RHESSI Images and spectra of two small flares |
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Ambretta Falchi Submitted: 2005-09-12 02:27
We studied the evolution of two small flares (GOES class C2 and C1) that developed in the same
active region with different morphological characteristics: one is
extended and the other is compact. We analyzed the accuracy and the
consistency of different algorithms implemented in RHESSI software
to reconstruct the image of the emitting sources, for energies between 3 and 12 keV. We found that all tested algorithms give consistent results
for the peak position while the other parameters can differ at most by a
factor 2. Pixon and Forward-fit generally converge to
similar results but Pixon is more reliable for reconstructing a complex source. We investigated the spectral characteristics of the two flares
during their evolution in the 3~-~25 keV energy band. We found that
a single thermal model of the photon spectrum is inadequate to fit the observations and we
needed to add either a non-thermal model or a hot thermal one.
The non-thermal and the double thermal fits are comparable.
If we assume a non-thermal model, the non-thermal energy is always higher than the thermal one.
Only during the very final decay phase a single thermal model fits fairly well the observed spectrum.
Authors: L. Maltagliati, A. Falchi, L. Teriaca
Projects: RHESSI
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Publication Status: Solar Physics (in press)
Last Modified: 2005-09-12 02:27
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