Regularized reconstruction of the differential emission measure from solar flare hard X-ray spectra (Articolo in rivista)

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Label
  • Regularized reconstruction of the differential emission measure from solar flare hard X-ray spectra (Articolo in rivista) (literal)
Anno
  • 2006-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1007/s11207-006-0029-1 (literal)
Alternative label
  • M Prato; M Piana; JC Brown; AG Emslie; EP Kontar; AM Massone (2006)
    Regularized reconstruction of the differential emission measure from solar flare hard X-ray spectra
    in Solar physics; SPRINGER, DORDRECHT (Paesi Bassi)
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • M Prato; M Piana; JC Brown; AG Emslie; EP Kontar; AM Massone (literal)
Pagina inizio
  • 61 (literal)
Pagina fine
  • 83 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#url
  • http://www.springerlink.com/content/77838h663w587361/ (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 237 (literal)
Rivista
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  • Google Scholar (literal)
  • Scopu (literal)
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Univ Genoa, Dipartimento Matemat, I-16146 Genoa, Italy; Univ Verona, Dipartimento Informat, I-37134 Verona, Italy; Univ Glasgow, Dept Phys & Astron, Glasgow G12 8QQ, Lanark, Scotland; Oklahoma State Univ, Dept Phys, Stillwater, OK 74078 USA; CNR, INFM LAMIA, I-16146 Genoa, Italy (literal)
Titolo
  • Regularized reconstruction of the differential emission measure from solar flare hard X-ray spectra (literal)
Abstract
  • We address the problem of how to test whether an observed solar hard X-ray bremsstrahlung spectrum ( I(epsilon)) is consistent with a purely thermal ( locally Maxwellian) distribution of source electrons, and, if so, how to reconstruct the corresponding differential emission measure (xi(T)). Unlike previous analysis based on the Kramers and Bethe-Heitler approximations to the bremsstrahlung cross-section, here we use an exact (solid-angle-averaged) cross-section. We show that the problem of determining xi(T) from measurements of I (epsilon) invOlves two successive inverse problems: the first, to recover the mean source-electron flux spectrum ((F) over bar (E)) from I (epsilon) and the second, to recover. ( T) from (F) over bar (E). We discuss the highly pathological numerical properties of this second problem within the framework of the regularization theory for linear inverse problems. In particular, we show that an iterative scheme with a positivity constraint is effective in recovering delta-like forms of xi(T) while first-order Tikhonov regularization with boundary conditions works well in the case of power-law-like forms. Therefore, we introduce a restoration approach whereby the low-energy part of (F) over bar (E), dominated by the thermal component, is inverted by using the iterative algorithm with positivity, while the high-energy part, dominated by the power-law component, is inverted by using first-order regularization. This approach is first tested by using simulated (F) over bar (E) derived from a priori known forms of xi(T) and then applied to hard X-ray spectral data from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). (literal)
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