Deconvolution of directly precipitating and trap-precipitating electrons in solar flare hard x-rays. III.Yohkoh hard x-ray telescope data analysis

Aschwanden, M.J., Fletcher, L. , Sakao, T., Kosugi, T. and Hudson, H. (1999) Deconvolution of directly precipitating and trap-precipitating electrons in solar flare hard x-rays. III.Yohkoh hard x-ray telescope data analysis. Astrophysical Journal, 517(2), pp. 977-989. (doi: 10.1086/307230)

Abstract

We analyze the footpoint separation d and flux asymmetry A of magnetically conjugate double footpoint 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 (alpha_1=42^deg+/-11^deg and alpha_2=52^deg+/-10^deg) and magnetic mirror ratiosat 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)

• Item Type: Articles
• Keywords: ACCELERATION OF PARTICLES, RADIATION MECHANISMS: NONTHERMAL, SUN: CORONA, SUN: FLARES, SUN: X-RAYS, GAMMA RAYS
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Fletcher, Professor Lyndsay and Hudson, Dr Hugh
• Authors: Aschwanden, M.J., Fletcher, L., Sakao, T., Kosugi, T., and Hudson, H.
• Subjects: Q Science > QB Astronomy; Q Science > QC Physics
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Research Group: Astronomy and Astrophysics
• Journal Name: Astrophysical Journal
• Publisher: American Astronomical Society
• ISSN: 0004-637X
• ISSN (Online): 1538-4357
• Copyright Holders: Copyright © 1999 American Astronomical Society
• First Published: First published in Astrophysical Journal 517(2):977-989
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher