Magnetic fields in barred galaxies

II. Dynamo models

¹ Department of Mathematics, University of Manchester, Manchester M13 9PL, UK
² Department of Mathematics, University of Newcastle, Newcastle on Tyne NE1 7RU, UK
³ Department of Physics, Moscow State University, Moscow 19899, Russia
⁴ Max Planck Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany

Corresponding author: D. Moss, anvar.shukurov@newcastle.ac.uk

Received: 5 July 2001
Accepted: 24 September 2001

Abstract

We study the generation and maintenance of large-scale magnetic fields in barred galaxies. We take a velocity field (with strong noncircular components) from a published gas dynamical simulation of Athanassoula (1992), and use this as input to a galactic dynamo calculation. Our work is largely motivated by recent high quality VLA radio observations of the barred galaxy NGC 1097, and we compare our results in detail with the regular magnetic fields deduced from these observations. We are able to reproduce most of the conspicuous large-scale features of the observed regular field, including the field structure in the central regions, by using a simple mean-field dynamo model in which the intensity of interstellar turbulence (more precisely, the turbulent diffusivity) is enhanced by a factor of 2-6 in the dust lanes and near the circumnuclear ring. We argue that magnetic fields can be dynamically important, and therefore should be included in models of gas flow in barred galaxies.