The extent of power-law energy spectra in collisionless relativistic magnetic reconnection in pair plasmas

TL;DR

This study uses particle-in-cell simulations to analyze how particles gain energy during relativistic magnetic reconnection in pair plasmas, revealing power-law spectra with cutoffs influenced by system size and magnetization.

Contribution

It provides a comprehensive characterization of particle energy spectra in relativistic reconnection across various magnetizations and system sizes, highlighting the spectral index and cutoff behaviors.

Findings

Power-law spectra with exponential cutoffs are observed.

Spectral index approaches ~1.2 for large system sizes and magnetizations.

High-energy cutoffs scale with system size and magnetization.

Abstract

Using two-dimensional particle-in-cell simulations, we characterize the energy spectra of particles accelerated by relativistic magnetic reconnection (without guide field) in collisionless electron-positron plasmas, for a wide range of upstream magnetizations $\sigma$ and system sizes $L$. The particle spectra are well-represented by a power law $\gamma^{-\alpha}$, with a combination of exponential and super-exponential high-energy cutoffs, proportional to $\sigma$ and $L$, respectively. For large $L$ and $\sigma$, the power-law index $\alpha$ approaches about 1.2.