Initial Magnetization of Galaxies by Exploding, Magnetized Stars

TL;DR

This study uses MHD simulations to explore how exploding, magnetized stars contribute to the initial magnetic fields in galaxies, highlighting the amplification effects of differential rotation and the small-scale growth of magnetic fields.

Contribution

It demonstrates that stellar explosions can seed galactic magnetic fields, which are then amplified by differential rotation, providing insights into the origin of galactic magnetism.

Findings

Magnetic energy from stars is amplified by galactic differential rotation.

Magnetic fields grow predominantly in small-scale components.

Stellar explosions can serve as initial magnetic field sources for dynamos.

Abstract

We conduct a series of magnetohydrodynamical (MHD) simulations of magnetized interstellar medium (ISM) disturbed by exploding stars. Each star deposits a randomly oriented, dipolar magnetic field into ISM. The simulations are performed in a Cartesian box, in a reference frame that is corotating with the galactic disk. The medium is stratified by vertical galactic gravity. The resulting turbulent state of ISM magnetized by the stellar explosions is processed with the aid of Fourier analysis. The results leads to the conclusion that the input of magnetic energy from exploding stars is additionally multiplied by differential rotation. The resulting magnetic field appears to grow up in small-scale component, while the total magnetic flux remains limited. Our results indicate that magnetic field originating from exploding stars can be a source of initial magnetic fields for a subsequent dynamo process.