Electron Landau Damping of Kinetic Alfv\'en Waves in Simulated Magnetosheath Turbulence

TL;DR

This study uses high-resolution gyrokinetic simulations to investigate electron Landau damping's role in turbulence dissipation in the Earth's magnetosheath, aligning with recent MMS observations and advancing understanding of plasma heating mechanisms.

Contribution

It provides the first detailed numerical simulation analysis of electron Landau damping in kinetic Alfvén wave turbulence within the magnetosheath, complementing observational data.

Findings

Qualitative agreement with MMS observations on electron energization

Identification of field-particle interaction signatures of Landau damping

Insights into the effects of dispersive kinetic Alfvén waves on energy dissipation

Abstract

Turbulence is thought to play a role in the heating of the solar wind plasma, though many questions remain to be solved regarding the exact nature of the mechanisms driving this process in the heliosphere. In particular, the physics of the collisionless interactions between particles and turbulent electromagnetic fields in the kinetic dissipation range of the turbulent cascade remains incompletely understood. A recent analysis of an interval of Magnetosphere Multiscale (MMS) observations has used the field-particle correlation technique to demonstrate that electron Landau damping is involved in the dissipation of turbulence in the Earth's magnetosheath. Motivated by this discovery, we perform a high-resolution gyrokinetic numerical simulation of the turbulence in the MMS interval to investigate the role of electron Landau damping in the dissipation of turbulent energy. We employ the field-particle correlation technique on our simulation data, compare our results to the known velocity-space signatures of Landau damping outside the dissipation range, and evaluate the net electron energization. We find qualitative agreement between the numerical and observational results for some key aspects of the energization and speculate on the nature of disagreements in light of experimental factors, such as differences in resolution, and of developing insights into the nature of field-particle interactions in the presence of dispersive kinetic Alfv\'en waves.