The Large-scale Anisotropy and Flux (de)magnification of Ultrahigh-energy Cosmic Rays in the Galactic Magnetic Field
We calculate the arrival direction distribution of ultrahigh-energy cosmic rays (UHECRs) with a new suite of models of the Galactic magnetic field (GMF), assuming sources follow the large-scale structure of the Universe. Compared to previous GMF models, the amplitude of the dipole component of the U...
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IOP Publishing
2024-01-01
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| Series: | The Astrophysical Journal Letters |
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| Online Access: | https://doi.org/10.3847/2041-8213/ad856f |
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| author | Teresa Bister Glennys R. Farrar Michael Unger |
| author_facet | Teresa Bister Glennys R. Farrar Michael Unger |
| author_sort | Teresa Bister |
| collection | DOAJ |
| description | We calculate the arrival direction distribution of ultrahigh-energy cosmic rays (UHECRs) with a new suite of models of the Galactic magnetic field (GMF), assuming sources follow the large-scale structure of the Universe. Compared to previous GMF models, the amplitude of the dipole component of the UHECR arrival flux is significantly reduced. We find that the reduction is due to the accidentally coinciding position of the peak of the extragalactic UHECR flux and the boundary of strong flux demagnification due to the GMF toward the central region of the Galaxy. This serendipitous sensitivity of UHECR anisotropies to the GMF model will be a powerful probe of the source distribution as well as Galactic and extragalactic magnetic fields. Demagnification by the GMF also impacts the visibility of some popular source candidates. |
| format | Article |
| id | doaj-art-36b9bd19df5a4de3bd5f2cfeada7e528 |
| institution | OA Journals |
| issn | 2041-8205 |
| language | English |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal Letters |
| spelling | doaj-art-36b9bd19df5a4de3bd5f2cfeada7e5282025-08-20T02:18:47ZengIOP PublishingThe Astrophysical Journal Letters2041-82052024-01-019751L2110.3847/2041-8213/ad856fThe Large-scale Anisotropy and Flux (de)magnification of Ultrahigh-energy Cosmic Rays in the Galactic Magnetic FieldTeresa Bister0https://orcid.org/0000-0003-4005-0857Glennys R. Farrar1https://orcid.org/0000-0003-2417-5975Michael Unger2https://orcid.org/0000-0002-7651-0272Institute for Mathematics, Astrophysics and Particle Physics, Radboud University Nijmegen , Nijmegen, The Netherlands ; teresa.bister@ru.nl; Nationaal Instituut voor Subatomaire Fysica (NIKHEF) , Science Park, Amsterdam, The NetherlandsCenter for Cosmology and Particle Physics, New York University , New York, NY 10003, USA ; gf25@nyu.eduInstitute for Astroparticle Physics , Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany ; michael.unger@kit.edu; Institutt for fysikk, Norwegian University of Science and Technology (NTNU) , Trondheim, NorwayWe calculate the arrival direction distribution of ultrahigh-energy cosmic rays (UHECRs) with a new suite of models of the Galactic magnetic field (GMF), assuming sources follow the large-scale structure of the Universe. Compared to previous GMF models, the amplitude of the dipole component of the UHECR arrival flux is significantly reduced. We find that the reduction is due to the accidentally coinciding position of the peak of the extragalactic UHECR flux and the boundary of strong flux demagnification due to the GMF toward the central region of the Galaxy. This serendipitous sensitivity of UHECR anisotropies to the GMF model will be a powerful probe of the source distribution as well as Galactic and extragalactic magnetic fields. Demagnification by the GMF also impacts the visibility of some popular source candidates.https://doi.org/10.3847/2041-8213/ad856fCosmic ray astronomyCosmic raysCosmic ray sourcesExtragalactic magnetic fieldsMilky Way magnetic fieldsUltra-high-energy cosmic radiation |
| spellingShingle | Teresa Bister Glennys R. Farrar Michael Unger The Large-scale Anisotropy and Flux (de)magnification of Ultrahigh-energy Cosmic Rays in the Galactic Magnetic Field The Astrophysical Journal Letters Cosmic ray astronomy Cosmic rays Cosmic ray sources Extragalactic magnetic fields Milky Way magnetic fields Ultra-high-energy cosmic radiation |
| title | The Large-scale Anisotropy and Flux (de)magnification of Ultrahigh-energy Cosmic Rays in the Galactic Magnetic Field |
| title_full | The Large-scale Anisotropy and Flux (de)magnification of Ultrahigh-energy Cosmic Rays in the Galactic Magnetic Field |
| title_fullStr | The Large-scale Anisotropy and Flux (de)magnification of Ultrahigh-energy Cosmic Rays in the Galactic Magnetic Field |
| title_full_unstemmed | The Large-scale Anisotropy and Flux (de)magnification of Ultrahigh-energy Cosmic Rays in the Galactic Magnetic Field |
| title_short | The Large-scale Anisotropy and Flux (de)magnification of Ultrahigh-energy Cosmic Rays in the Galactic Magnetic Field |
| title_sort | large scale anisotropy and flux de magnification of ultrahigh energy cosmic rays in the galactic magnetic field |
| topic | Cosmic ray astronomy Cosmic rays Cosmic ray sources Extragalactic magnetic fields Milky Way magnetic fields Ultra-high-energy cosmic radiation |
| url | https://doi.org/10.3847/2041-8213/ad856f |
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