Helical randomization of magnetized Galactic and galaxy clusters plasmas: from magnetorotational disc dynamo to the Faraday rotation and synchrotron emission skies

TL;DR

This paper demonstrates that the transition from chaos to turbulence in magnetized galactic plasmas involves a randomization process linked to magnetic helicity, affecting observable phenomena like Faraday rotation and synchrotron emission.

Contribution

It introduces the concept of distributed chaos to describe plasma randomization and connects magnetic helicity to observable magnetic field effects in galaxies and clusters.

Findings

Randomization correlates with magnetic helicity and dissipation rate.

Numerical simulations agree with observational data.

Spontaneous symmetry breaking generates local helicity.

Abstract

Using results of numerical simulations and Galactic and galaxy clusters observations, it is shown that the transition from deterministic chaos to hard turbulence in the Galactic and galaxy clusters magnetized plasmas occurs via 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. Spontaneous breaking of local reflectional symmetry (an intrinsic property of chaotic/turbulent motions) generates local helicity even when the global helicity is negligible. It is shown that the magnetic fields can impose their level of randomization on the electron density, Faraday rotation maps, and synchrotron emission. Results of the numerical simulations of the Galactic and galaxy clusters 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 and synchrotron emission skies.