Are Electrons in the Magnetosheath the Source of Energetic Electrons in the Magnetosphere?

Whether the electrons in the magnetosheath can be transported and energized into the magnetosphere through radial diffusion is helpful to understand the physical mechanisms in the magnetosphere. In this study, we collect more than two hundred magnetopause crossing events using GEOTAIL data, and compare the phase space density (PSD) on the two sides of the magnetopause. It is found that for most of the events, the PSDs in the magnetosheath are less than that in the magnetosphere. This indicates that through radial diffusion, electrons in the magnetosheath cannot be energized to such a high energy while transported into the magnetoshere. The electrons should be energized by other processes inside the magnetoshere.