Observations of Whistler Waves Correlated with Electron-scale Coherent Structures in the Magnetosheath Turbulent Plasma

Abstract

Abstract A new type of electron-scale coherent structure, referred to as electron vortex magnetic holes, was identified recently in the Earth’s magnetosheath turbulent plasma. These electron-scale magnetic holes are characterized by magnetic field strength depression, electron density enhancement, temperature and temperature anisotropy increase (a significant increase in perpendicular temperature and a decrease in parallel temperature), and an electron vortex formed by the trapped electrons. The strong increase of electron temperature indicates that these magnetic holes have a strong connection with the energization of electrons. Here, using high time resolution in situ measurements from the MMS mission, it is further shown that electron-scale whistler waves coexist with electron-scale magnetic holes. These whistler waves were found not propagating from remote regions, but generated locally due to electron temperature anisotropy ( T e⊥ / T e∥ ) inside the magnetic holes. This study provides new insights into the electron-scale plasma dynamics in turbulent plasmas.