Nonlinear explosive magnetic reconnection in a collisionless system

The debate surrounding fast magnetic energy dissipation by magnetic reconnection has remained a fundamental topic in the plasma universe, not only in the Earth's magnetosphere but also in astrophysical objects such as pulsar magnetospheres and magnetars, for more than half a century. Recently, nonthermal particle acceleration and plasma heating during reconnection have been extensively studied, and it has been argued that rapid energy dissipation can occur for a collisionless thin current sheet, the thickness of which is of the order of the particle gyroradius. However, it is an intriguing enigma as to how the fast energy dissipation can occur for a thick current sheet with thickness larger than the particle gyroradius. Here we demonstrate, using a high-resolution particle-in-cell simulation for a pair plasma, that an explosive reconnection can emerge with the enhancement of the inertia resistivity due to the magnetization of the meandering particles by the reconnecting magnetic field and the shrinkage of the current sheet. In addition, regardless of the initial thickness of the current sheet, the timescale of the nonlinear explosive reconnection is tens of the Alfven transit time. Published under an exclusive license by AIP Publishing.

Automated summary

The debate on fast magnetic energy dissipation through magnetic reconnection has been ongoing for over half a century, with recent studies indicating rapid dissipation in collisionless thin current sheets but posing an enigma for thick current sheets. High-resolution particle-in-cell simulations show explosive reconnection in pair plasma due to inertia resistivity enhancement and current sheet shrinkage, with its timescale being tens of the Alfven transit time regardless of initial thickness.