Helical randomization of magnetized Galactic plasmas: from magnetorotational disc dynamo to the Faraday rotation sky

Abstract

It is shown, using results of numerical simulations and galactic observations that the transition from deterministic chaos to hard turbulence in the Galactic magnetized plasmas (global and those generated in the internal accretion disk in the high-energy surrounding of a supermassive black hole at the Galactic center) happens through a randomization process. The notion of distributed chaos has been used to describe the randomization process. The randomization can be quantified with the main parameter of the distributed chaos which in turn can be related to magnetic helicity or its dissipation rate. The magnetic fields can impose their level of randomization on the electron density. Results of the numerical simulations of the Galactic dynamos: the inner disk's ones (based on the magnetorotational instability) and global ones, are in good agreement with this approach, as well as with the results obtained using observations of the Faraday rotation sky.