Magnetic Field Amplification Associated with the Richtmyer-Meshkov Instability

TL;DR

This study uses 2D MHD simulations to show that the Richtmyer-Meshkov instability can significantly amplify magnetic fields, potentially explaining strong magnetic fields in astrophysical phenomena like supernova remnants.

Contribution

It demonstrates that RMI can amplify magnetic fields by over two orders of magnitude through fluid motions, providing a new mechanism for magnetic field enhancement in astrophysics.

Findings

Magnetic field is amplified by more than 100 times due to RMI.

Amplification is governed by a balance between magnetic and thermal pressures.

The process is effective across various shock Mach numbers and density ratios.

Abstract

The amplification of a magnetic field due to the Richtmyer-Meshkov instability (RMI) is investigated by two-dimensional MHD simulations. Single-mode analysis is adopted to reveal definite relation between the nonlinear evolution of RMI and the field enhancement. It is found that an ambient magnetic field is stretched by fluid motions associated with the RMI, and the strength is amplified significantly by more than two orders of magnitude. The saturation level of the field is determined by a balance between the amplified magnetic pressure and the thermal pressure after shock passage. This effective amplification can be achieved in a wide range of the conditions for the RMI such as the Mach number of an incident shock and the density ratio at a contact discontinuity. The results suggest that the RMI could be a robust mechanism of the amplification of interstellar magnetic fields and cause the origin of localized strong fields observed at the shock of supernova remnants.