Effects of Multi-scale Coupling on Particle Acceleration and Energy Partition in Magnetic Reconnection

TL;DR

This study uses particle-in-cell simulations to explore how multi-scale interactions during magnetic reconnection influence particle acceleration and energy distribution, revealing the importance of secondary current sheets and turbulence in energy dissipation.

Contribution

It demonstrates the impact of multi-scale coupling on particle acceleration and energy partitioning in relativistic magnetic reconnection, highlighting the role of secondary current sheets and turbulence.

Findings

Secondary current sheets dominate energy dissipation in large systems.

Turbulence enhances non-thermal particle populations.

Multi-scale dynamics alter particle energy spectra.

Abstract

The interplay between kinetic and macroscopic scales during magnetic reconnection is investigated using particle-in-cell simulations of magnetic island coalescence in the strongly-magnetized, relativistic pair plasma regime. For large system sizes, secondary current sheet formation and downstream turbulence driven by the reconnection outflows dominate the global energy dissipation so that it is causally connected, but spatially and temporally de-coupled from the primary reconnecting current sheet. When compared to simulations of an isolated, force-free current sheet, these dynamics activate additional particle acceleration channels which are responsible for a significant population of the non-thermal particles, modifying the particle energy spectra.