Three-dimensional mapping of coronal magnetic field and plasma parameters in a solar flare

¹ Institut für Sonnenphysik (KIS) Georges-Köhler-Allee 401 A D-79110 Freiburg, Germany
² Center For Solar-Terrestrial Research, New Jersey Institute of Technology Newark NJ 07102, USA
³ University College London, Mullard Space Science Laboratory Holmbury St Mary Dorking Surrey RH5 6NT, UK

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 1 October 2025
Accepted: 16 January 2026

Abstract

Aims. Diagnosing solar flare conditions is essential for understanding coronal energy release. Using combined microwave and X-ray data, we aim to reconstruct 3D maps of the magnetic fields and plasma parameters in the SOL2021-05-07 flare.

Methods. We used imaging spectroscopy from the Expanded Owens Valley Solar Array (EOVSA) to derive spatial maps of the magnetic field strength, as well as the thermal and nonthermal electron densities, along with the power-law index of nonthermal electrons via gyrosynchrotron modeling. Simultaneous X-ray observations from Hinode/X-Ray Telescope (Hinode/XRT) and Solar Orbiter/Spectrometer Telescope for Imaging X-rays (SolO/STIX), taken from different vantage points, enable a stereoscopic reconstruction of the flaring loop. By correlating the positions of microwave and thermal X-ray sources, we associated the 3D coordinates with the microwave-derived plasma parameters.

Results. We derived observational 3D maps of magnetic field strength, Alfvén speed, and plasma beta in a flaring volume, revealing a magnetically dominated environment. These spatially resolved diagnostics provide valuable constraints for models of magnetic reconnection and flare dynamics, representing a step toward a realistic 3D characterization of energy release in solar eruptive events.