Improved Constraints on the Faraday Rotation toward Eight Fast Radio Bursts Using Dense Grids of Polarized Radio Galaxies
We present 2–4 GHz observations of polarized radio galaxies toward eight fast radio bursts (FRBs), producing grids of Faraday rotation measure (RM) sources with sky densities of 9–28 polarized sources per square degree. Using a Bayesian interpolation framework, we constrain Galactic RM fluctuations...
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2025-01-01
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| author | Ayush Pandhi B. M. Gaensler Ziggy Pleunis Sebastian Hutschenreuter Casey Law Ryan Mckinven Shane P. O’Sullivan Emily B. Petroff Tessa Vernstrom |
| author_facet | Ayush Pandhi B. M. Gaensler Ziggy Pleunis Sebastian Hutschenreuter Casey Law Ryan Mckinven Shane P. O’Sullivan Emily B. Petroff Tessa Vernstrom |
| author_sort | Ayush Pandhi |
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| description | We present 2–4 GHz observations of polarized radio galaxies toward eight fast radio bursts (FRBs), producing grids of Faraday rotation measure (RM) sources with sky densities of 9–28 polarized sources per square degree. Using a Bayesian interpolation framework, we constrain Galactic RM fluctuations below ∼1 deg ^2 angular scales around the FRB positions. Despite the positions of all eight FRBs being located far from the Galactic plane, we constrain previously unresolved small-scale Galactic RM structures around six of the eight FRBs. In two of these fields, we find potential changes in the sign of the Galactic RM that are not captured by previous, sparsely sampled RM grid observations. Our Galactic RM estimate toward the FRBs differs by a few radians per square meter up to ∼40 rad m ^−2 from the all-sky Galactic RM map of S. Hutschenreuter et al. Extrapolating our results to the known population of polarized FRB sources, we may be incorrectly interpreting the host galaxy RM for ∼30% of the FRB source population with current RM grid observations. Measuring small-scale Galactic RM variations is crucial for identifying FRBs in low-density and weakly magnetized environments, which in turn could serve as potent probes of cosmic magnetism. This framework of reconstructing continuous Galactic RM structure from RM grid observations can be readily applied to FRBs that fall within the sky coverage of upcoming large-sky radio polarization surveys of radio galaxies, such as the Very Large Array Sky Survey and the Polarization Sky Survey of the Universe’s Magnetism. |
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| institution | Kabale University |
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| language | English |
| publishDate | 2025-01-01 |
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| series | The Astrophysical Journal |
| spelling | doaj-art-fffc57d1a4d04481b381dfbba56f6d882025-08-20T03:40:18ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01982214610.3847/1538-4357/adb8e3Improved Constraints on the Faraday Rotation toward Eight Fast Radio Bursts Using Dense Grids of Polarized Radio GalaxiesAyush Pandhi0https://orcid.org/0000-0002-8897-1973B. M. Gaensler1https://orcid.org/0000-0002-3382-9558Ziggy Pleunis2https://orcid.org/0000-0002-4795-697XSebastian Hutschenreuter3https://orcid.org/0000-0002-6952-9688Casey Law4https://orcid.org/0000-0002-4119-9963Ryan Mckinven5https://orcid.org/0000-0001-7348-6900Shane P. O’Sullivan6https://orcid.org/0000-0002-3968-3051Emily B. Petroff7https://orcid.org/0000-0002-9822-8008Tessa Vernstrom8https://orcid.org/0000-0001-7093-3875David A. Dunlap Department of Astronomy and Astrophysics, University of Toronto , 50 St. George Street, Toronto, ON M5S 3H4, Canada ; ayush.pandhi@astro.utoronto.ca; Dunlap Institute for Astronomy and Astrophysics, University of Toronto , 50 St. George Street, Toronto, ON M5S 3H4, CanadaDavid A. Dunlap Department of Astronomy and Astrophysics, University of Toronto , 50 St. George Street, Toronto, ON M5S 3H4, Canada ; ayush.pandhi@astro.utoronto.ca; Dunlap Institute for Astronomy and Astrophysics, University of Toronto , 50 St. George Street, Toronto, ON M5S 3H4, Canada; Department of Astronomy and Astrophysics, 1156 High