Low-frequency waves in magnetic reconnection

Abstract

The characteristics of low-frequency waves in magnetic reconnection are studied using two-dimensional hybrid simulation code. In a coordinate system moving with fluid, the time series of a magnetic field perpendicular to the magnetic reconnection plane, B y , is transformed into the power spectrum via fast Fourier transformation, while the wave propagation direction and polarization are determined by minimum variance analysis of the electric field. The results show that low-frequency Alfvén ion-cyclotron waves dominate the reconnection area. These waves have frequencies 0–1Ωp (where Ωp is the local proton gyro frequency) and all are left-handed circularly polarized. Among these waves, large-amplitude turbulence, with frequencies of 0–0.6Ωp and isotropic propagation, dominates the outflow regions. This can cause the reversal of B y in the quadrupole structure. In the inflow regions, dominant waves, propagating mainly parallel to the ambient magnetic field, have higher frequencies and smaller amplitudes. The frequency of the main peak of wave energy is usually higher than 0.5Ωp.