Volume 533, September 2011
|Number of page(s)||16|
|Published online||30 August 2011|
Diagnostics of non-thermal distributions in solar flare spectra observed by RESIK and RHESSI⋆
Astronomical Institute of the Academy of Sciences of the Czech Republic, v. v. i., Fričova 298, 251 65 Ondřejov, Czech Republic
e-mail: firstname.lastname@example.org; email@example.com; firstname.lastname@example.org; email@example.com
2 Department of Astronomy, Physics of the Earth and Meteorology, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynská dolina, 842 48 Bratislava, Slovakia
3 Space Research Centre, Polish Academy of Sciences, 51-622, Kopernika 11, Wrocław, Poland
e-mail: firstname.lastname@example.org; email@example.com
Received: 17 February 2011
Accepted: 7 July 2011
Context. During solar flares an enormous amount of energy is released, and the charged particles, like electrons, are accelerated. These non-thermal electrons interact with the plasma in various parts of solar flares, where the distribution function of electrons can therefore be non-Maxwellian.
Aims. 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.
Methods. 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.
Results. 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.
Key words: Sun: flares / Sun: X-rays, gamma rays / Sun: radio radiation / radiation mechanisms: non-thermal / methods: data analysis
Appendix A is available in electronic form at http://www.aanda.org
© ESO, 2011
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.