Magnetic reconnection on the ion-skin-depth scale in the dusty magnetotail of a comet

Abstract

Resistive magnetic reconnection is studied in a dusty plasma configuration without a guide magnetic field, typical for cometary tails. For a high-β plasma (β∼1) consisting of electrons, ions, and immobile dust grains that constitute a neutralizing background, a two-fluid description is used to study electromagnetic perturbations with the frequency below the ion gyrofrequency, propagating at an arbitrary angle relative to the background magnetic field and including the effects of the Hall current. The perturbations consist of both the compressional and torsional components of the magnetic field, as well as of the acoustic perturbations and the electrostatic potential. The symmetry breaking between electrons and ions, introduced by the presence of dust grains, gives rise to an E×B current in the unperturbed state which can support an antiparallel magnetic field configuration even in a cold plasma. In the perturbed state, the emergence of a new electromagnetic mode in a dusty plasma, which is evanescent be...