Gamma‐Ray Polarimetry of Two X‐Class Solar Flares

Abstract

We have performed the first polarimetry of solar flare emission at γ-ray energies (0.2-1 MeV). These observations were performed with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) for two large flares: the GOES X4.8-class solar flare of 2002 July 23 and the X17-class flare of 2003 October 28. We have marginal polarization detections in both flares, at levels of 21% ± 9% and -11% ± 5%, respectively. These measurements significantly constrain the levels and directions of solar flare γ-ray polarization and begin to probe the underlying electron distributions.