Dynamics of the coronal magnetic field in the 2022-10-02 X-class flare

TL;DR

This study analyzes the magnetic field evolution during the 2022-10-02 X-class solar flare, revealing significant decay in the coronal magnetic field and its correlation with electron acceleration, using microwave data and 3D modeling.

Contribution

It provides new observational evidence of magnetic field decay during a disk solar flare and compares microwave-based measurements with 3D magnetic models.

Findings

Coronal magnetic field decays at up to 10 G s$^{-1}$ during the flare.

Magnetic field measurements are confirmed at loop legs and filament bottom.

Magnetic energy released is sufficient to power the flare components.

Abstract

Solar flares are driven by release of free magnetic energy and often associated with restructurization of the magnetic field topology. Yet, observations of evolving magnetic field in the flaring volume are limited to very few cases including the 2017-09-10 X8.2 limb flare; thus, a verification of whether a similar evolution takes place in other solar flares is needed. Here we report one more, 2022-10-02, X1.1 class solar flare but seen on disk, whose microwave data permit mapping the magnetic field over the flaring source and tracking magnetic field evolution over the course of the flare. We found that the coronal magnetic field shows a prominent decay with the rate up to 10 G s$^{-1}$ in several (above) loop-top locations. The magnetic field is also confidently measured at the loop legs and the bottom part of the erupting filament. Prominent acceleration of electrons is detected where the magnetic field decays. We developed 3D models of the flare, whose magnetic field shows resemblance and also deviation from the magnetic field inferred from the microwave data. This study confirms that the coronal magnetic field decays during the rise phase of the solar flare. The amount of released magnetic energy is sufficient to support other components of the flare energy.