Wave Decay in MHD Turbulence

TL;DR

This paper introduces a model for the nonlinear decay of weak waves in 3D incompressible MHD turbulence, highlighting directional differences and validating predictions through numerical simulations relevant to astrophysical phenomena.

Contribution

It provides a new general formula for wave decay in arbitrary directions and compares it with existing models, supported by numerical validation.

Findings

Decay rates differ for parallel and perpendicular waves

Numerical simulations confirm the model's predictions

Turbulent damping impacts astrophysical processes like linear instabilities

Abstract

We present a model for nonlinear decay of the weak wave in three-dimensional incompressible magnetohydrodynamic (MHD) turbulence. We show that the decay rate is different for parallel and perpendicular waves. We provide a general formula for arbitrarily directed waves and discuss particular limiting cases known in the literature. We test our predictions with direct numerical simulations of wave decay in three-dimensional MHD turbulence, and discuss the influence of turbulent damping on the development of linear instabilities in the interstellar medium and on other important astrophysical processes.