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The sub-arcsecond hard X-ray structure of loop footpoints in a solar flare View all abstracts by submitter

Eduard Kontar   Submitted: 2010-05-22 10:41

The newly developed X-ray visibility forward fitting technique is applied to Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) data of a limb flare to investigate the energy and height dependence on sizes, shapes, and position of hard X-ray chromospheric footpoint sources. This provides information about the electron transport and chromospheric density structure. The spatial distribution of two footpoint X-ray sources is analyzed using PIXON, Maximum Entropy Method, CLEAN and visibility forward fit algorithms at nonthermal energies from sim 20 to sim 200 keV. We report, for the first time, the vertical extents and widths of hard X-ray chromospheric sources measured as a function of energy for a limb event. Our observations suggest that both the vertical and horizontal sizes of footpoints are decreasing with energy. Higher energy emission originates progressively deeper in the chromosphere consistent with downward flare accelerated streaming electrons. The ellipticity of the footpoints grows with energy from sim 0.5 at sim 20 keV to sim 0.9 at sim 150 keV. The positions of X-ray emission are in agreement with an exponential density profile of scale height sim 150 km. The characteristic size of the hard X-ray footpoint source along the limb is decreasing with energy suggesting a converging magnetic field in the footpoint. The vertical sizes of X-ray sources are inconsistent with simple collisional transport in a single density scale height but can be explained using a multi-threaded density structure in the chromosphere.

Authors: Kontar, E. P., Hannah, I. G., Jeffrey, N. L. S., Battaglia, M.
Projects: RHESSI

Publication Status: Submitted to ApJ
Last Modified: 2010-05-23 14:14
Go to main E-Print page  Observational Evidence of Back-reaction on the Solar Surface Associated with Coronal Magnetic Restructuring in Solar Eruptions  Accelerating waves in polar coronal holes as seen by EIS and SUMER  Edit Entry  Download Preprint  Submitter's Homepage Delete Entry 

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