-Newton Survey of Local O VII Absorption Lines in the Spectra of Active Galactic Nuclei
• Sparsity and adaptivity for the blind separation of partially correlated sources
• Xmm-Newton Observations of the Diffuse X-ray Background
• A disk-dominated and clumpy circumgalactic medium of the Milky Way seen in X-ray emission
• Abundance and temperature of the outer hot circum-Galactic medium: The SRG/eROSITA view of the soft X-ray background in the eFEDS field
• Limits on Hot Galactic Halo Gas from X-ray Absorption Lines
• HaloSat -- A CubeSat to Study the Hot Galactic Halo
• Widespread Detection of Two Components in the Hot Circumgalactic Medium of the Milky Way
• A new 3D solar wind speed and density model based on interplanetary scintillation
• Far UV and Optical Emissions from Three Very Large Supernova Remnants Located at Unusually High Galactic Latitudes
• Thermal and chemical properties of the eROSITA bubbles from Suzaku observations
• A novel method for component separation of extended sources in X-ray astronomy
• On the distance to the North Polar Spur and the local CO-H2 factor
• SRG/eROSITA X-ray shadowing study of giant molecular clouds
• High Resolution X-ray Spectroscopy of the Local Hot Gas along the 3C 273 Sightline
• X-ray analysis of JWST's first galaxy cluster lens SMACS J0723.3-7327
• Kompaneets Model Fitting of the Orion-Eridanus Superbubble II: Thinking Outside of Barnard's Loop
• Numerical studies on the link between radioisotopic signatures on Earth and the formation of the Local Bubble. II. Advanced modeling of interstellar 26Al, 53Mn, 60Fe, and 244Pu influxes as traces of past supernovae in the solar neighborhood
• XMM-Newton view of the N 206 superbubble in the Large Magellanic Cloud
• The SRG/eROSITA All-Sky Survey: SRG/eROSITA cross-calibration with Chandra and XMM-Newton using galaxy cluster gas temperatures
• Suzaku and XMM-Newton Observations of the North Polar Spur: Charge Exchange or ISM Absorption?
• Three-dimensional morphological asymmetries in the ejecta of Cassiopeia A using a component separation method in X-rays
• Observed Limits on Charge Exchange Contributions to the Diffuse X-ray Background
• Asymmetric eROSITA bubbles as the evidence of a circumgalactic medium wind
• disnht: modeling X-ray absorption from distributed column densities
• 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
• Semi-Blind Source Separation with Learned Constraints
• The X-ray synchrotron rims in Cassiopeia A narrow with energy
• Discovery of the Goat Horn complex: a $\sim 1000$ deg${}^2$ diffuse X-ray source connected to radio loop XII
• A new understanding of the Gemini-Monoceros X-ray enhancement from discoveries with eROSITA

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• Studying the multi-phase interstellar medium in the Large Magellanic Cloud with SRG/eROSITA -- I. Analysis of diffuse X-ray emission
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