http://www.cnr.it/ontology/cnr/individuo/prodotto/ID43

Evaluation of algorithms for reconstructing electron spectra from their bremsstrahlung hard X-ray spectra (Articolo in rivista)

Type

Articolo in rivista (Classe)
Prodotto della ricerca (Classe)

Label

Evaluation of algorithms for reconstructing electron spectra from their bremsstrahlung 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

10.1086/501497 (literal)

Alternative label

Brown, JC; Emslie, AG; Holman, GD; Johns-Krull, CM; Kontar, EP; Lin, RP; Massone, AM; Piana, M (2006)
Evaluation of algorithms for reconstructing electron spectra from their bremsstrahlung hard X-ray spectra
in The Astrophysical journal; University of Chicago Press, Chicago (Stati Uniti d'America)
(literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori

Brown, JC; Emslie, AG; Holman, GD; Johns-Krull, CM; Kontar, EP; Lin, RP; Massone, AM; Piana, M (literal)

Pagina inizio

523 (literal)

Pagina fine

531 (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#url

http://iopscience.iop.org/0004-637X/643/1/523/ (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume

643 (literal)

Rivista

?The ?Astrophysical journal (Rivista)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#pagineTotali

9 (literal)

Note

ISI Web of Science (WOS) (literal)
Scopu (literal)
Google Scholar (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni

Univ Glasgow, Dept Phys & Astron, Glasgow G12 8QQ, Lanark, Scotland; Univ Alabama, Dept Phys, Huntsville, AL 35899 USA; Oklahoma State Univ, Dept Phys, Stillwater, OK 74078 USA; NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA; Rice Univ, Dept Phys & Astron, Houston, TX 77005 USA; Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA; CNR, INFM, LAMIA, I-16146 Genoa, Italy; Univ Genoa, Dipartimento Matemat, I-16146 Genoa, Italy; Univ Verona, Dipartimento Informat, I-37134 Verona, Italy (literal)

Titolo

Evaluation of algorithms for reconstructing electron spectra from their bremsstrahlung hard X-ray spectra (literal)

Abstract

The Ramaty High Energy Solar Spectroscopic Imager (RHESSI) has yielded solar flare hard X-ray spectra with unprecedented resolution, enabling reconstruction of mean source electron energy spectra F(E) by deconvolution of photon energy spectra I(epsilon). While various algorithms have been proposed, the strengths and weaknesses of each have yet to be explored in a systematic fashion. For real data F(E) is unknown, so these various algorithms must instead be tested on simulated data for which the 'true'' F(E) is known. Accordingly, we devised several forms of F(E) with 'interesting'' features, generated the corresponding (noise-added) I (epsilon), and recovered F(E) using a variety of algorithms, including zero- and first-order Tikhonov regularizations, triangular matrix row elimination, and forward fitting using a parametric form consisting of a double power law with low/high cutoffs plus an isothermal component. All inversion methods reconstructed the general magnitude and form of F(E) well, suffering only from (1) blurring of sharp features and (2) poor recovery at low electron energies E in cases in which F'(E) was positive and large. Addition of a steep thermal component at low E did not prevent recovery of features at higher values of E. Forward fitting did recover large-scale forms and features well but, inevitably, failed to recover local features not expressible within the parametric used. This confirms that inversions are the most dependable way to discover such features. However, examination of the pattern of I(epsilon) residuals can suggest feature locations and so help refine the parametric form used. Since quite smooth F(E) forms do reproduce the observed I(epsilon) form with relatively small residuals, it appears that sharp features may be uncommon in actual flares. (literal)

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