Galactic winds driven by cosmic rays

Cosmic rays (CR) are accelerated to relativistic energies in supernova remnants. According to standard estimations about 10% of supernova (SN) kinetic energy output is converted into energy of charged CR particles. The energy accumulated in CRs is sufficient to drive galactic winds, although the standard picture attributes the wind phenomenon to the expansion of interstellar gas heated in SN remnants. The physical properties of thermal winds and CR-driven winds are different, however. Numerical simulation models show that galactic winds driven by cosmic rays are cooler, smoother and slower then the winds driven by thermal gas. The models demonstrate also, that CR-driven winds lead to the formation of spiral magnetic field structures in galactic halos which are observed as X-shape structure in polarized synchrotron emission. I am going to discuss the significance of CR driven winds for the formation of disk galaxies.