Electron Acceleration during Macroscale Magnetic Reconnection

TL;DR

This paper presents the first self-consistent simulations of electron acceleration during macroscale magnetic reconnection, revealing power-law spectra consistent with solar flare observations and identifying the role of guide fields.

Contribution

It introduces self-consistent simulations of electron acceleration in macroscale reconnection, highlighting the influence of guide fields on nonthermal electron production.

Findings

Power-law electron spectra extend over two decades in energy.

Guide fields suppress nonthermal electron production.

Nonthermal electrons dominate energy content in weak guide field scenarios.

Abstract

The first self-consistent simulations of electron acceleration during magnetic reconnection in a macroscale system are presented. Consistent with solar flare observations the spectra of energetic electrons take the form of power-laws that extend more than two decades in energy. The drive mechanism for these nonthermal electrons is Fermi reflection in growing and merging magnetic flux ropes. A strong guide field is found to suppress the production of nonthermal electrons by weakening the Fermi drive mechanism. For a weak guide field the total energy content of nonthermal electrons dominates that of the hot thermal electrons even though their number density remains small. Our results are benchmarked with the hard x-ray, radio and extreme ultra-violet (EUV) observations of the X8.2-class solar flare on September 10, 2017.