Direct Evidence of a Highest Wave-Driven Energetic Electron Flux at the Earth's Magnetopause

Abstract

Spacecraft observations of high-energy electron flux enhancement up to 125 keV at Earth's magnetopause are typically linked to the magnetic reconnection. Here, we report the first ever observation of prolonged electron flux enhancement reaching very high energy up to 650 keV at magnetopause near the subsolar point, notably without reconnection signatures. The observation reveals that the high-energy electron flux enhancement near the magnetopause is associated with the simultaneous occurrence of electron cyclotron wave harmonics, whistler waves, and Langmuir waves. Theoretical modeling confirms the wave generation by electron temperature anisotropy and the electron loss cone distribution. This direct, in-situ observation of high-energy electron flux linked to cascaded wave-particle interactions will help us advance our understanding about the tiniest electron-scale intricacies affecting near-Earth space weather.