Street, University of California Santa Cruz , Santa Cruz, CA 95064, USAAnton Pannekoek Institute for Astronomy, University of Amsterdam , Science Park 904, 1098 XH Amsterdam, The Netherlands; ASTRON, Netherlands Institute for Radio Astronomy , Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The NetherlandsDepartment of Astrophysics, University of Vienna , Türkenschanzstrasse 17, 1180 Vienna, AustriaCahill Center for Astronomy and Astrophysics , MC 249-17, California Institute of Technology, Pasadena, CA 91125, USA; Owens Valley Radio Observatory, California Institute of Technology , Big Pine, CA 93513, USADepartment of Physics, McGill University , 3600 rue University, Montreal, QC H3A 2T8, Canada; Trottier Space Institute, McGill University , 3550 rue University, Montreal, QC H3A 2A7, CanadaDepartamento de Física de la Tierra y Astrofísica & IPARCOS-UCM, Universidad Complutense de Madrid , E-28040 Madrid, SpainPerimeter Institute for Theoretical Physics , 31 Caroline Street, Waterloo, ON N2L 2Y5, CanadaCSIRO , Space and Astronomy, P.O. Box 1130, Bentley, WA 6102, Australia; ICRAR, The University of Western Australia , 35 Stirling Highway, Crawley, WA 6009, AustraliaWe present 2–4 GHz observations of polarized radio galaxies toward eight fast radio bursts (FRBs), producing grids of Faraday rotation measure (RM) sources with sky densities of 9–28 polarized sources per square degree. Using a Bayesian interpolation framework, we constrain Galactic RM fluctuations below ∼1 deg ^2 angular scales around the FRB positions. Despite the positions of all eight FRBs being located far from the Galactic plane, we constrain previously unresolved small-scale Galactic RM structures around six of the eight FRBs. In two of these fields, we find potential changes in the sign of the Galactic RM that are not captured by previous, sparsely sampled RM grid observations. Our Galactic RM estimate toward the FRBs differs by a few radians per square meter up to ∼40 rad m ^−2 from the all-sky Galactic RM map of S. Hutschenreuter et al. Extrapolating our results to the known population of polarized FRB sources, we may be incorrectly interpreting the host galaxy RM for ∼30% of the FRB source population with current RM grid observations. Measuring small-scale Galactic RM variations is crucial for identifying FRBs in low-density and weakly magnetized environments, which in turn could serve as potent probes of cosmic magnetism. This framework of reconstructing continuous Galactic RM structure from RM grid observations can be readily applied to FRBs that fall within the sky coverage of upcoming large-sky radio polarization surveys of radio galaxies, such as the Very Large Array Sky Survey and the Polarization Sky Survey of the Universe’s Magnetism.https://doi.org/10.3847/1538-4357/adb8e3Radio burstsMilky Way magnetic fieldsPolarimetry |
| spellingShingle | Ayush Pandhi B. M. Gaensler Ziggy Pleunis Sebastian Hutschenreuter Casey Law Ryan Mckinven Shane P. O’Sullivan Emily B. Petroff Tessa Vernstrom Improved Constraints on the Faraday Rotation toward Eight Fast Radio Bursts Using Dense Grids of Polarized Radio Galaxies The Astrophysical Journal Radio bursts Milky Way magnetic fields Polarimetry |
| title | Improved Constraints on the Faraday Rotation toward Eight Fast Radio Bursts Using Dense Grids of Polarized Radio Galaxies |
| title_full | Improved Constraints on the Faraday Rotation toward Eight Fast Radio Bursts Using Dense Grids of Polarized Radio Galaxies |
| title_fullStr | Improved Constraints on the Faraday Rotation toward Eight Fast Radio Bursts Using Dense Grids of Polarized Radio Galaxies |
| title_full_unstemmed | Improved Constraints on the Faraday Rotation toward Eight Fast Radio Bursts Using Dense Grids of Polarized Radio Galaxies |
| title_short | Improved Constraints on the Faraday Rotation toward Eight Fast Radio Bursts Using Dense Grids of Polarized Radio Galaxies |
| title_sort | improved constraints on the faraday rotation toward eight fast radio bursts using dense grids of polarized radio galaxies |
| topic | Radio bursts Milky Way magnetic fields Polarimetry |
| url | https://doi.org/10.3847/1538-4357/adb8e3 |
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