Collisionless magnetic reconnection in a five-moment two-fluid electron-positron plasma

Abstract

We simulate magnetic reconnection in electron-positron (pair) plasma using a collisionless two-fluid model with isotropic pressure. In this model the resistive, Hall, and electrokinetic pressure terms are absent from the curl of Ohm's law, leaving the inertial term alone to provide for magnetic reconnec- tion. Our simulations suggest that for pair plasma simulated with isotropic pressure fast reconnection does not occur without the aid of sufficient (numer- ical) diffusion. We contrast this result with simulations and published results showing fast reconnection for collisionless two-fluid plasma with isotropic pres- sures and non-canceling mass-to-charge ratios, where Hall effects are present and numerical diffusion is small, and with published PIC studies of pair plasma which observe fast reconnection and attribute it to nonisotropic pressure.