| Issue |
A&A
Volume 405, Number 1, July I 2003
|
|
|---|---|---|
| Page(s) | 325 - 330 | |
| Section | The Sun | |
| DOI | https://doi.org/10.1051/0004-6361:20030569 | |
| Published online | 16 June 2003 | |
A regularization approach for the analysis of RHESSI X-ray spectra*
1
INFM, Unità di Ricerca di Genova, via Dodecaneso 33, 16146 Genova, Italy e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
2
INFM and Dipartimento di Matematica, Università di Genova, via Dodecaneso 35, 16146 Genova, Italy e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
3
Department of Physics, Open University, Milton Keynes MK7 6AA, UK e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
4
Department of Physics and Astronomy, The University, Glasgow G12 8QQ, UK e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
5
Department of Physics, Open University, Milton Keynes MK7 6AA, UK e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
Corresponding author: M. Piana, This email address is being protected from spambots. You need JavaScript enabled to view it.
Received:
9
January
2003
Accepted:
1
April
2003
Abstract
The Ramaty High Energy Solar Spectroscopic Imager (RHESSI) mission provides high resolution X-ray spectra emitted by collisional bremsstrahlung of electrons with the ions of the plasma. One of the aims of the mission is to infer information about the acceleration and transport mechanisms of electrons and ions in solar flares. Within the framework of an optically thin model and under the assumption of isotropic conditions in the solar plasma, the emitted photon spectrum is related to the electron flux density spectrum by an integral equation of the first kind. This problem is characterized by a notable numerical instability as a consequence of the experimental errors in the measured photon data. We address the solution of this problem by using the Tikhonov regularization algorithm. The method is applied to the case of three photon spectra registered by RHESSI detectors in the first months of the observational activity of the satellite. Furthermore a comparison of the reconstructions provided by the algorithm is performed in the case of the Kramers, Bethe-Heitler and Bethe-Heitler with the Elwert correction models for the bremsstrahlung cross-section.
Key words: Sun: flares / Sun: X-rays, gamma rays / methods: data analysis
Figures 4 and 5 and Appendix A are only available in electronic form at http://www.edpsciences.org
© ESO, 2003
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