Energetic gamma-ray emission from solar flares

Abstract

Recent advances in the $\gamma$-ray observations of solar flares by the \textit{Fermi} satellite, demand revisions in the hadronic $\gamma$-ray flux computation below 1 GeV. In this work we utilize recently updated pion production cross sections, along with an accurate description of low energy nuclear interactions. Applying these new interaction descriptions to model the \textit{Fermi} Large Area Telescope (LAT) solar flare data, we infer the primary particle spectral parameters. Application of this new cross section description leads to significantly different spectral parameters compared to those obtained previously. Furthermore, the inclusion of nuclei in these calculations leads to a primary spectrum that is generally harder than that required from proton only considerations. Lastly, the flare data at lower MeV energies, detected by the \textit{Fermi} Gamma-ray Burst Monitor (GBM), is demonstrated to provide additional low-energy spectral information.

11 pages, 9 figures, ApJ

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• Role of magnetic arcades in explaining the puzzle of the gamma-ray emission from the solar disk
• Modeling Hadronic Gamma-ray Emissions from Solar Flares and Prospects for Detecting Non-thermal Signatures from Protostars
• Gamma-ray emission in proton-induced nuclear reactions on natC and Mylar targets over the incident energy range of Ep = 30-200 MeV. Astrophysical implications