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 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.