Kappa distribution and hard X-ray emission of solar flares
Abstract
Aims: We investigate whether the so-called kappa distribution, often used to fit electron distributions detected in situ in the solar wind, can describe electrons producing the hard X-ray emission in solar flares.
Methods: Using Ramaty High Energy Solar Spectroscopic imager (RHESSI) flare data we fit spatially- and feature-integrated spectra, assuming a kappa distribution for the mean electron flux spectrum.
Results: We show that a single kappa distribution generally cannot describe spatially integrated X-ray emission composed of both footpoint and coronal sources. In contrast, the kappa distribution is consistent with mean electron spectra producing hard X-ray emission in some coronal sources.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- April 2009
- DOI:
- 10.1051/0004-6361/200911898
- arXiv:
- arXiv:0902.3574
- Bibcode:
- 2009A&A...497L..13K
- Keywords:
-
- Sun: flares;
- Sun: X-rays;
- gamma rays;
- methods: data analysis;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 4 pages, 4 figures, changed content, accepted to A&