NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
High-energy gamma-ray emission from solar flares: Constraining the accelerated proton spectrumUsing a multi-component model to describe the gamma-ray emission, we investigate the flares of December 16, 1988 and March 6, 1989 which exhibited unambiguous evidence of neutral pion decay. The observations are then combined with theoretical calculations of pion production to constrain the accelerated proton spectra. The detection of pi(sup 0) emission alone can indicate much about the energy distribution and spectral variation of the protons accelerated to pion producing energies. Here both the intensity and detailed spectral shape of the Doppler-broadened pi(sup 0) decay feature are used to determine the spectral form of the accelerated proton energy distribution. The Doppler width of this gamma-ray emission provides a unique diagnostic of the spectral shape at high energies, independent of any normalisation. To our knowledge, this is the first time that this diagnostic has been used to constrain the proton spectra. The form of the energetic proton distribution is found to be severely limited by the observed intensity and Doppler width of the pi(sup 0) decay emission, demonstrating effectively the diagnostic capabilities of the pi(sup 0) decay gamma-rays. The spectral index derived from the gamma-ray intensity is found to be much harder than that derived from the Doppler width. To reconcile this apparent discrepancy we investigate the effects of introducing a high-energy cut-off in the accelerated proton distribution. With cut-off energies of around 0.5-0.8 GeV and relatively hard spectra, the observed intensities and broadening can be reproduced with a single energetic proton distribution above the pion production threshold.
Document ID
19950029343
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Alexander, David
(Montana State Univ. Bozeman, MT, United States)
Dunphy, Philip P.
(Univ. of New Hampshire, Durham, NH United States)
Mackinnon, Alexander L.
(Univ. of Glasgow Glasgow, United Kingdom)
Date Acquired
August 16, 2013
Publication Date
April 1, 1994
Publication Information
Publication: Solar Physics
Volume: 151
Issue: 1
ISSN: 0038-0938
Subject Category
Solar Physics
Accession Number
95A60942
Funding Number(s)
CONTRACT_GRANT: NAGW-2755
CONTRACT_GRANT: NATO-920832
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available