Study of the Electron-Scale Magnetic Peaks in the Magnetotail Current Sheet Observed by the Magnetospheric Multiscale Mission

Electron-scale magnetic holes have been revealed to widely exist in many plasma environments in the last decade, playing an important role in transporting particles and dissipating energies. Recently, electron-scale magnetic peaks (ESMPs) have also been reported to exist in the terrestrial magnetosheath and the solar wind at 1 AU. Here, we report the existence of ESMPs in the terrestrial magnetotail current sheet for the first time based on observations of the Magnetospheric Multiscale (MMS) mission. We find a clear bipolar signature in the electron velocity inside one ESMP, suggesting the existence of an electron vortex inside it. The current in the ESMP is mainly contributed by electrons. We also find that they prefer to occur near the neutral sheet with a northward component of the magnetic field, suggesting that they prefer to occur during the dipolarization process. Our observation results suggest that both ion and electron mirror instabilities are not the generation mechanism of these ESMPs. Their role and generation mechanism in the magnetotail current sheet are unclear and need further investigation.