In-situ evidence of electron energization in the electron diffusion region of magnetotail reconnection

TL;DR

This study provides in-situ evidence that the electron diffusion region in Earth's magnetotail actively contributes to electron energization during magnetic reconnection, with observed heating and demagnetization effects.

Contribution

First direct observational evidence showing the electron diffusion region's role in electron energization during magnetic reconnection.

Findings

Significant electron heating and demagnetization observed in the EDR.

Energization occurs both upstream and downstream of the EDR.

Total electron energy increase exceeds an order of magnitude.

Abstract

Magnetic reconnection is an explosive energy-release process in laboratory, space and astrophysical plasmas. While magnetic fields can `break' and `reconnect' in a very small region called the electron diffusion region (EDR), there have been conflicting theories as to whether this region can be a place of rapid energization of plasmas. Here we report a fortuitous encounter of the EDR by THEMIS in the Earth's magnetotail where significant heating and demagnetization of electrons were observed. Additional energization was observed on both sides (immediate upstream and downstream) of the EDR, leading to a total of more than an order of magnitude energization across this region. The results demonstrate that, despite its minuscule size, the EDR does indeed contribute to the overall process of electron energization via magnetic reconnection.