Simulating gamma-ray production from cosmic rays interacting with the solar atmosphere in the presence of coronal magnetic fields

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Hauptverfasser: Li, Zhe, Ng, Kenny C. Y., Chen, Songzhan, Nan, Yuncheng, He, Huihai
Format: Preprint
Veröffentlicht: 2020
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author Li, Zhe
Ng, Kenny C. Y.
Chen, Songzhan
Nan, Yuncheng
He, Huihai
author_facet Li, Zhe
Ng, Kenny C. Y.
Chen, Songzhan
Nan, Yuncheng
He, Huihai
contents Cosmic rays can interact with the solar atmosphere and produce a slew of secondary messengers, making the Sun a bright gamma-ray source in the sky. Detailed observations with Fermi-LAT have shown that these interactions must be strongly affected by solar magnetic fields in order to produce the wide range of observational features, such as high flux and hard spectrum. However, the detailed mechanisms behind these features are still a mystery. In this work, we tackle this problem by performing particle interaction simulations in the solar atmosphere in the presence of coronal magnetic fields modelled using the potential field source surface (PFSS) model. We find that the low-energy (~GeV) gamma-ray production is significantly enhanced by the coronal magnetic fields, but the enhancement decreases rapidly with energy. The enhancement is directly correlated with the production of gamma rays with large deviation angles relative to the input cosmic-ray direction. We conclude that coronal magnetic fields are essential for correctly modeling solar disk gamma rays below 10GeV, but above that the effect of coronal magnetic fields diminishes. Other magnetic field structures are needed to explain the high-energy disk emission.
format Preprint
id arxiv_https___arxiv_org_abs_2009_03888
institution arXiv
publishDate 2020
record_format arxiv
spellingShingle Simulating gamma-ray production from cosmic rays interacting with the solar atmosphere in the presence of coronal magnetic fields
Li, Zhe
Ng, Kenny C. Y.
Chen, Songzhan
Nan, Yuncheng
He, Huihai
High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
Cosmic rays can interact with the solar atmosphere and produce a slew of secondary messengers, making the Sun a bright gamma-ray source in the sky. Detailed observations with Fermi-LAT have shown that these interactions must be strongly affected by solar magnetic fields in order to produce the wide range of observational features, such as high flux and hard spectrum. However, the detailed mechanisms behind these features are still a mystery. In this work, we tackle this problem by performing particle interaction simulations in the solar atmosphere in the presence of coronal magnetic fields modelled using the potential field source surface (PFSS) model. We find that the low-energy (~GeV) gamma-ray production is significantly enhanced by the coronal magnetic fields, but the enhancement decreases rapidly with energy. The enhancement is directly correlated with the production of gamma rays with large deviation angles relative to the input cosmic-ray direction. We conclude that coronal magnetic fields are essential for correctly modeling solar disk gamma rays below 10GeV, but above that the effect of coronal magnetic fields diminishes. Other magnetic field structures are needed to explain the high-energy disk emission.
title Simulating gamma-ray production from cosmic rays interacting with the solar atmosphere in the presence of coronal magnetic fields
topic High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2009.03888