Influence of Hall effect on reconnection in turbulence

The statistical study of magnetic reconnection events in two-dimensional turbulence has been performed comparing numerical simulations of magnetohydrodynamics (MHD) and Hall magnetohydrodynamics (HMHD). The analysis confirm that the Hall term plays an important role in turbulence, where magnetic islands simultaneously reconnect in a complex way. In particular, increase of the Hall parameter, the ratio between the ion skin depth and the system size, causes the distribution of reconnection rates to become broader than in the MHD case, and increases the frequency of occurrence of the highest values of reconnection rate. Moreover, in HMHD the local geometry of the reconnection region changes, manifesting bifurcated current sheets and quadrupolar magnetic field structures, leading locally to faster reconnection processes. This study supports the idea that turbulence, together with small-scale effects, is responsible for the fast reconnection events commonly observed in nature.