Particle acceleration in three-dimensional tearing configurations

In three-dimensional electromagnetic configurations that result from unstable resistive tearing modes, particles can be efficiently accelerated to relativistic energies. To prove this, resistive magnetohydrodynamic simulations are used as input configurations for successive test particle simulations. The simulations show the capability of three-dimensional nonlinearly evolved tearing modes to accelerate particles perpendicular to the plane of the reconnecting magnetic field components. The simulations differ considerably from analytical approaches by involving a realistic three-dimensional electric field with a nonhomogeneous component parallel to the current direction. The resulting particle spectra exhibit strong pitch-angle anisotropies. Typically, about 5%-8% of an initially Maxwellian distribution is accelerated to the maximum energy levels given by the macroscopic generalized electric potential structure. Results are shown for both, nonrelativistic particle acceleration that is of interest, e.g., in the context of auroral arcs and solar flares, and relativistic particle energization that is relevant, e.g., in the context of active galactic nuclei. (C) 2003 American Institute of Physics.