The scale-free texture of the fast solar wind

TL;DR

This study reveals a universal scale-free non-Gaussian behavior in magnetic field fluctuations of the fast solar wind across multiple time scales, indicating a single underlying stochastic process.

Contribution

It is the first to systematically quantify higher order statistics of magnetic field magnitude fluctuations in the solar wind across a wide range of scales.

Findings

Global non-Gaussian scale-free behavior from minutes to hours

Presence of an inertial range and a 1/f range in magnetic field data

Scale-dependent dynamic alignment of magnetic field and velocity components

Abstract

The higher order statistics of magnetic field magnitude fluctuations in the fast quiet solar wind are quantified systematically scale-by-scale for the first time. We find a single global non-Gaussian scale free behaviour from minutes to over 5 hours. This spans the signature of an inertial range of magnetohydrodynamic (MHD) turbulence and a ~1/f range in magnetic field components. This global scaling in field magnitude fluctuations is an intrinsic component of the underlying texture of the solar wind and it suggests a single stochastic process for magnetic field magnitude fluctuations operating across the full range of MHD time scales supported by the solar wind. Intriguingly, the magnetic field and velocity components show scale dependent dynamic alignment outside of the inertial range.