Publication Date:
2019-11-08
Description:
Little is known about the origin of the high-energy and sustained emission from solar long-duration gamma-ray ares (LDGRFs) identied with the Compton Gamma Ray Observatory, the Solar Maximum Mission, and now Fermi. Though the Fermi Large Area Telescope (LAT) has identied dozens of ares with LDGRF signatures, the nature of this phenomenon has been a challenge to explain due to both extreme energies and long durations. The highest-energy emission has generally been attributed to pion production from the interaction of 300 MeV protons with the ambient matter. The extended duration suggests that particle acceleration occurs over large volumes extending high in the corona, either from stochastic acceleration within large coronal loops or from back precipitation from coronal mass ejectiondriven shocks. It is possible to test these models by making a direct comparison between the properties of the accelerated ion population producing the -ray emission derived from the Fermi/LAT observations and the characteristics of solar energetic particles (SEPs) measured by the Payload for Matter-Antimatter Exploration and Light Nuclei Astrophysics spacecraft in the energy range corresponding to the pion-related emission detected with Fermi. For 14 of these events, we compare the two populationsSEPs in space and the interacting particles at the Sunand discuss the implications in terms of potential sources. Our analysis shows that the two proton numbers are poorly correlated, with their ratio spanning more than 5 orders of magnitude, suggesting that the back precipitation of shock-acceleration particles is unlikely to be the source of the F emission.
Keywords:
Solar Physics
Type:
GSFC-E-DAA-TN73643
,
The Astrophysical Journal (ISSN 0004-637X) (e-ISSN 1538-4357); 879; 2; 90
Format:
text
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