Diagnostics of non-thermal distributions in solar flare spectra observed by RESIK and RHESSI

Abstract

We focus on the non-thermal components of the electron distribution in the keV range and analyse high-energy resolution X-ray spectra detected by RESIK and RHESSI for three solar flares.In the 2-4 keV range we assume that the electron distribution can be modelled by an n-distribution. Using a method of line-intensity ratios, we analyse allowed and satellite lines of Si observed by RESIK and estimate the parameters of this n-distribution. At higher energies we explore RHESSI bremsstrahlung spectra. Adopting a forward-fitting approach and thick-target approximation, we determine the characteristics of injected electron beams. RHESSI non-thermal component associated with the electron beam is correlated well with presence of the non-thermal n-distribution obtained from the RESIK spectra. In addition, such an n-distribution occurs during radio bursts observed in the 0.61-15.4 GHz range. Furthermore, we show that the n-distribution could also explain RHESSI emission below ~5 keV. Therefore, two independent diagnostics methods indicate the flare plasma being affected by the electron beam can have a non-thermal component in the ~2-5 keV range, which is described by the n-distribution well. Finally, spectral line analysis reveals that the n-distribution does not occupy the same location as the thermal component detected by RHESSI at ~10 keV.

18 pages, 14 figures, 10 tables

References in corpus (5)

• Survey on solar X-ray flares and associated coherent radio emissions
• Kappa distribution and hard X-ray emission of solar flares
• Generalized Regularization Techniques With Constraints For The Analysis Of Solar Bremsstrahlung X-Ray Spectra
• RHESSI Observations of the Solar Flare Iron-line Feature at 6.7 keV
• Fast Spectral Fitting of Hard X-Ray Bremsstrahlung from Truncated Power-Law Electron Spectra

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• Thermal characteristics and the differential emission measure distribution during a B8.3 flare on July 04, 2009
• Call and Response: A Time-Resolved Study of Chromospheric Evaporation in a Large Solar Flare
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