Computer studies on noncoplanar slow and intermediate shocks associated with the sheared fast reconnection mechanism

It was recently found that noncoplanar slow shocks stood in the sheared fast reconnection configuration. Hence, the present one-dimensional magnetohydrodynamics (MHD) simulations with high numerical resolution study the temporal dynamics of MHD shocks, from a slow shock to a weak intermediate shock, that are placed in a noncoplanar situation. It is shown that for any case the noncoplanar shock structure can be sustained by physical dissipations involved. The resulting noncoplanar slow shock structure is, both qualitatively and quantitatively, in good agreement with the two-dimensional shock transition layer associated with the sheared fast reconnection mechanism. The one-dimensional noncoplanar slow or (subfast) intermediate shock structure is eventually bifurcated into an intermediate wave and a coplanar slow shock as a result of magnetic field rotation. In general, any stable shock must be coplanar, and in actual systems strictly coplanar boundary conditions ahead of and behind a shock cannot be provided nor sustained. Hence we propose a criterion, required for a stable shock to be realized, such that the (coplanar) shock must survive and hence be derived as an eventual solution in noncoplanar situations. It is argued that the present simulation results as well as the previous ones should be interpreted and reconsidered on the basis of this criterion.