Understanding the Physical Nature of Coronal "EIT Waves"

TL;DR

This paper reviews the long-standing debate on the nature of 'EIT waves' in the solar corona, providing evidence that they are best described as fast-mode waves or shocks driven by coronal mass ejections.

Contribution

The study reexamines existing theories of 'EIT waves' using new observational data, supporting the interpretation of these phenomena as fast-mode waves or shocks.

Findings

'EIT waves' are consistent with fast-mode large-amplitude waves or shocks.

They are driven by impulsive expansion of coronal mass ejections.

Observational data from multiple spacecraft support the wave interpretation.

Abstract

For almost 20 years the physical nature of globally propagating waves in the solar corona (commonly called "EIT waves") has been controversial and subject to debate. Additional theories have been proposed over the years to explain observations that did not fit with the originally proposed fast-mode wave interpretation. However, the incompatibility of observations made using the Extreme-ultraviolet Imaging Telescope (EIT) onboard the Solar and Heliospheric Observatory with the fast-mode wave interpretation was challenged by differing viewpoints from the twin Solar Terrestrial Relations Observatory spacecraft and higher spatial/temporal resolution data from the Solar Dynamics Observatory. In this article, we reexamine the theories proposed to explain "EIT waves" to identify measurable properties and behaviours that can be compared to current and future observations. Most of us conclude that "EIT waves" are best described as fast-mode large-amplitude waves/shocks that are initially driven by the impulsive expansion of an erupting coronal mass ejection in the low corona.