The role of star formation for the galactic dynamo

TL;DR

This paper investigates how star formation influences galactic magnetic field amplification through dynamo processes, deriving scaling laws from simulations and applying them to global galaxy models.

Contribution

It introduces scaling laws for turbulent transport coefficients based on SN-driven turbulence, linking star formation rates to magnetic field evolution in galaxies.

Findings

Magnetic field amplification aligns with mean-field theory.

Scaling laws depend on SN rate, density, and rotation.

Global models reproduce observed galactic magnetic structures.

Abstract

Magnetic field amplification by a fast dynamo is seen in local box simulations of SN-driven ISM turbulence, where the self-consistent emergence of large-scale fields agrees very well with its mean-field description. We accordingly derive scaling laws of the turbulent transport coef- ficients in dependence of the SN rate, density and rotation. These provide the input for global simulations of regular magnetic fields in galaxies within a mean-field MHD framework. Using a Kennicutt-Schmidt relation between the star formation (SF) rate and midplane density, we can reduce the number of free parameters in our global models. We consequently present dynamo models for different rotation curves and radial density distributions.