Multiple current sheet systems in the outer heliosphere: Energy release and turbulence

TL;DR

This study uses 3D hybrid simulations to explore how multiple current sheets in the outer heliosphere undergo reconnection and turbulence, impacting particle acceleration and transport.

Contribution

It demonstrates that reconnection among multiple current sheets can generate turbulence, influencing energetic particle behavior in the outer heliosphere.

Findings

Reconnection leads to turbulence through cascades.

Magnetic fluctuations show anisotropy with guide fields.

Pickup protons do not significantly alter the turbulence.

Abstract

In the outer heliosphere, beyond the solar wind termination shock, it is expected that the warped heliospheric current sheet forms a region of closely-packed, multiple, thin current sheets. Such a system may be subject to the ion-kinetic tearing instability, and hence generate magnetic islands and hot populations of ions associated with magnetic reconnection. Reconnection processes in this environment have important implications for local particle transport, and for particle acceleration at reconnection sites and in turbulence. We study this complex environment by means of three-dimensional hybrid simulations over long time scales, in order to capture the evolution from linear growth of the tearing instability to a fully developed turbulent state at late times. The final state develops from the highly ordered initial state via both forward and inverse cascades. Component and spectral anisotropy in the magnetic fluctuations is present when a guide field is included. The inclusion of a population of new-born interstellar pickup protons does not strongly affect these results. Finally, we conclude that reconnection between multiple current sheets can act as an important source of turbulence in the outer heliosphere, with implications for energetic particle acceleration and propagation.