The impact of Solar magnetic field configurations on the production of gamma rays at the Solar disk

Fuente: arXiv
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Autores principales: Dörner, Julien, Effenberger, Frederic, Fichtner, Horst, Tjus, Julia Becker, Jin, Meng, Liu, Wei, Petrosian, Vahe'
Formato: Preprint
Publicado: 2025
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author Dörner, Julien
Effenberger, Frederic
Fichtner, Horst
Tjus, Julia Becker
Jin, Meng
Liu, Wei
Petrosian, Vahe'
author_facet Dörner, Julien
Effenberger, Frederic
Fichtner, Horst
Tjus, Julia Becker
Jin, Meng
Liu, Wei
Petrosian, Vahe'
contents The Sun produces a steady signal of high-energy gamma rays through interactions of Galactic cosmic rays (GCRs) with its atmosphere. Observations with Fermi-LAT and HAWC have revealed a gamma-ray flux significantly higher than early theoretical predictions, with unexpected temporal and spectral features that suggest a crucial role of the solar magnetic field. In this work, we model GCR-induced gamma-ray emission at the solar disk using the CRPropa framework with realistic hadronic interactions, chromospheric density profiles, and several magnetic field configurations over the solar cycle. This allows us to quantify the gamma-ray emission of the entire solar disk for different phases of the solar activity cycle and we present, for the first time, maps of the production locations of gamma rays on the solar surface. We consider both mono-energetic and realistic power-law injection spectra in a simplified dipole-quadrupole current sheet model and potential-field source surface (PFSS) extrapolations for Carrington rotations during solar maximum and minimum. Our results show that magnetic mirroring and large-scale field topology strongly affect the spectral shape and spatial distribution of the emission, with slightly enhanced fluxes predicted at solar minimum. While our simulated baseline fluxes remain below observations, additional effects, such as heavier nuclei, Parker-field mirroring, and deeper atmospheric interactions, could result in further enhancements of fluxes closer to observational values. Hadronic interactions do not only produce gamma rays but also neutrinos. We estimate the expected neutrino flux from the Sun based on our gamma-ray predictions. We find that the expected flux is slightly below current upper limits from IceCube.
format Preprint
id arxiv_https___arxiv_org_abs_2512_01403
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The impact of Solar magnetic field configurations on the production of gamma rays at the Solar disk
Dörner, Julien
Effenberger, Frederic
Fichtner, Horst
Tjus, Julia Becker
Jin, Meng
Liu, Wei
Petrosian, Vahe'
High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
The Sun produces a steady signal of high-energy gamma rays through interactions of Galactic cosmic rays (GCRs) with its atmosphere. Observations with Fermi-LAT and HAWC have revealed a gamma-ray flux significantly higher than early theoretical predictions, with unexpected temporal and spectral features that suggest a crucial role of the solar magnetic field. In this work, we model GCR-induced gamma-ray emission at the solar disk using the CRPropa framework with realistic hadronic interactions, chromospheric density profiles, and several magnetic field configurations over the solar cycle. This allows us to quantify the gamma-ray emission of the entire solar disk for different phases of the solar activity cycle and we present, for the first time, maps of the production locations of gamma rays on the solar surface. We consider both mono-energetic and realistic power-law injection spectra in a simplified dipole-quadrupole current sheet model and potential-field source surface (PFSS) extrapolations for Carrington rotations during solar maximum and minimum. Our results show that magnetic mirroring and large-scale field topology strongly affect the spectral shape and spatial distribution of the emission, with slightly enhanced fluxes predicted at solar minimum. While our simulated baseline fluxes remain below observations, additional effects, such as heavier nuclei, Parker-field mirroring, and deeper atmospheric interactions, could result in further enhancements of fluxes closer to observational values. Hadronic interactions do not only produce gamma rays but also neutrinos. We estimate the expected neutrino flux from the Sun based on our gamma-ray predictions. We find that the expected flux is slightly below current upper limits from IceCube.
title The impact of Solar magnetic field configurations on the production of gamma rays at the Solar disk
topic High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2512.01403