The formation of power-law energy spectrum in 3D low-beta magnetic reconnection
ORAL
Abstract
Magnetic reconnection has been proposed as a theory for explaining particle acceleration in solar flares. However, previous kinetic simulations of non-relativistic reconnection have not been able to obtain a power-law energy spectrum, which is a key observational feature of particle distribution. Here we present results from 3D fully kinetic particle-in-cell simulations of reconnection in the non-relativistic low-beta regime. We show that a clear power-law energy spectrum can form and sustain extensively during the simulation. Comparing with 2D simulations, where high-energy particles are trapped deep in magnetic islands, 3D simulations enable stronger acceleration for high-energy particles due to stochastic magnetic field lines and wave-particle scattering of high-energy particles. These effects lead to a nearly constant acceleration rate for particles at different energies. The power-law index is a balance of particle acceleration and particle escape from major acceleration region. This study clarifies the formation condition of power-law energy spectrum in a reconnection layer and has important implication for understanding particle energization during solar flares.
*We acknowledges support in part from the U.S. Department of Energy, Office of Science, Office of Fusion Energy Science and from NASA grant NNH16AC60I. We also acknowledge support by the DOE through the LDRD program at LANL.
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