Imaging spectroscopy in electron space Marco Prato Pure and Applied Mathematics Department University of Modena and Reggio Emilia, Italy CNR – INFM LAMIA, Genova, Italy IX RHESSI Workshop Genova, September 3 rd

Previously… Back to spectroscopy… Implementation of a software for the reconstruction of the mean electron flux spectrum in a flare given the X-ray spectrum observed by RHESSI and a cross section X-ray spectrum Mean electron flux spectrum Bremsstrahlung cross section Massone A.M., Piana M. and Prato M. 2008, “Regularized solution of the solar bremsstrahlung inverse problem: model dependence and implementation issues”, Inverse Problems in Science and Engineering 16,

The idea RHESSI – NESSI IV, Paris, 3-4 April 2006 The spectroscopy software can be used here! X-rays Electrons

Reformulation of the method Temporal modulation data Count visibilitiesCount images Fourier Transform Electron imagesElectron visibilities Regularized Inversion Fourier Transform Piana M., Massone A.M., Hurford G.J., Prato M., Emslie A.G., Kontar E.P. and Schwartz R.A. 2007, “Electron flux spectral imaging of solar flares through regularized analysis of hard X-ray source visibilities”, The Astrophysical Journal 665, N.B.: The electron visibilities extend over a greater energy range than the count visibilities!

New test RHESSI – NESSI V, Berkeley, 6-8 November 2006 Back-projection

New test improved 7 th RHESSI Workshop, Santa Cruz, June 2007 MEM-NJIT

Local flux 7 th RHESSI Workshop, Santa Cruz, June th RHESSI Workshop, Potsdam, 2-6 September 2008

Simulated data 8 th RHESSI Workshop, Potsdam, 2-6 September 2008 Prato M., Piana M., Emslie A.G., Hurford G.H., Kontar E.P. and Massone A.M., “A regularized visibility-based approach to astronomical imaging spectroscopy”, SIAM Journal on Imaging Sciences, in press

Today New method to get electron images of a flare Software close to be ready Test on simulated data ok Test on (few) real data ok Need to understand why and how to use it Push people to use it

What we can do from electron maps get the variation of the electron spectrum in both space and time at a more elementary level, "locate" (using centroids) where the electrons are (and the structure of the region in which they propagate), rather than where the X-rays are (which is of diagnostic, but not physical, interest) locate the region of steepest spectrum, which is most likely the acceleration region itself examine the variation of electron spectrum with position to understand the physical processes associated with electron propagation in the source (Emslie, Barrett & Brown 2001) examine source asymmetries in order to better understand the flare geometry, and compare results with other observations (magnetograms, UV images, optical images)