Spectro-Polarimetric Properties of Sunquake Sources in X1.5 Flare and Evidence for Electron and Proton Beam Impacts

TL;DR

This study analyzes the spectro-polarimetric properties of sunquake sources during an X1.5 solar flare, revealing complex heating and magnetic field changes, and providing evidence for electron and proton beam impacts in the flare's impulsive phase.

Contribution

It offers a detailed spectro-polarimetric analysis of sunquake sources, highlighting complex physical processes beyond existing proton and electron beam models.

Findings

Rapid continuum emission variations coinciding with X-ray impulses

Transient emission in the line core indicating impulsive heating

Complex magnetic field changes in sunquake sources

Abstract

The first significant sunquake event of Solar Cycle 25 was observed during the X1.5 flare of May 10, 2022, by the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory. We perform a detailed spectro-polarimetric analysis of the sunquake photospheric sources, using the Stokes profiles of the FeI 6173A line, reconstructed from the HMI linear and circular polarized filtergrams. The results show fast variations of the continuum emission with rapid growth and slower decay lasting 3-4 min, coinciding in time with the hard X-ray impulses observed by the Konus instrument onboard the Wind spacecraft. The variations in the line core appeared slightly ahead of the variations in the line wings, showing that the heating started in the higher atmospheric layers and propagated downward. The most significant feature of the line profile variations is the transient emission in the line core in three of the four sources, indicating intense, impulsive heating in the lower chromosphere and photosphere. In addition, the observed variations of the Stokes profiles reflect transient and permanent changes in the magnetic field strength and geometry in the sunquake sources. Comparison with the radiative hydrodynamics models shows that the physical processes in the impulsive flare phase are substantially more complex than those predicted by proton and electron beam flare models currently presented in the literature.