Letter to the Editor
Kappa distribution and hard X-ray emission of solar flares
Astronomický ústav AV ČR, v.v.i., Fričova 298, 251 65 Ondřejov, Czech Republic e-mail: email@example.com
Accepted: 5 March 2009
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.
Key words: Sun: flares / Sun: X-rays / gamma rays / methods: data analysis
© ESO, 2009