Simulations of Electron Magnetohydrodynamic Turbulence

TL;DR

This paper presents numerical simulations of EMHD and ERMHD turbulence, revealing similar spectral properties, anisotropy scaling, and statistical behaviors, with implications for astrophysical phenomena like solar wind and magnetic reconnection.

Contribution

It introduces new techniques to analyze anisotropy in EMHD turbulence and compares the statistical properties of EMHD and MHD turbulence, highlighting key differences in their bispectra.

Findings

EMHD and ERMHD turbulence exhibit similar spectra and anisotropy.

High-order statistics follow She-Leveque scaling.

Bispectra differ significantly between EMHD and MHD turbulence.

Abstract

We present numerical simulations of electron magnetohydrodynamic (EMHD) and electron reduced MHD (ERMHD) turbulence. Comparing scaling relations, we find that both EMHD and ERMHD turbulence show similar spectra and anisotropy. We develop new techniques to study anisotropy of EMHD turbulence. Our detailed study of anisotropy of EMHD turbulence supports our earlier result of k_par ~ k_perp^(1/3) scaling. We find that the high-order statistics show a scaling that is similar to the She-Leveque scaling. We observe that the bispectra, which characterize the interaction of different scales within the turbulence cascade, are very different for EMHD and MHD turbulence. We show that both decaying and driven EMHD turbulence have the same statistical properties. We calculate the probability distribution functions (PDFs) of MHD and EMHD turbulence and compare them with those of interplanetary turbulence. We find that, as in the case of the solar wind, the PDFs of the increments of magnetic field strength in MHD and EMHD turbulence are well described by the Tsallis distribution. We discuss implications of our results for astrophysical situations, including the ADAFs and magnetic reconnection.