Switchbacks in the near-Sun magnetic field: long memory and impact on the turbulence cascade

TL;DR

This study analyzes the properties of magnetic switchbacks observed by Parker Solar Probe, revealing their self-similar nature, long memory effects, and their influence on turbulence, with implications for understanding the pristine solar wind.

Contribution

It provides the first detailed analysis of the macroscopic properties of switchbacks, highlighting their self-similarity, long memory, and impact on turbulence spectra, which was not previously characterized.

Findings

Switchbacks are self-similar with no characteristic size or duration.

Their occurrence rate exhibits long memory and aggregation.

Turbulence spectra differ inside and outside switchbacks, indicating different fluctuation regimes.

Abstract

One of the most striking observations made by Parker Solar Probe during its first solar encounter is the omnipresence of rapid polarity reversals in a magnetic field that is otherwise mostly radial. These so-called switchbacks strongly affect the dynamics of the magnetic field. We concentrate here on their macroscopic properties. First, we find that these structures are self-similar, and have neither a characteristic magnitude, nor a characteristic duration. Their waiting time statistics shows evidence for aggregation. The associated long memory resides in their occurrence rate, and is not inherent to the background fluctuations. Interestingly, the spectral properties of inertial range turbulence differ inside and outside of switchback structures; in the latter the $1/f$ range extends to higher frequencies. These results suggest that outside of these structures we are in the presence of lower amplitude fluctuations with a shorter turbulent inertial range. We conjecture that these correspond to a pristine solar wind.