Dynamical Friction in a magnetized gas

TL;DR

This paper analytically investigates the flow structure and dynamical friction experienced by a gravitating mass moving subsonically in a magnetized, isothermal medium, revealing magnetic effects reduce density and friction force.

Contribution

It provides the first analytical solutions for density and velocity perturbations in a magnetized medium under subsonic motion, highlighting magnetic influence on dynamical friction.

Findings

Magnetic fields decrease the density around the moving mass.

Dynamical friction force diminishes with increasing magnetic field strength.

Solutions are valid when the Alfvén velocity is less than the accretor's velocity.

Abstract

When a gravitating point mass moves subsonically through a magnetized and isothermal medium, the dynamical structure of the flow is studied far from the mass using a perturbation analysis. Analytical solutions for the first-order density and the velocity perturbations are presented. Validity of our solutions is restricted to the cases where the Alfven velocity in the ambient medium is less than the accretor's velocity. The density field is less dense because of the magnetic effects according to the solutions and the dynamical friction force becomes lower as the strength of the magnetic field increases.