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| Format: | Preprint |
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2024
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| Online Access: | https://arxiv.org/abs/2402.09726 |
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| _version_ | 1866929244274163712 |
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| author | Das, Sanskriti |
| author_facet | Das, Sanskriti |
| contents | We report the first detection of non-thermal broadening of OVII lines in the warm-hot $\approx 10^6$ K circumgalactic medium (CGM) of the Milky Way. We use $z$=0 absorption of OVII K$α$, OVII K$β$, and OVIII K$α$ lines in archival grating data of $b>$15$^\circ$ quasar sightlines from $Chandra$ and $XMM$-$Newton$. Non-thermal line broadening is evident in two-third of the sightlines considered, and on average is constrained at 4.6$σ$ significance. Non-thermal line broadening dominates over thermal broadening. We extensively test whether the appearance of non-thermal line broadening could instead be because of multiple thermally broadened velocity components and robustly rule it out. Non-thermal line broadening is more evident toward sightlines at lower galactic latitude indicating the Galactic disk origin of the nonthermal sources. There is weak/no correlation between non-thermal line broadening and the angular separation of sightlines from the Galactic center, indicating that the nuclear region might not be a major source of non-thermal factors. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2402_09726 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Detecting the effect of non-thermal sources on the warm-hot Galactic halo Das, Sanskriti Astrophysics of Galaxies High Energy Astrophysical Phenomena We report the first detection of non-thermal broadening of OVII lines in the warm-hot $\approx 10^6$ K circumgalactic medium (CGM) of the Milky Way. We use $z$=0 absorption of OVII K$α$, OVII K$β$, and OVIII K$α$ lines in archival grating data of $b>$15$^\circ$ quasar sightlines from $Chandra$ and $XMM$-$Newton$. Non-thermal line broadening is evident in two-third of the sightlines considered, and on average is constrained at 4.6$σ$ significance. Non-thermal line broadening dominates over thermal broadening. We extensively test whether the appearance of non-thermal line broadening could instead be because of multiple thermally broadened velocity components and robustly rule it out. Non-thermal line broadening is more evident toward sightlines at lower galactic latitude indicating the Galactic disk origin of the nonthermal sources. There is weak/no correlation between non-thermal line broadening and the angular separation of sightlines from the Galactic center, indicating that the nuclear region might not be a major source of non-thermal factors. |
| title | Detecting the effect of non-thermal sources on the warm-hot Galactic halo |
| topic | Astrophysics of Galaxies High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2402.09726 |