PIC simulation study of microinstability from the electron beam and the crescent distribution near the electron diffusion region

Wave activity plays an important role in magnetic reconnection processes. Waves are considered one of several possible mechanisms triggering reconnection as well as providing energy dissipation mechanism during reconnection. Previous observations showed that various electron scale waves are generated in the reconnection site. Recent simulation studies and Magnetospheric Multiscale (MMS) satellite observations have reported that agyrotropic distributions such as electron beams and crescent distributions form near/in the electron diffusion region and they are closely related to the wave activities. In this presentation, we investigate microinstabilities of the electron beam and crescent distribution using two-dimensional particle-in-cell (PIC) simulations. Our simulation results show that whistler-mode waves and Langmuir waves are generated from the beam and crescent distribution. The wave vector direction of maximum growth rate highly depends on the angle (θ) between the axis of agyrotropic distribution and the background magnetic field (B0). We compared simulation cases by changing simulation conditions such as θ and the density of agyrotropic electrons to provide the detailed context for the observations. This enables us to demonstrate how the electron microinstabilities regulate the reconnection processes and contribute to the energy dissipation occurring in the vicinity of reconnection sites.