Magnetic reconnection is a fundamental and universal process, which transfers energy stored in the magnetic field to kinetic and thermal energies of charged particles. NASA’s Magnetospheric Multiscale (MMS) mission was designed to investigate the electron diffusion region (EDR), which is the core region of the reconnection where the magnetic field lines break and reconnect. Various types of plasma waves have been reported in and near EDRs. Recent studies reveal that only two types of high-frequency electrostatic waves (upper-hybrid waves and electron Bernstein waves) are driven by the crescent-shaped agyrotropic electron distribution functions in the EDRs. The kinetic interaction between the electrons and the large-amplitude electrostatic waves can thermalize electrons and change the electron pressure tensor. Therefore, those electrostatic waves may modify the reconnection electric field and have feedback on the reconnection process.

electrostatic waves,electron crescents,MMS,magnetic reconnection