Three-Dimensional Simulations of Tearing and Intermittency in Coronal Jets

TL;DR

This paper uses high-resolution 3D simulations to explore how tearing instabilities cause fragmentation and intermittency in coronal jets, revealing flux rope formation and ejection as key processes.

Contribution

It demonstrates that tearing-like instabilities lead to flux rope formation and intermittent outflows in coronal jets, providing a detailed 3D simulation-based explanation.

Findings

Reconnection regions fragment into multiple null points and flux ropes.

Flux ropes are associated with density blobs and filamentary structures.

Repeated flux rope formation explains jet intermittency and bright blobs.

Abstract

Observations of coronal jets increasingly suggest that local fragmentation and intermittency play an important role in the dynamics of these events. In this work we investigate this fragmentation in high-resolution simulations of jets in the closed-field corona. We study two realizations of the embedded-bipole model, whereby impulsive helical outflows are driven by reconnection between twisted and untwisted field across the domed fan plane of a magnetic null. We find that the reconnection region fragments following the onset of a tearing-like instability, producing multiple magnetic null points and flux-rope structures within the current layer. The flux ropes formed within the weak-field region in the center of the current layer are associated with "blobs" of density enhancement that become filamentary threads as the flux ropes are ejected from the layer, whereupon new flux ropes form behind them. This repeated formation and ejection of flux ropes provides a natural explanation for the intermittent outflows, bright blobs of emission, and filamentary structure observed in some jets. Additional observational signatures of this process are discussed. Essentially all jet models invoke reconnection between regions of locally closed and locally open field as the jet-generation mechanism. Therefore, we suggest that this repeated tearing process should occur at the separatrix surface between the two flux systems in all jets. A schematic picture of tearing-mediated jet reconnection in three dimensions is outlined.