[P-EM14] Frontiers in solar physics

[PEM14-P02] Quantitative study of pitch angle distribution through microwave fast propagation in a solar flare observed with Nobeyama Radioheliograph

*Keitaro Matsumoto¹, Satoshi Masuda¹, Kazumasa Iwai¹, Takafumi Kaneko², Takashi Minoshima³ (1.Institute for Space-Earth Environmental Research, Nagoya University, 2.LMSAL, HAO/NCAR, 3.Center for Mathematical Science and Advanced Technology, Japan Agency for Marine-Earth Science and Technology)

Keywords:solar flare, microwave radiation

The mechanism of particle acceleration during solar flares still remains controversial in solar physics. The pitch angle distribution of the accelerated electrons represents an important element in understanding this mechanism. Electrons that are accelerated to nearly relativistic speeds emit non-thermal microwaves. By using the Nobeyama Radioheliograph (NoRH), [Yokoyama+2002] estimated the pitch angle of accelerated electrons by analyzing the propagation velocity of non-thermal microwave sources. We found another flare event (an M-class flare on October 22, 2014) that showed similar observational features and evaluated the pitch angle of the accelerated electrons through multi-wavelength observations with NoRH, SDO, and Fermi, and computer simulations with the coronal magnetic field obtained from the NLFFF model. Finally, we concluded that electron injection took place toward one footpoint of the loop and also obtained results indicating a bouncing motion of the injected electrons along the magnetic loop (submitted to ApJL).

This presentation will undertake a theoretical examination of the position and pitch angle distribution of injected electrons within the loop. By solving the Fokker-Plank equation, we will determine the phase space density with pitch angle and energy as independent variables in an 1D coordinate system along the magnetic loop, as determined by the NLFFF model. This will allow us to investigate the bouncing motion of electrons along the loop. The time-varying 17 GHz microwave emission along the loop will be determined through the solution of the Fokker-Plank equation. Our results indicate that electron injection occurred in the direction of the footpoint on one side. We will also employ this method to conduct a comprehensive survey of the parameters affecting the injection position and pitch angle distribution of accelerated electrons, and compare the results to observations, with a focus on discussing the injection of accelerated electrons in this event.