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| Main Authors: | , |
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| Format: | Preprint |
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2025
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| Online Access: | https://arxiv.org/abs/2506.02799 |
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| _version_ | 1866909635012722688 |
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| author | Maji, Debangan Roy, Subhashis |
| author_facet | Maji, Debangan Roy, Subhashis |
| contents | Using archival data, we have made an HI absorption study of the 7$^\prime$ halo surrounding the Sgr A complex, observed towards the Galactic centre (GC) region. We find strong HI absorption near velocities of $-$53 km s$^{-1}$, which is due to the 3-kpc arm, placing it beyond 5 kpc from us. We further examined the HI absorption properties towards 5 different parts of the 7$^\prime$ halo. Absorption by +50 km s$^{-1}$ GC cloud is seen towards only 3 parts of the halo, but not towards the other 2 regions. Strong emissions in CO and CS are, however, identified toward all the above 5 parts of the halo by the +50 km s$^{-1}$ GC molecular cloud. This does show that the 7$^\prime$ halo is partly behind, and partly in front of the +50 km s$^{-1}$ cloud. To our knowledge, this, for the first time clearly shows the 7$^\prime$ halo to be located at the same distance as the +50 km s$^{-1}$ molecular cloud, i.e., at the GC region. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2506_02799 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Distance to the Galactic centre 7$^\prime$ halo from HI absorption Maji, Debangan Roy, Subhashis Astrophysics of Galaxies Using archival data, we have made an HI absorption study of the 7$^\prime$ halo surrounding the Sgr A complex, observed towards the Galactic centre (GC) region. We find strong HI absorption near velocities of $-$53 km s$^{-1}$, which is due to the 3-kpc arm, placing it beyond 5 kpc from us. We further examined the HI absorption properties towards 5 different parts of the 7$^\prime$ halo. Absorption by +50 km s$^{-1}$ GC cloud is seen towards only 3 parts of the halo, but not towards the other 2 regions. Strong emissions in CO and CS are, however, identified toward all the above 5 parts of the halo by the +50 km s$^{-1}$ GC molecular cloud. This does show that the 7$^\prime$ halo is partly behind, and partly in front of the +50 km s$^{-1}$ cloud. To our knowledge, this, for the first time clearly shows the 7$^\prime$ halo to be located at the same distance as the +50 km s$^{-1}$ molecular cloud, i.e., at the GC region. |
| title | Distance to the Galactic centre 7$^\prime$ halo from HI absorption |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2506.02799 |