DECONVOLUTION OF DIRECTLY PRECIPITATING AND TRAP-PRECIPITATING ELECTRONS IN SOLAR FLARE HARD X-RAYS. III. YOHKOH HARD X-RAY TELESCOPE DATA ANALYSIS

摘要

We analyze the footpoint separation d and flux asymmetry A of magnetically conjugate double foot- point sources in hard X-ray images from the Yohkoh Hard X-Ray Telescope (HXT). The data set of 54 solar flares includes all events simultaneously observed with the Compton Gamma Ray Observatory (CGRO) in high time resolution mode. From the CGRO data we deconvolved the direct-precipitation and trap-precipitation components previously (in Paper II). Using the combined measurements from CGRO and HXT, we develop an asymmetric trap model that allows us to quantify the relative fractions of four different electron components, i.e., the ratios of direct-precipitating (q_p1, q_p2) and trap- precipitating electrons (q_T1, q_T2) at both magnetically conjugate footpoints. We find mean ratios of q_p1 = 0.14 ± 0.06, q_p2 = 0.26 ± 0.10, and q_T = q_T1 + q_T2 = 0.60 ± 0.13. We assume an isotropic pitch- angle distribution at the acceleration site and double-sided trap precipitation (q_T2/q_T1 = q_p2/q_P1) to determine the conjugate loss-cone angles ( α_1 = 42°±11°and α_2= 52°± 10°) and magnetic mirror ratios at both footpoints (R_1 = 1.6, . . . , 4.0 and R_2=1.3,...,2.5). From the relative displacement of footpoint sources we also measure altitude differences of hard X-ray emission at different energies, Which are found to decrease systematically with higher energies, with a statistical height difference of h_Lo -h_M1=980 ± 250 km and h_M1 - h_M2 = 310 ± 300 km between the three lower HXT energy channels (Lo, M1, M2).