Signatures of collisionless magnetic reconnection

Simulations of magnetic reconnection in simple systems without a guide field predict the formation of a spatially antisymmetric out‐of‐plane magnetic field signature and a symmetric perturbation in the plasma pressure. Here we show, using two fluid simulations and analytic arguments, that these signatures are not in fact a generic feature of fast reconnection. Rather, in the strong guide field limit the pressure perturbation becomes antisymmetric, while the perturbation in the out‐of‐plane field can be either symmetric for βx ∼ 1 or antisymmetric for βx ≫ 1, where βx is the plasma β defined using the reconnection magnetic field just upstream of the reconnection region.