Hybrid simulations of magnetic reconnection initiated in the magnetosheath

Abstract

Interaction of solar wind tangential discontinuities (TDs) with the bow shock may initiate reconnection in the magnetosheath. We employ 2.5-D electromagnetic, hybrid simulations that treat the ions kinetically via particle-in-cell methods and the electrons as a massless fluid to study this interaction. We present results from eight runs corresponding to TD thicknesses ranging from 10 to 260 ion skin depths and shear angles ranging from 120° to 180°. Our results indicate a transition from time-dependent to steady state reconnection as the thickness of the solar wind TD increases above 30 ion skin depths. As the shear angle in the magnetic field decreases, it takes longer to initiate reconnection, and reconnection jet speeds diminish, suggesting a lower reconnection rate. Implications of these results for magnetic reconnection at currents sheets in general and at the magnetopause in particular are also discussed.