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R. J. Murphy, G. H. Share (Naval Resarch Laboratory), B. Kozlovsky (Tel Aviv University), X.-M. Hua (Emergent Technology Services Inc.)
Neutron and gamma-ray data from the 1991 June 4 and 11 solar flares observed by CGRO/OSSE are used to explore the time variation of the accelerated-particle spectra. Because of the strong dependence of neutron production on the steepness of the energetic particle spectrum, neutron observations can reveal variations of the spectral index too subtle to be detected with observations of gamma-ray lines alone. We show that theoretical calculations of neutron and gamma-ray production provide a self-consistent understanding of these processes and that the combination of data is consistent with a power law spectral shape for particles accelerated in solar flares. For the June 4 flare in particular, the power-law index is unchanged across 2 orders of magnitude of particle energy, from a few MeV to a few hundred MeV. In both flares, the spectra hardened as the flares progressed, with a change in spectral index by as much as 1. Neutron data analyzed previously from two flares observed by SMM are reassessed and, using a revised SMM neutron response function, are also shown to be consistent with a power-law energetic-particle spectrum. This research was supported in part by NASA W19977.
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The author(s) of this abstract have provided an email address for comments about the abstract: murphy@gamma.nrl.navy.mil
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.