Reconnection layers in two-dimensional magnetohydrodynamics and comparison with the one-dimensional Riemann problem

Abstract

The outflow region of fast magnetic reconnection is studied by using a two-dimensional (2-D) resistive magnetohydrodynamic (MHD) model. The effects of the guide magnetic field By on the 2-D quasi-steady reconnection are investigated. The one-dimensional (1-D) MHD Riemann problem associated with the magnetic reconnection is also simulated for comparison. In the 2-D reconnection a trailing reconnection layer is formed behind a leading bulge. In the cases with By=0, intermediate shocks, slow shocks, slow expansion waves, and a contact discontinuity may be present in the quasi-steady reconnection layer. In general cases with By≠0, the intermediate shocks are replaced by time-dependent intermediate shocks (TDISs). The structure of the reconnection layer as a function of the distance z from the X line in the 2-D reconnection is found to be related to the 1-D simulation results as a function of time t.