Two-Fluid Magnetohydrodynamic Simulations of Relativistic Magnetic Reconnection

TL;DR

This paper uses a relativistic two-fluid MHD simulation to study magnetic reconnection in electron-positron plasmas, revealing faster reconnection rates and stable Petschek-type structures over long times.

Contribution

It introduces an inter-species friction force as an effective resistivity and demonstrates the occurrence of Petschek-type reconnection in a relativistic two-fluid system.

Findings

Reconnection rate can reach ~1 in extreme cases.

Petschek-type bifurcated current layers are stable over long periods.

Narrower outflow channels occur with higher magnetic energy inflow.

Abstract

We investigate the large scale evolution of a relativistic magnetic reconnection in an electron-positron pair plasma by a relativistic two-fluid magnetohydrodynamic (MHD) code. We introduce an inter-species friction force as an effective resistivity to dissipate magnetic fields. We demonstrate that magnetic reconnection successfully occurs in our two-fluid system, and that it involves Petschek-type bifurcated current layers in later stage. We further observe a quasi-steady evolution thanks to an open boundary condition, and find that the Petschek-type structure is stable over the long time period. Simulation results and theoretical analyses exhibit that the Petschek outflow channel becomes narrower when the reconnection inflow contains more magnetic energy, as previously claimed. Meanwhile, we find that the reconnection rate goes up to ~1 in extreme cases, which is faster than previously thought. The role of the resistivity, implications for reconnection models in the magnetically dominated limit, and relevance to kinetic reconnection works are discussed.