An Explanation for Non-Power-law Behavior in the Hard X-ray Spectrum of the July 23, 2002 Solar |
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Eduard Kontar Submitted: 2003-03-26 14:51
High-resolution RHESSI data reveal that solar flare hard X-ray spectra show systematic deviations from power-law behavior. Even for injection of a power-law
electron spectrum, such deviations are expected because of a number of effects, including
nonuniform target ionization and solar albedo backscattering of the primary hard X-ray flux. In this paper we examine 1 keV resolution hard X-ray spectra for
the intense July 23, 2002 event, corrected for the effects of decimation, pulse pile-up and background. We find that the observed spectra indeed deviate from a power-law behavior in a manner consistent with the effects of nonuniform target ionization. Further, this interpretation
of the observed deviations requires that the amount of coronal material increases during the initial
phase of the flare. The implications of this discovery for models of atmospheric response to flare heating are discussed.
Authors: E.P. Kontar, J.C. Brown, A.G. Emslie, R.A. Schwartz, D.M. Smith, and R.C. Alexander
Projects:
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Publication Status: ApJ Letters (in press)
Last Modified: 2003-03-26 14:51
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