Magnetic dynamo action in astrophysical turbulence

TL;DR

This paper studies how turbulent velocity fluctuations amplify magnetic fields in astrophysical environments using the Kazantsev-Kraichnan model, providing numerical solutions for spectra and growth rates across various physical regimes.

Contribution

It offers the first comprehensive numerical analysis of magnetic field amplification considering different Prandtl numbers and helicity conditions within the Kazantsev-Kraichnan framework.

Findings

Numerical spectra and growth rates for magnetic fluctuations are obtained.

Amplification mechanisms vary with magnetic Prandtl number and helicity.

Results are relevant for understanding magnetic field generation in astrophysics.

Abstract

We investigate the structure of magnetic field amplified by turbulent velocity fluctuations, in the framework of the kinematic Kazantsev-Kraichnan model. We consider Kolmogorov distribution of velocity fluctuations, and assume that both Reynolds number and magnetic Reynolds number are very large. We present the full numerical solution of the model for the spectra and the growth rates of magnetic fluctuations. We consider astrophysically relevant limits of large and small magnetic Prandtl numbers, and address both helical and nonhelical cases.