Astrophysical explosions revisited: collisionless coupling of debris to magnetized plasma

TL;DR

This paper investigates how ionized debris from astrophysical explosions interacts with magnetized plasma using hybrid simulations, deriving scaling laws and analyzing debris escape and coupling.

Contribution

It introduces a hybrid simulation approach to study debris-plasma coupling and derives scaling laws for debris cloud size and escape fraction.

Findings

Debris escape fraction increases with gyroradius.

Scaling laws relate debris mass and explosion speed to cloud size.

Heavy debris species influence collisionless coupling dynamics.

Abstract

The coupling between a rapidly expanding cloud of ionized debris and an ambient magnetized plasma is revisited with a hybrid (kinetic ion/fluid electron) simulation code that allows a study over a wide range of plasma parameters. Over a specified range of hypothetical conditions, simple scaling laws in terms of the total debris mass and explosion speed are derived and verified for the maximal size of the debris cloud and the fraction of debris that free-streams from the burst along the magnetic field. The amount of debris that escapes from the burst with minimal coupling to the background magnetic field increases with the debris gyroradius. Test cases with two different debris species--including a heavy minority species with a relatively large gyroradius--highlight how the collisionless coupling of the debris depends on the single-particle trajectories as well as the overall conservation of energy and momentum.