S E M I N A R IDepartament d'Astronomia i Astrofísica
Universitat de València
Cosmic-Ray driven dynamo in galactic disks
Centre for Astronomy, Nicolaus Copernicus University, Torun, Polònia
Seminari del departament d'Astronomia i Astrofísica
Dijous 24 juny 2010
I am going to present recent developments of local and global, galactic-scale numerical models, of the Cosmic-Ray driven dynamo, which was originally proposed by Parker (1992). We conduct global, galactic-scale CR-MHD numerical simulations of the dynamics of interstellar medium, composed of gas, magnetic-field, and cosmic-ray components. We take into account cosmic rays, accelerated in randomly distributed supernova remnants, and assume that supernovae deposit small-scale, randomly oriented, dipolar magnetic-fields into the ISM. We find that, the magnetization of galactic disks by exploding magnetized stars forms a favorable initial condition for the galactic dynamo process. The amplification timescale of the large-scale magnetic field, resulting from the CR-driven dynamo, is comparable to the galactic rotation period. The process converts efficiently small-scale magnetic fields of SN-remnants into the galactic-scale magnetic fields. The resulting magnetic-field structure resembles the observed X-shaped magnetic fields in edge-on galaxies.