Coronal Electron Distribution in Solar Flares: Drift-Kinetic Model

Abstract

Using a model of particle acceleration and transport in solar flares, we investigate the height distribution of coronal electrons by focusing on the energy-dependent pitch-angle scattering. When pitch-angle scattering is not included, the peak heights of loop-top electrons are constant, regardless of their energy, owing to the continuous acceleration and compression of the electrons via shrinkage of magnetic loops. On the other hand, under pitch-angle scattering, the electron heights are energy dependent; intermediate energy electrons are at a higher altitude, whereas lower and higher energy electrons are at lower altitudes. This implies that the intermediate energy electrons are inhibited to follow the shrinking field lines to lower altitudes because pitch-angle scattering causes efficient precipitation of these electrons into the footpoint and their subsequent loss from the loop. This result is qualitatively consistent with the position of the above-the-loop-top hard X-ray (HXR) source that is located above coronal HXR loops emitted by lower energy electrons and microwaves emitted by higher energy electrons. Quantitative agreement with observations might be achieved by considering primary acceleration before the onset of loop shrinkage and additional pitch-angle scattering via wave-particle interactions.

18 pages, 6 figures, accepted by ApJ

References in corpus (3)

• Double Coronal Hard and Soft X-ray Source Observed by RHESSI: Evidence for Magnetic Reconnection and Particle Acceleration in Solar Flares
• Comparative Analysis of Non-thermal Emissions and Study of Electron Transport in a Solar Flare
• Drift-Kinetic Modeling of Particle Acceleration and Transport in Solar Flares

Cited by in corpus (10)

• Electron Power-Law Spectra in Solar and Space Plasmas
• Non-Equilibrium Processes in the Solar Corona, Transition Region, Flares, and Solar Wind \textit{(Invited Review)}
• Determination of Stochastic Acceleration Model Characteristics in Solar Flares
• Impulsive Phase Coronal Hard X-ray Sources in an X3.9 Class Solar Flare
• Numerical Modeling of Energetic Electron Acceleration, Transport, and Emission in Solar Flares: Connecting Loop-top and Footpoint Hard X-Ray Sources
• Particle Acceleration in Collapsing Magnetic Traps with a Braking Plasma Jet
• Loss cone evolution and particle escape in collapsing magnetic trap models in solar flares
• Particle energisation in a collapsing magnetic trap model: the relativistic regime
• Particle acceleration with anomalous pitch angle scattering in 3D separator reconnection
• Stochastic Electron Acceleration by Temperature Anisotropy Instabilities Under Solar Flare Plasma Conditions