Observation and Simulation of Chorus Waves Generation at the Gradients of Magnetic Holes

Abstract

International audienceThe Magnetospheric Multiscale (MMS) mission observed chorus waves at the gradients of magnetic holes on the dayside magnetosheath. The magnetic holes are nonlinear mirror structures which are anticorrelated with particle density. We used expanding box Particle-in-cell simulations and produced the mirror instability magnetic holes. We show that chorus waves are generated at the gradients of magnetic holes in our simulations which is in agreement with MMS observations. We investigate the possible mechanism for enhancing the electron temperature anisotropy at the magnetic field gradients. We analyze the electron pitch angle distributions and electron distribution functions in our simulations and compare it with MMS observations. We also measure the Poynting flux to investigate how much energy is carried away by the fields via chorus waves