Turbulence and Magnetic Fields in the Large Scale Structure of the Universe

TL;DR

This paper proposes a physical model where turbulence generated by cosmological shocks amplifies magnetic fields in the universe's large scale structure, with simulations supporting the estimated field strengths in different cosmic environments.

Contribution

It introduces a scenario linking turbulence and magnetic field amplification to cosmological shocks during large scale structure formation, supported by supercomputer simulations.

Findings

Turbulence is subsonic inside galaxy clusters.

Magnetic fields reach microgauss levels in clusters.

Filaments have magnetic fields around 10 nanogauss.

Abstract

The nature and origin of turbulence and magnetic fields in the intergalactic space are important problems that are yet to be understood. We propose a scenario in which turbulent flow motions are induced via the cascade of the vorticity generated at cosmological shocks during the formation of the large scale structure. The turbulence in turn amplifies weak seed magnetic fields of any origin. Supercomputer simulations show that the turbulence is subsonic inside clusters/groups of galaxies, whereas it is transonic or mildly supersonic in filaments. Based on a turbulence dynamo model, we then estimate that the average magnetic field strength would be a few microgauss inside clusters/groups, approximately 0.1 microgauss around clusters/groups, and approximately 10 nanogauss in filaments. Our model presents a physical mechanism that transfers the gravitation energy to the turbulence and magnetic field energies in the large scale structure of the universe.