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

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 $σ$ and system sizes $L$. The particle spectra are well-represented by a power law $γ^{-α}$, with a combination of exponential and super-exponential high-energy cutoffs, proportional to $σ$ and $L$, respectively. For large $L$ and $σ$, the power-law index $α$ approaches about 1.2.

12 pages, 6 figures