Relationship between non-thermal electron energy spectra and GOES classes

¹ Astronomical Institute, University of Wrocław, 51-622 Wrocław, ul. Kopernika 11, Poland e-mail: [falewicz;rudawy]@astro.uni.wroc.pl
² Space Research Centre, Polish Academy of Sciences, 51-622 Wrocław, ul. Kopernika 11, Poland e-mail: ms@cbk.pan.wroc.pl

Received: 17 November 2008
Accepted: 31 March 2009

Abstract

Aims. We investigate influence of variations in the energy spectrum of non-thermal electrons on the resulting GOES classes of solar flares.

Methods. Twelve observed flares with various soft-to-hard X-ray emission ratios were modeled using different non-thermal electron energy distributions. Initial values of the flare physical parameters including geometrical properties were estimated using observations.

Results. We found that, for a fixed total energy of non-thermal electrons in a flare, the resulting GOES class of the flare can change significantly by varying the spectral index and low energy cut-off of the non-thermal electron distribution. Thus, the GOES class of a flare depends not only on the total non-thermal electrons energy but also on the electron beam parameters. For example, we were able to convert a M2.7 class solar flare into a merely C1.4 class one and a B8.1 class event into a C2.6 class flare. The results of our work also suggest that the level of correlation between the cumulative time integral of HXR and SXR fluxes can depend on the considered HXR energy range.