Collaborative Research: The Role of Supra-arcade Downflows on Energy Transfer in Solar Flares

Solar flares are the most energetic phenomena in the solar system, during which the flare Above-the-Loop-Top (ALT) regions are the key to understanding energy release in solar flares. This project aims to obtain a more comprehensive picture of the energy release in flare ALT regions by systematically investigating the energy transfer associated with spatially resolved supra arcade downflows (SADs).

The improved knowledge of the energy transfer in solar flares is critical to understanding the basic science needed to meet the goals of the National Space Weather Strategy and Action Plan, which aims to develop tools to forecast space weather and mitigate its impacts. The project involves state-of-art MHD models, innovative particle simulations, and an image synthesis approach, to compare with observations in multiple wavelengths and viewing perspectives (including microwave imaging spectroscopy in fans that have been rarely studied in the community).

This project, led by several early-career women PIs, will involve undergraduate students and support a graduate student. There are outreach activities and developing open-source codes planned for this project.

Over the decades, the developments of 2D standard solar flare models have significantly improved the comprehension of solar eruptions. However, recent observations have indicated the importance of SADs, which are frequently observed from a face-on viewing perspective, to energy transfer in flare ALT regions. The project will thoroughly explore the role of SADs in energy transfer in the ALT regions by combining observations and simulations.

The science questions to be addressed are: (1) How do SADs engage in energy transfer in ALT regions? (2) What are the statistical features of plasma conditions around SADs? And (3) What are observational signatures related to energy transfer processes of SADs in ALT regions? First, they will perform a statistical study on the thermal characteristics and the physical relationship between these characteristics and the dynamics of SADs.

Second, they will perform 3D magnetohydrodynamics (MHD) simulations to investigate the energy release in flares. They will synthesize the emissions incorporating different viewing perspectives and multi-wavelengths to compare with observations, including radio emissions in fans that are rarely discussed in the literature. Third, they will carry out particle simulations with time-resolved dynamics provided by the MHD framework to explore the impact of SADs on energetic particles.

Combining the three steps above, they will comprehensively determine the role of SADs on energy transfer in flares and use the findings to improve the traditional scenario of energy release in flares.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.