Multi-Wavelength Analysis of High-Energy Electrons in Solar Flares: A Case Study of the August 20, 2002 Flare |
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| Authors: | Jana Ka?parová Marian KarlickÝ Eduard P Kontar Richard A Schwartz Brian R Dennis |
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| Institution: | (1) Astronomical Institute, Academy of Sciences of the Czech Republic, 251 65 Ondřejov, Czech Republic;(2) Department of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, U.K.;(3) Science Systems & Applications Inc. at NASA Goddard Space Flight Center, Greenbelt, MD, 20771, U.S.A.;(4) NASA Goddard Space Flight Center, Greenbelt, MD, 20771, U.S.A. |
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| Abstract: | A multi-wavelength spatial and temporal analysis of solar high-energy electrons is conducted using the August 20, 2002 flare
of an unusually flat (γ1 = 1.8) hard X-ray spectrum. The flare is studied using RHESSI, Hα, radio, TRACE, and MDI observations with advanced methods
and techniques never previously applied in the solar flare context. A new method to account for X-ray Compton backscattering
in the photosphere (photospheric albedo) has been used to deduce the primary X-ray flare spectra. The mean electron flux distribution
has been analysed using both forward fitting and model-independent inversion methods of spectral analysis. We show that the
contribution of the photospheric albedo to the photon spectrum modifies the calculated mean electron flux distribution, mainly
at energies below ∼100 keV. The positions of the Hα emission and hard X-ray sources with respect to the current-free extrapolation
of the MDI photospheric magnetic field and the characteristics of the radio emission provide evidence of the closed geometry
of the magnetic field structure and the flare process in low altitude magnetic loops. In agreement with the predictions of
some solar flare models, the hard X-ray sources are located on the external edges of the Hα emission and show chromospheric
plasma heated by the non-thermal electrons. The fast changes of Hα intensities are located not only inside the hard X-ray
sources, as expected if they are the signatures of the chromospheric response to the electron bombardment, but also away from
them. |
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