What Rogue Hydrogen Clouds Tell Us about Galactic Magnetic Fields
Observations of the Milky Way and external galaxies support the idea that large-scale magnetic fields are concentrated in galactic disks, with halo magnetic fields at least an order of magnitude weaker. However, very little is known about the transition between the two. We present the discovery of l...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/ad9338 |
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| author | Bailey M. Forster Tyler J. Foster Roland Kothes Alex S. Hill Jo-Anne C. Brown |
| author_facet | Bailey M. Forster Tyler J. Foster Roland Kothes Alex S. Hill Jo-Anne C. Brown |
| author_sort | Bailey M. Forster |
| collection | DOAJ |
| description | Observations of the Milky Way and external galaxies support the idea that large-scale magnetic fields are concentrated in galactic disks, with halo magnetic fields at least an order of magnitude weaker. However, very little is known about the transition between the two. We present the discovery of linearly polarized radio emission at the interface between interacting shells of gas within a well-known grouping of high-velocity clouds (HVCs), the anticenter shell. Faraday rotation of diffuse emission and of background extragalactic compact sources demonstrates an enhancement of the field at the interface. This is the clearest observed example of an HVC altering the large-scale magnetic field at the disk–halo interface and is the first image of magnetic field effects in an HVC. These results demonstrate the possibility of future three-dimensional reconstruction of the Galactic magnetic field and showcase the versatility of the Synthesis Telescope at the Dominion Radio Astrophysical Observatory as one of the few existing telescopes that can exploit this new method of probing Galactic magnetism. |
| format | Article |
| id | doaj-art-ab8b73f56989476d926f101ee7b82acb |
| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj-art-ab8b73f56989476d926f101ee7b82acb2025-01-25T04:55:23ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01979217710.3847/1538-4357/ad9338What Rogue Hydrogen Clouds Tell Us about Galactic Magnetic FieldsBailey M. Forster0Tyler J. Foster1https://orcid.org/0000-0002-3189-4882Roland Kothes2https://orcid.org/0000-0001-5953-0100Alex S. Hill3https://orcid.org/0000-0001-7301-5666Jo-Anne C. Brown4https://orcid.org/0000-0003-4781-5701Department of Physics & Astronomy, Brandon University , Brandon, MB, Canada ; FosterT@BrandonU.CA; National Research Council Canada , Herzberg Astronomy and Astrophysics, Dominion Radio Astrophysical Observatory, Kaleden, BC, Canada; Department of Physics, McGill University , Montreal, QC, CanadaDepartment of Physics & Astronomy, Brandon University , Brandon, MB, Canada ; FosterT@BrandonU.CANational Research Council Canada , Herzberg Astronomy and Astrophysics, Dominion Radio Astrophysical Observatory, Kaleden, BC, CanadaNational Research Council Canada , Herzberg Astronomy and Astrophysics, Dominion Radio Astrophysical Observatory, Kaleden, BC, Canada; Department of Computer Science, Math, Physics, & Statistics, University of British Columbia , Kelowna, BC, CanadaDepartment of Physics & Astronomy, University of Calgary , Calgary, AB, CanadaObservations of the Milky Way and external galaxies support the idea that large-scale magnetic fields are concentrated in galactic disks, with halo magnetic fields at least an order of magnitude weaker. However, very little is known about the transition between the two. We present the discovery of linearly polarized radio emission at the interface between interacting shells of gas within a well-known grouping of high-velocity clouds (HVCs), the anticenter shell. Faraday rotation of diffuse emission and of background extragalactic compact sources demonstrates an enhancement of the field at the interface. This is the clearest observed example of an HVC altering the large-scale magnetic field at the disk–halo interface and is the first image of magnetic field effects in an HVC. These results demonstrate the possibility of future three-dimensional reconstruction of the Galactic magnetic field and showcase the versatility of the Synthesis Telescope at the Dominion Radio Astrophysical Observatory as one of the few existing telescopes that can exploit this new method of probing Galactic magnetism.https://doi.org/10.3847/1538-4357/ad9338Interstellar magnetic fieldsInterstellar mediumInterstellar cloudsHigh-velocity clouds |
| spellingShingle | Bailey M. Forster Tyler J. Foster Roland Kothes Alex S. Hill Jo-Anne C. Brown What Rogue Hydrogen Clouds Tell Us about Galactic Magnetic Fields The Astrophysical Journal Interstellar magnetic fields Interstellar medium Interstellar clouds High-velocity clouds |
| title | What Rogue Hydrogen Clouds Tell Us about Galactic Magnetic Fields |
| title_full | What Rogue Hydrogen Clouds Tell Us about Galactic Magnetic Fields |
| title_fullStr | What Rogue Hydrogen Clouds Tell Us about Galactic Magnetic Fields |
| title_full_unstemmed | What Rogue Hydrogen Clouds Tell Us about Galactic Magnetic Fields |
| title_short | What Rogue Hydrogen Clouds Tell Us about Galactic Magnetic Fields |
| title_sort | what rogue hydrogen clouds tell us about galactic magnetic fields |
| topic | Interstellar magnetic fields Interstellar medium Interstellar clouds High-velocity clouds |
| url | https://doi.org/10.3847/1538-4357/ad9338 |
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