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Title: Electron acceleration at a coronal shock propagating through a large-scale streamer-like magnetic field

With a test-particle simulation, we investigate the effect of large-scale coronal magnetic fields on electron acceleration at an outward-propagating coronal shock with a circular front. The coronal field is approximated by an analytical solution with a streamer-like magnetic field featured by partially open magnetic field and a current sheet at the equator atop the closed region. We show that the large-scale shock-field configuration, especially the relative curvature of the shock and the magnetic field line across which the shock is sweeping, plays an important role in the efficiency of electron acceleration. At low shock altitudes, when the shock curvature is larger than that of magnetic field lines, the electrons are mainly accelerated at the shock flanks; at higher altitudes, when the shock curvature is smaller, the electrons are mainly accelerated at the shock nose around the top of closed field lines. The above process reveals the shift of efficient electron acceleration region along the shock front during its propagation. We also found that in general the electron acceleration at the shock flank is not so efficient as that at the top of closed field since at the top a collapsing magnetic trap can be formed. In addition, we find thatmore » the energy spectra of electrons is power-law like, first hardening then softening with the spectral index varying in a range of -3 to -6. In conclusion, physical interpretations of the results and implications on the study of solar radio bursts are discussed.« less
Authors:
 [1] ; ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [1] ;  [1] ; ORCiD logo [3]
  1. Shandong Univ., Jinan (China). Shandong Provincial Key Lab. of Optical Astronomy and Solar-Terrestrial Environment, and Inst. of Space Sciences
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division
  3. Univ. of Alabama in Huntsville, Huntsville, AL (United States). Dept. of Space Science and CSPAR
Publication Date:
Report Number(s):
LA-UR-16-20148
Journal ID: ISSN 1538-4357
Grant/Contract Number:
AC52-06NA25396; ATM-0847719; AGS1135432; ZR2014DQ001; ZR2013DQ004; NSBRSF 2012CB825601; NNSFC 11503014; 41274175; 41331068; U1431103
Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 821; Journal Issue: 1; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE; Shandong Universit; Natural Science Foundation of Shandong Province
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; 79 ASTRONOMY AND ASTROPHYSICS; Astronomy and Astrophysics; acceleration of particles; shock waves; Sun: coronal mass ejections; (CMEs); Sun: radio radiation
OSTI Identifier:
1338739