Comparison of Algorithms for Reconstructing Electron Spectra from Solar Flare Hard X-Ray Spectra
Abstract
The Ramaty High Energy Solar Spectroscopic Imager (RHESSI) is yielding solar flare hard X-ray (HXR) spectra with unprecedented resolution and precision. Such spectra enable the reconstruction of the effective mean source electron spectrum F?(E) by deconvolution of the photon spectrum I(ɛ) through the bremsstrahlung cross-section Q(ɛ,E). In this paper we report on an evaluation of three distinct "inverting" reconstruction techniques and one forward fitting procedure. We synthesized a variety of hypothetical F?(E) forms, with a variety of empirical features designed to represent diagnostics of electron acceleration and transport processes, generated the corresponding I(ɛ) with realistic random noise added, and performed "blind" (i.e. without knowledge of F?[E] in advance) recoveries of F?(E) for comparison with the originally assumed forms. In most cases the inversion methods gave very good reconstructions of F?(E). The forward fitting method did well in recovering large-scale features but, somewhat inevitably, failed to recover features outwith the parametric forms of F?(E), such as dips, bumps and positive slopes. However, examination of the distribution of photon spectrum residuals over ɛ should in principle permit refinement of the parametric form used.
- Publication:
-
AGU Spring Meeting Abstracts
- Pub Date:
- May 2005
- Bibcode:
- 2005AGUSMSP21A..05E
- Keywords:
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- 7519 Flares;
- 7554 X rays;
- gamma rays;
- and neutrinos