3D magnetic reconnection in relativistic pair plasma with moderate magnetization

Magnetic reconnection is a fundamental plasma process that converts magnetic field energy to particle kinetic energy. Relativistic reconnection is of particular interest in astrophysical contexts because it can accelerate particles to high energies where they can emit observable radiation. While reconnection is typically thought of as an essentially 2D process, 3D effects can potentially interfere with reconnection. Using particle-in-cell simulations, we find -- for relativistic pair-plasma reconnection with magnetization σ_h∼1, where σ_h is roughly the ratio of magnetic to plasma energy -- that 3D effects (including the drift-kink instability) can substantially disrupt reconnection, e.g., distorting and thickening the current layer, altering the reconnection rate. This contrasts starkly with the σ_h»1 regime, where 3D effects occur without significantly changing overall reconnection morphology or energetics. Intriguingly, despite 3D processes interfering with reconnection in the σ_h∼1 regime, nonthermal particle acceleration (NTPA) remains robust, and is even enhanced relative to 2D (although NTPA for σ_h∼1 is less efficient than for σ_h»1 in both 2D and 3D).