Galactic winds and the symmetry properties of galactic magnetic fields

Abstract

Context. Contemporary studies of the symmetry properties of galactic magnetic fields contain two contradictory ideas. There are observational and theoretical hints that large-scale magnetic fields are symmetric with respect to the galactic plane in the disc, and antisymmetric in the halo. On the other hand, standard galactic dynamo models without a galactic wind give symmetric or antisymmetric configurations in both disc and halo regions simultaneously. Aims. Here we explore the role of a galactic wind in resolving this dichotomy. Methods. The key idea is that a galactic wind must be be taken into account in order to resolve the problem. We perform a search of the parameter space of galactic dynamo models containing such winds. Results. By including a galactic wind, magnetic configurations of such symmetry, i.e. approximately even in the disc and odd in the halo, can be obtained. We note that a variety of other solutions can also be found. Conclusions. A galactic wind plays a significant role in determining the structure of galactic magnetic configurations and should be included in future modelling. © ESO, 2010.