Structures of Hall Fields in Asymmetric Magnetic Reconnection

Abstract

AbstractUnlike a quadrupolar Hall magnetic field in symmetric magnetic reconnection, a bipolar or quadrupolar Hall magnetic field occurs in asymmetric reconnection as indicated by recent observations from the Magnetospheric Multiscale (MMS) mission. Here we present analytic calculations of the structures of Hall magnetic fields in asymmetric reconnection. The Hall magnetic fields are analyzed in terms of kinetic Alfvén wave eigenmodes of the reconnection layer. The bipolar and quadrupolar patterns of Hall magnetic fields correspond to a dominance of the n = 0 and n = 1 kinetic Alfvén wave eigenmode, respectively. The asymmetry of Hall fields is linked to the asymmetry of the Alfvé speed profile. The Hall magnetic fields are shifted toward and enhanced on the low Alfvén speed side of the reconnection layer. The asymmetry in the magnetic field strength of the reconnection layer has a major effect on the structures of Hall magnetic fields.