Orateur
Dr
Michal Hanasz
Description
I am going to review recent developments of local and global, galactic-scale numerical models, of the Cosmic-Ray-driven dynamo, which was originally proposed by Parker (1992). The concept of Cosmic-Ray driven MHD dynamo relies on buoyancy forces induced by the presence of cosmic rays in the interstellar medium. The CR-driven dynamo models are realized by means of direct CR-MHD numerical simulations of the dynamics of interstellar medium, composed of gas, magnetic-field, and Cosmic Rays. It is assumed that Cosmic Rays are accelerated in randomly distributed supernova remnants, and that supernovae deposit small-scale, randomly oriented, dipolar magnetic-fields into the ISM. Numerical experiments show that galactic magnetic fields are amplified to the equipartition values on timescales comparable to the rotation period of the galaxy. The amplification process is associated with efficient conversion of small-scale magnetic fields of SN-remnants into the galactic-scale magnetic fields. The resulting magnetic field reveals a spiral structure in face-on views, and it resembles the observed X-shaped magnetic fields in edge-on galaxies.
