Kinetic Simulations of Imbalanced Turbulence in a Relativistic Plasma: Net Flow and Particle Acceleration

TL;DR

This study uses 3D PIC simulations to explore how imbalanced turbulence in relativistic plasmas leads to net plasma flow and particle acceleration, with implications for astrophysical phenomena like accretion disk winds.

Contribution

It demonstrates that electromagnetic momentum converts into plasma momentum in imbalanced turbulence, causing significant net flow and particle acceleration in a relativistic plasma.

Findings

Net plasma flow speeds up to a significant fraction of lightspeed.

Particle acceleration produces a power-law energy distribution.

Imbalanced turbulence accelerates particles on a slower timescale than balanced turbulence.

Abstract

Turbulent high-energy astrophysical systems often feature asymmetric energy injection: for instance, Alfven waves propagating from an accretion disk into its corona. Such systems are "imbalanced": the energy fluxes parallel and anti-parallel to the large-scale magnetic field are unequal. In the past, numerical studies of imbalanced turbulence have focused on the magnetohydrodynamic regime. In the present study, we investigate externally-driven imbalanced turbulence in a collisionless, ultrarelativistically hot, magnetized pair plasma using three-dimensional particle-in-cell (PIC) simulations. We find that the injected electromagnetic momentum efficiently converts into plasma momentum, resulting in net motion along the background magnetic field with speeds up to a significant fraction of lightspeed. This discovery has important implications for the launching of accretion disk winds. We also find that although particle acceleration in imbalanced turbulence operates on a slower timescale than in balanced turbulence, it ultimately produces a power-law energy distribution similar to balanced turbulence. Our results have ramifications for black hole accretion disk coronae, winds, and jets.