Dynamics of relativistic reconnection

The dynamics of the steady state Sweet-Parker-type reconnection is analyzed in the relativistic regime when energy density in the in. owing region is dominated by the magnetic field. The structure of the reconnection layer ( its thickness and inflow and outflow velocities) depends on the ratio of two large dimensionless parameters of the problem: the magnetization parameter sigma much greater than 1 ( the ratio of the magnetic to particle energy densities in the in. owing region) and the Lundquist number S. The inflow velocity may be relativistic (for S < σ) or nonrelativistic (for S > sigma), while the out. owing plasma is always moving relativistically. For extremely magnetized plasmas with sigma greater than or equal to S-2, the inflow four-velocity becomes of the order of the Alfven four-velocity.