Stereoscopic Electron Spectroscopy of Solar Hard X-Ray Flares with a Single Spacecraft
Abstract
Hard X-ray (HXR) spectroscopy is the most direct method of diagnosing energetic electrons in solar flares. Here we present a technique that allows us to use a single HXR spectrum to determine an effectively stereoscopic electron energy distribution. Considering the Sun's surface to act as a ``Compton mirror'' allows us to look at emitting electrons also from behind the source, providing vital information on downward-propagating particles. Using this technique we determine simultaneously the electron spectra of downward- and upward-directed electrons for two solar flares observed by the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The results reveal surprisingly near-isotropic electron distributions, which contrast strongly with the expectations from the standard model that invokes strong downward beaming, including a collisional thick-target model.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 2006
- DOI:
- 10.1086/510586
- arXiv:
- arXiv:astro-ph/0611170
- Bibcode:
- 2006ApJ...653L.149K
- Keywords:
-
- Sun: Flares;
- Sun: Particle Emission;
- Sun: X-Rays;
- Gamma Rays;
- Astrophysics
- E-Print:
- 7 pages, 3 figures, accepted to Astrophysical Journal Letters