Modelling the connection between propagating disturbances and solar spicules

TL;DR

This study uses 3D MHD simulations to model propagating disturbances in the solar atmosphere, linking them to spicule activity and wave dynamics, and demonstrating their role in coronal heating and solar wind acceleration.

Contribution

It presents a novel 3D MHD model showing PDs as slow magnetoacoustic pulses linked to wave steepening and shock formation, advancing understanding of their origin and impact.

Findings

PDs are consistent with slow magnetoacoustic pulses.

PDs carry energy flux capable of heating the lower corona.

Wave dynamics in the lower atmosphere generate observable PDs.

Abstract

Propagating (intensity) disturbances (PDs) are well reported in observations of coronal loops and polar plumes in addition to recent links with co-temporal spicule activity in the solar atmosphere. However, despite being reported in observations, they are yet to be studied in depth and understood from a modelling point of view. In this work, we present results from a 3D MHD numerical model featuring a stratified solar atmosphere which is perturbed by a p-mode wave driver at the photosphere, subsequently forming spicules described by the rebound shock model. Features with striking characteristics to those of detected PDs appear consistent with the co-temporal transition region dynamics and spicular activity resulting from nonlinear wave steepening and shock formation. Furthermore, the PDs can be interpreted as slow magnetoacoustic pulses propagating along the magnetic field, rather than high speed plasma upflows, carrying sufficient energy flux to at least partially heat the lower coronal plasma. Using forward modelling, we demonstrate the similarities between the PDs in the simulations and those reported in observations from IRIS and SDO/AIA. Our results suggest that, in the presented model, the dynamical movement of the transition region is a result of wave dynamics and shock formation in the lower solar atmosphere, and that PDs are launched co-temporally with the rising of the transition region, regardless of the wave-generating physical mechanisms occurring in the underlying lower solar atmosphere. However, it is clear that signatures of PDs appear much clearer when a photospheric wave driver is included. Finally, we present the importance of PDs in the context of providing a source for powering the (fast) solar wind