Parker Instability with Coriolis Force and Magnetic Reconnection as a Part of the Galactic Fast Dynamo Action

Abstract

In the present paper, we investigate the influence of the Coriolis force and magnetic reconnection on the evolution of the Parker instability in galactic disks. We apply a model of a local gas cube, permeated by an azimuthal large-scale magnetic field and solve numerically resistive 3D MHD equations with the contribution of Coriolis force. We introduce a current dependent resistivity which switches on the magnetic reconnection above a certain critical current density. Our main goal is to study the magnetic field topology and the formation of large scale poloidal magnetic fields from the initial azimuthal field. Our simulations demonstrate that the Parker instability leads to the formation of helically twisted magnetic flux tubes which are next agglomerated by reconnection forming significant poloidal magnetic field component on the scale of the whole cube. Such an evolution represents a kind of the fast dynamo process as proposed by (1992).