Magnetic reconnection is a fundamental process known to play a crucial role in electron acceleration and heating, however, the mechanism of electron energization during reconnection is still not fully understood. This study introduces a novel electron acceleration mechanism in which electrons can be accelerated by secondary reconnection in the separatrix region. The secondary reconnection occurs in a thin current sheet resulted from the shear of the out-of-plane Hall magnetic fields of the primary magnetopause reconnection. It results in intense electron energy fluxes towards the primary X-line. This result will likely be an important piece in the puzzle of particle acceleration by reconnection.

In this paper, dayside magnetopause energy transport (energy transport across the separatrix surface to the magnetopause boundary layer and energy transport inside the magnetopause boundary layer) and its dependence on the magnetopause dynamic evolution under purely southward interplanetary magnetic field (IMF) conditions are studied via a 3-D global hybrid simulation. By investigating the energy transport across the separatrix surface, current layer surface, and magnetopause surface, we find that the energy transport from the magnetosheath to the magnetopause boundary layer is mainly in the form of electromagnetic energy, while the energy transport directly across the magnetopause surface to the magnetosphere is mainly in the form of plasma energy. The energy transport across the magnetopause surface exhibits temporal variability, driven by the dynamic evolution of reconnection and flux rope. During the development of multiple X-lines reconnection and flux rope, a substantial portion of solar wind energy does not directly penetrate the dayside magnetopause to the magnetosphere. Instead, it is transported with the reconnection outflow and flux rope from low latitude to high latitude, and with the drifting flow from the subsolar region to the tail magnetopause within the magnetopause current layer. These results significantly improve our understanding of solar wind-magnetosphere coupling at the dayside magnetopause.

A document by Liangjin Song. Click on the document to view its contents.