Wave-particle Interactions due to the Whistler Wave along the Separatrix in Asymmetric Magnetic Reconnection

Magnetic reconnection is one of the important energy conversion processes in space physics and laboratory plasma physics. Using 2-D particle-in-cell (PIC) simulations of asymmetric guide field reconnection in the Earth's dayside magnetopause, we reveal effects of whistler waves along the separatrix on the magnetospheric side. In Choi et al. (2022), we demonstrated that whistler waves are generated near/inside the electron diffusion region (EDR) by two mechanisms: the electron cyclotron resonance, and the Landau resonance, and the waves propagate away from the X line along the separatrix in the side of the stronger reconnection outflow. In this study, we investigate the energy conversion between the whistler waves and electrons, focusing on the region outside the EDR. The whistler wave amplitude increases as the wave propagates along the separatrix, and we discuss the nonlinear regime of the wave based on the Poynting theorem. We show that the parallel and perpendicular electron temperatures are modulated along the separatrix, and the modulation matches wave patterns of the whistler wave along the separatrix. We investigate wave-particle interactions due to the whistler waves by performing particle tracing in the PIC simulation. Some electrons show that their energies are increasing with time during the motion along the separatrix, and at the same time the energies show modulation with a similar frequency as the whistler wave, which indicates a signature of wave-particle interactions. We discuss particle motion, energy increase due to each component of electric fields, and the evolution of electron distribution functions in the region of strong whistler waves.