Generalized regularization techniques with constraints for the analysis of solar bremsstrahlung x-ray spectra

Kontar, E.P., Piana, M., Massone, A.M., Emslie, A.G. and Brown, J.C. (2004) Generalized regularization techniques with constraints for the analysis of solar bremsstrahlung x-ray spectra. Solar Physics, 225(2), pp. 293-309. (doi:10.1007/s11207-004-4140-x)

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Abstract

Hard X-ray spectra in solar flares provide knowledge of the electron spectrum that results from acceleration and propagation in the solar atmosphere. However, the inference of the electron spectra from solar X-ray spectra is an ill-posed inverse problem. Here, we develop and apply an enhanced regularization algorithm for this process making use of physical constraints on the form of the electron spectrum. The algorithm incorporates various features not heretofore employed in the solar flare context: Generalized Singular Value Decomposition (GSVD) to deal with different orders of constraints; rectangular form of the cross-section matrix to extend the solution energy range; regularization with various forms of the smoothing operator; and "preconditioning" of the problem. We show by simulations that this technique yields electron spectra with considerably more information and higher quality than previous algorithms.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Kontar, Professor Eduard and Brown, Professor John and Piana, Professor Michele and Emslie, Professor Gordon and Massone, Dr Anna
Authors: Kontar, E.P., Piana, M., Massone, A.M., Emslie, A.G., and Brown, J.C.
Subjects:Q Science > QB Astronomy
Q Science > QC Physics
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Solar Physics
ISSN:1573-093X
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