Interpreting Ulysses data using inverse scattering theory: Oblique Alfv\'en waves

TL;DR

This paper analyzes solitary wave structures observed by the Ulysses spacecraft in the solar wind, using inverse scattering theory and the DNLS equation, suggesting they are long-lived solitons potentially generated by plasma instabilities.

Contribution

It applies inverse scattering theory to space plasma data and demonstrates the consistency of observed structures with soliton solutions of the DNLS equation, a novel approach in this context.

Findings

Several structures match DNLS soliton solutions

Structures may be long-lived solitons in space plasma

Solitons could originate from plasma instabilities

Abstract

Solitary wave structures observed by the Ulysses spacecraft in the solar wind were analyzed using both inverse scattering theory as well as direct numerical integration of the derivative nonlinear Schr\"odinger (DNLS) equation. Several of these structures were found to be consistent with soliton solutions of the DNLS equation. Such solitary structures have been commonly observed in the space plasma environment and may, in fact, be long-lived solitons. While the generation of these solitons may be due to an instability mechanism, e.g., the mirror instability, they may be observable far from the source region due to their coherent nature.