The Extent of Power-Law Energy Spectra in Collisionless Relativistic Magnetic Reconnection in Pair Plasmas

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 , 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.