Global galactic dynamo driven by cosmic-rays and exploding magnetized
  stars
  We report first results of first global galactic-scale CR-MHD simulations of
cosmic-ray-driven dynamo. We investigate the dynamics of magnetized
interstellar medium (ISM), which is dynamically coupled with the cosmic-ray
(CR) gas. We assume that exploding stars deposit small-scale, randomly
oriented, dipolar magnetic fields into the differentially rotating ISM,
together with a portion of cosmic rays, accelerated in supernova shocks. We
conduct numerical simulations with the aid of a new parallel MHD code PIERNIK.
We find that the initial magnetization of galactic disks by exploding
magnetized stars forms a favourable conditions for the cosmic-ray-driven
dynamo. We demonstrate that dipolar magnetic fields supplied on small
SN-remnant scales, can be amplified exponentially, by the CR-driven dynamo, to
the present equipartition values, and transformed simultaneously to large
galactic-scales. The resulting magnetic field structure in an evolved galaxy
appears spiral in the face-on view and reveals the so called X-shaped structure
in the edge-on view.
