Cosmic-ray driven dynamo in spiral galaxies
In the present paper we construct maps of polarized synchrotron radio emission
of a whole galaxy, based on local models of the cosmic ray (CR) driven dynamo.
We perform numerical simulations of the dynamo in local Cartesian domains, with
shear-periodic boundary conditions, placed at the different galactocentric
radii. Those local solutions are concatenated together to construct the
synchrotron images of the whole galaxy. The main aim of the paper is to compare
the model results with the observed radio continuum emission from nearly
edge-on spiral galaxy.
On the basis of the modeled evolution of the magnetic field structure, the
polarization maps can be calculated at different time-steps and at any
orientation of the modeled galaxy. For the first time self-consistent
cosmic-ray electron distribution is used to integrate synchrotron emissivity
along the line of sight. Finally, our maps are convolved with the given
radiotelescope beam. We show that it is possible to reconstruct the extended
magnetic halo structures of the edge-on galaxies (so called X-shaped
structures).