We present new developments on the Cosmic--Ray driven, galactic dynamo, modeled by means of direct, resistive CR--MHD simulations, performed with ZEUS and PIERNIK codes. The dynamo action, leading to the amplification of large--scale galactic magneti
c fields on galactic rotation timescales, appears as a result of galactic differential rotation, buoyancy of the cosmic ray component and resistive dissipation of small--scale turbulent magnetic fields. Our new results include demonstration of the global--galactic dynamo action driven by Cosmic Rays supplied in supernova remnants. An essential outcome of the new series of global galactic dynamo models is the equipartition of the gas turbulent energy with magnetic field energy and cosmic ray energy, in saturated states of the dynamo on large galactic scales.
We conduct a series of magnetohydrodynamical (MHD) simulations of magnetized interstellar medium (ISM) disturbed by exploding stars. Each star deposits a randomly oriented, dipolar magnetic field into ISM. The simulations are performed in a Cartesian
box, in a reference frame that is corotating with the galactic disk. The medium is stratified by vertical galactic gravity. The resulting turbulent state of ISM magnetized by the stellar explosions is processed with the aid of Fourier analysis. The results leads to the conclusion that the input of magnetic energy from exploding stars is additionally multiplied by differential rotation. The resulting magnetic field appears to grow up in small-scale component, while the total magnetic flux remains limited. Our results indicate that magnetic field originating from exploding stars can be a source of initial magnetic fields for a subsequent dynamo process.
