Electron heating along the separatrix due to whistler waves in asymmetric magnetic reconnection

Magnetic reconnection is one of the important energy conversion processes in collisionless plasma. Using 2-D particle-in-cell (PIC) simulations of asymmetric guide field reconnection (30% of the reconnecting magnetic field), we investigate wave-particle interactions in the magnetosphere side of the separatrix, outside the electron diffusion region. 2-D plots of the energy conversion term in the Poynting equation show that there is a strong energy conversion between waves and particles along the separatrix. Large-amplitude whistler waves are generated along the separatrix by two mechanisms: one is the electron cyclotron resonance due to an anisotropic high-speed electron beam, and the other is the Landau resonance due to a hot slow electron beam [Choi et al. 2022]. 2-D plots of parallel and perpendicular electron temperatures show modulation along the separatrix, which matches the wave pattern of the whistler wave. Performing particle tracing in the simulation, we investigate how electrons are energized by the whistler wave along the separatrix. Some electrons show energy increase with modulation whose frequency is similar to the wave frequency, suggesting that electrons are energized by the wave-particle interaction with the whistler wave.