Star Formation and Galaxy Dynamo Equations with Random Coefficients

Abstract

We study the influence of star formation on magnetic field in galaxies. Two approaches have been used to describe this mechanism. The first one uses some averaged approximate kinematic characteristics that appear in the galactic dynamo equations. We use the so-called no-z model that takes into account the fact that galactic disks are quite thin and hence we can consider only the field components that are parallel to the plane of the galaxy. We also use the equation that describes the evolution of magnetic helicity, which can be important for galaxies with intensive star formation. The second approach uses the dynamo equations with random coefficients, which are useful for describing magnetic fields in galaxies with rapidly changing kinematic parameters. Both methods yield similar results: if the surface star formation rate is small, the magnetic field evolution does not change very much. If the surface star formation rate is more than five times higher than in the Milky Way, the field decays.

Keywords

• stars: formation
• galaxies: magnetic fields
• ism: magnetic fields