Multifluid magnetohydrodynamic turbulence in weakly ionised astrophysical plasmas

TL;DR

This paper presents initial simulations of multifluid MHD turbulence in molecular clouds, showing that multifluid effects significantly alter turbulence properties at sub-parsec scales, challenging ideal MHD assumptions.

Contribution

First simulation study of 4-fluid MHD turbulence in molecular clouds highlighting the impact of multifluid effects on turbulence properties.

Findings

Power spectra of velocity and magnetic fields are softened.

Density PDFs of charged and neutral fluids differ significantly.

Magnetic field shows less spatial structure than in ideal MHD.

Abstract

Initial results from simulations of 4-fluid MHD turbulence in molecular clouds are presented. The species included in the simulations are ions, electrons, negatively charged dust grains and neutrals. The results indicate that, on length scales of a few tenths of a parsec, multifluid effects have a significant impact on the properties of the turbulence. In particular, the power spectra of the velocity and magnetic fields are significantly softened, while the PDF of the densities of the charged and neutral fluids are appreciably different. Indeed, the magnetic field strength displays much less spatial structure on all lengthscales up to 1 pc than in the ideal MHD case. The assumptions of ideal MHD therefore appear to be inadequate for simulating turbulence in molecular clouds at these length scales.