Angular Power Spectrum of TeV–PeV Cosmic-Ray Anisotropies
Simulations of the cosmic-ray (CR) anisotropy down to TeV energies are presented, using turbulence parameters consistent with those inferred from observations of the interstellar medium. We compute the angular power spectra C _ℓ of the CR anisotropy obtained from the simulations. We demonstrate that...
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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/ada441 |
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| author | Wenyi Bian Gwenael Giacinti Brian Reville |
| author_facet | Wenyi Bian Gwenael Giacinti Brian Reville |
| author_sort | Wenyi Bian |
| collection | DOAJ |
| description | Simulations of the cosmic-ray (CR) anisotropy down to TeV energies are presented, using turbulence parameters consistent with those inferred from observations of the interstellar medium. We compute the angular power spectra C _ℓ of the CR anisotropy obtained from the simulations. We demonstrate that the amplitude of the large-scale gradient in the CR density profile affects only the overall normalization of the C _ℓ values, without affecting the shape of the angular power spectrum. We show that the power spectrum depends on CR energy and that it is sensitive to the location of the observer at small ℓ . It is found to flatten at large ℓ and can be modeled by a broken power law, exhibiting a break at ℓ ≈ 4. Our computed power spectrum at ~10 TeV fits well HAWC and IceCube measurements. Moreover, we calculate all coefficients of the spherical harmonics and compute the component of the angular power spectrum projected onto the direction of the local magnetic field line. We find that deviations from gyrotropy become increasingly important at higher CR energies and larger values of ℓ . |
| format | Article |
| id | doaj-art-63ab75b2bd364d1483701265e36c3ad0 |
| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
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| series | The Astrophysical Journal |
| spelling | doaj-art-63ab75b2bd364d1483701265e36c3ad02025-01-28T06:22:52ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01979219710.3847/1538-4357/ada441Angular Power Spectrum of TeV–PeV Cosmic-Ray AnisotropiesWenyi Bian0https://orcid.org/0009-0003-1164-8945Gwenael Giacinti1https://orcid.org/0000-0001-9745-5738Brian Reville2https://orcid.org/0000-0002-3778-1432Tsung-Dao Lee Institute, Shanghai Jiao Tong University , Shanghai 201210, People’s Republic of China ; bianwenyi@sjtu.edu.cn, gwenael.giacinti@sjtu.edu.cn; School of Physics and Astronomy, Shanghai Jiao Tong University , Shanghai 200240, People’s Republic of ChinaTsung-Dao Lee Institute, Shanghai Jiao Tong University , Shanghai 201210, People’s Republic of China ; bianwenyi@sjtu.edu.cn, gwenael.giacinti@sjtu.edu.cn; School of Physics and Astronomy, Shanghai Jiao Tong University , Shanghai 200240, People’s Republic of China; Key Laboratory for Particle Physics , Astrophysics and Cosmology (Ministry of Education) & Shanghai Key Laboratory for Particle Physics and Cosmology, Shanghai 200240, People’s Republic of ChinaMax-Planck-Institut für Kernphysik , Postfach 103980, 69029 Heidelberg, GermanySimulations of the cosmic-ray (CR) anisotropy down to TeV energies are presented, using turbulence parameters consistent with those inferred from observations of the interstellar medium. We compute the angular power spectra C _ℓ of the CR anisotropy obtained from the simulations. We demonstrate that the amplitude of the large-scale gradient in the CR density profile affects only the overall normalization of the C _ℓ values, without affecting the shape of the angular power spectrum. We show that the power spectrum depends on CR energy and that it is sensitive to the location of the observer at small ℓ . It is found to flatten at large ℓ and can be modeled by a broken power law, exhibiting a break at ℓ ≈ 4. Our computed power spectrum at ~10 TeV fits well HAWC and IceCube measurements. Moreover, we calculate all coefficients of the spherical harmonics and compute the component of the angular power spectrum projected onto the direction of the local magnetic field line. We find that deviations from gyrotropy become increasingly important at higher CR energies and larger values of ℓ .https://doi.org/10.3847/1538-4357/ada441Galactic cosmic rays |
| spellingShingle | Wenyi Bian Gwenael Giacinti Brian Reville Angular Power Spectrum of TeV–PeV Cosmic-Ray Anisotropies The Astrophysical Journal Galactic cosmic rays |
| title | Angular Power Spectrum of TeV–PeV Cosmic-Ray Anisotropies |
| title_full | Angular Power Spectrum of TeV–PeV Cosmic-Ray Anisotropies |
| title_fullStr | Angular Power Spectrum of TeV–PeV Cosmic-Ray Anisotropies |
| title_full_unstemmed | Angular Power Spectrum of TeV–PeV Cosmic-Ray Anisotropies |
| title_short | Angular Power Spectrum of TeV–PeV Cosmic-Ray Anisotropies |
| title_sort | angular power spectrum of tev pev cosmic ray anisotropies |
| topic | Galactic cosmic rays |
| url | https://doi.org/10.3847/1538-4357/ada441 |
| work_keys_str_mv | AT wenyibian angularpowerspectrumoftevpevcosmicrayanisotropies AT gwenaelgiacinti angularpowerspectrumoftevpevcosmicrayanisotropies AT brianreville angularpowerspectrumoftevpevcosmicrayanisotropies |