Conditions for relativistic magnetic reconnection onset under the presence of shear flows and a guide field*

The  scaling of onset and growth of magnetic reconnection in relativistic plasma is investigated in the presence of shear flows parallel to the reconnecting magnetic field, and an out-of-plane guide field, using 2D PIC simulations. Shear flows are found to suppress reconnection as they approach a critical velocity, and unlike in the non-relativistic limit, the addition of a guide field lowers the in-plane Alfven velocity, contributing to more efficient suppression. As the critical velocity is approached, shear flows also delay the onset time of fast reconnection and both shear flow and guide field slow initial growth.