In Situ Detection of Kinetic-Size Magnetic Holes in the Martian Magnetosheath

Depression in magnetic field strength with a scale below one proton gyroradius is referred to as kinetic-size magnetic hole (KSMH). KSMHs are frequently observed near terrestrial space environments and are thought to play an important role in electron energization and energy dissipation in space plasmas. Recently, KSMHs have been evidenced in the Venusian magnetosheath. However, observations of KSMHs in other planetary environments are still lacking. In this study, we present the in situ detection of KSMHs in Martian magnetosheath using Mars Atmosphere and Volatile EvolutioN (MAVEN) for the first time. The distribution of KSMHs is asymmetry in the southern northern hemisphere and no obvious asymmetry in the dawn dusk hemisphere. The observed KSMHs are accompanied by increases in the electron fluxes in the perpendicular direction, indicating the cues of trapped electrons and the formation of electron vortices inside KSMHs. These features are similar to the observations in the terrestrail magtosheath and magnetotail plasma sheet and the Venusian magnetosheath. This implies that KSMHs are a universal magnetic structure in space.
Comment: 16 pages, 4 figures, accepted by ApJ