The warm-hot circumgalactic medium of the Milky Way as seen by eROSITA
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| Main Authors: | , , , , , , , , , |
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| Format: | Preprint |
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2023
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| _version_ | 1866909080352718848 |
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| author | Locatelli, N. Ponti, G. Zheng, X. Merloni, A. Becker, W. Comparat, J. Dennerl, K. Freyberg, M. J. Sasaki, M. Yeung, M. C. H. |
| author_facet | Locatelli, N. Ponti, G. Zheng, X. Merloni, A. Becker, W. Comparat, J. Dennerl, K. Freyberg, M. J. Sasaki, M. Yeung, M. C. H. |
| contents | 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. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2310_10715 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | The warm-hot circumgalactic medium of the Milky Way as seen by eROSITA Locatelli, N. Ponti, G. Zheng, X. Merloni, A. Becker, W. Comparat, J. Dennerl, K. Freyberg, M. J. Sasaki, M. Yeung, M. C. H. Astrophysics of Galaxies 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. |
| title | The warm-hot circumgalactic medium of the Milky Way as seen by eROSITA |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2310.10715 |