Two-dimensional particle-in-cell simulation of magnetic reconnection in the downstream of a quasi-perpendicular shock

TL;DR

This study uses 2D particle-in-cell simulations to explore magnetic reconnection downstream of a quasi-perpendicular shock, revealing complex current sheet dynamics and electron-scale reconnection processes.

Contribution

It provides new insights into the formation and fragmentation of current sheets and electron-scale reconnection in shock downstream regions.

Findings

Formation of filamentary current sheets due to shock reformation.

Electron-scale magnetic reconnection occurs in downstream current sheets.

Generation of high-speed electron outflows and energy dissipation.

Abstract

In this paper, by performing a two-dimensional particle-in-cell simulation, we investigate magnetic reconnection in the downstream of a quasi-perpendicular shock. The shock is nonstationary, and experiences a cyclic reformation. At the beginning of reformation process, the shock front is relatively flat, and part of upstream ions are reflected by the shock front. The reflected ions move upward in the action of Lorentz force, which leads to the upward bending of magnetic field lines at the foot of the shock front, and then a current sheet is formed due to the squeezing of the bending magnetic field lines. The formed current sheet is brought toward the shock front by the solar wind, and the shock front becomes irregular after interacting with the current sheet. Both the current sheet brought by the solar wind and the current sheet associated with the shock front are then fragmented into many small filamentary current sheets. Electron-scale magnetic reconnection may occur in several of these filamentary current sheets when they are convected into the downstream, and magnetic islands are generated. A strong reconnection electric field and energy dissipation are also generated around the X line, and high-speed electron outflow is also formed.