The evolution of dynamo maintained magnetic fields in a barred spiral galaxy

Wemodel the evolution of dynamomaintained magnetic fields in a barred spiral galaxy. The velocity fields are taken from N-body dynamical simulations. The important feature is the presenceof strong, unsteadynon-circular gasmotions, driven by the central bar, The nonlinear dynamo calculations are carried out with both two dimensional (thin disc approximation) and three dimensional codes. The resulting magnetic field shows repeated episodeswith approximately ring-like structure, and structure with short spiral arms. These morphological features appear robust, in that velocity data from distinct dynamical simulations gives rise to similar structures.