Synchrotron Magnetic Fields from Rayleigh-Taylor Instability in Supernovae

TL;DR

This paper investigates how Rayleigh-Taylor instability in supernovae can generate and amplify magnetic fields, finding a minimum magnetic energy fraction of 0.3% of equipartition, crucial for understanding supernova synchrotron emission.

Contribution

The study provides the first high-resolution simulations linking Rayleigh-Taylor turbulence to magnetic field amplification in supernovae, establishing a minimum magnetic energy fraction.

Findings

Magnetic fields can reach at least 0.3% of equipartition energy.

Rayleigh-Taylor instability-driven turbulence amplifies magnetic fields near the reverse shock.

A minimum magnetic energy fraction of 0.003 is suggested for all interacting supernovae.

Abstract

Synchrotron emission from a supernova necessitates a magnetic field, but it is unknown how strong the relevant magnetic fields are, and what mechanism generates them. In this study, we perform high-resolution numerical gas dynamics calculations to determine the growth of turbulence due to Rayleigh-Taylor instability, and the resulting kinetic energy in turbulent fluctuations, to infer the strength of magnetic fields amplified by this turbulence. We find that Rayleigh-Taylor instability can produce turbulent fluctuations strong enough to amplify magnetic fields to a few percent of equipartition with the thermal energy. This turbulence stays concentrated near the reverse shock, but averaging this magnetic energy throughout the shocked region (weighting by emissivity) sets the magnetic fields at a minimum of 0.3 percent of equipartition. This suggests a minimum effective magnetic field strength ($\epsilon_B > 0.003$) which should be present in all interacting supernovae.