Quasi-periodic pulsations and three-dimensional magnetic reconnection during 2022 March 31 flare observed by IRIS & STIX

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Hauptverfasser: Lorincik, Juraj, Collier, Hannah, Polito, Vanessa, Hayes, Laura A., Ashfield IV, William H., Freij, Nabil
Format: Preprint
Veröffentlicht: 2026
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author Lorincik, Juraj
Collier, Hannah
Polito, Vanessa
Hayes, Laura A.
Ashfield IV, William H.
Freij, Nabil
author_facet Lorincik, Juraj
Collier, Hannah
Polito, Vanessa
Hayes, Laura A.
Ashfield IV, William H.
Freij, Nabil
contents Apparent slipping motions of flare ribbon kernels and the formation of hard X-ray (HXR) footpoints are important signatures of magnetic reconnection in solar flares. Ultraviolet (UV) and HXR ribbon emission can show quasi-periodic pulsations (QPPs), but the link between HXR QPP sources and slipping reconnection remains poorly understood. In this work, we analyze high-cadence IRIS and STIX observations of the 2022 March 31 M9.6 flare. STIX detected non-thermal QPPs with periods of $\approx$35 s from two relatively stationary footpoints. The majority of the HXR QPPs were correlated with UV pulsations observed by the IRIS Slit Jaw Imager in ribbon regions encompassing these footpoints. In one such region observed under the IRIS slit, the Si IV 1402.77Å line exhibited pulsations in intensity, Doppler shift, and width, some of which were coincident with HXR QPPs. Apparent slipping motions of the UV kernels were also observed, but their locations, timing, and UV intensity variability showed lower correlation with the HXR QPPs. The ribbons along which the slipping kernels were found correspond well to footprints of quasi-separatrix layers (QSLs), regions of high magnetic connectivity gradients, identified using a NLFFF extrapolation. Our multi-instrument analysis suggests that strong deposition of energy by non-thermal electrons was concentrated in a specific loop system within a large-scale 3D reconnection structure. Slipping kernels were subjected to weaker, if any, energization by non-thermal electrons, offering new constraints on 3D reconnection and flare energy release.
format Preprint
id arxiv_https___arxiv_org_abs_2604_17330
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Quasi-periodic pulsations and three-dimensional magnetic reconnection during 2022 March 31 flare observed by IRIS & STIX
Lorincik, Juraj
Collier, Hannah
Polito, Vanessa
Hayes, Laura A.
Ashfield IV, William H.
Freij, Nabil
Solar and Stellar Astrophysics
Apparent slipping motions of flare ribbon kernels and the formation of hard X-ray (HXR) footpoints are important signatures of magnetic reconnection in solar flares. Ultraviolet (UV) and HXR ribbon emission can show quasi-periodic pulsations (QPPs), but the link between HXR QPP sources and slipping reconnection remains poorly understood. In this work, we analyze high-cadence IRIS and STIX observations of the 2022 March 31 M9.6 flare. STIX detected non-thermal QPPs with periods of $\approx$35 s from two relatively stationary footpoints. The majority of the HXR QPPs were correlated with UV pulsations observed by the IRIS Slit Jaw Imager in ribbon regions encompassing these footpoints. In one such region observed under the IRIS slit, the Si IV 1402.77Å line exhibited pulsations in intensity, Doppler shift, and width, some of which were coincident with HXR QPPs. Apparent slipping motions of the UV kernels were also observed, but their locations, timing, and UV intensity variability showed lower correlation with the HXR QPPs. The ribbons along which the slipping kernels were found correspond well to footprints of quasi-separatrix layers (QSLs), regions of high magnetic connectivity gradients, identified using a NLFFF extrapolation. Our multi-instrument analysis suggests that strong deposition of energy by non-thermal electrons was concentrated in a specific loop system within a large-scale 3D reconnection structure. Slipping kernels were subjected to weaker, if any, energization by non-thermal electrons, offering new constraints on 3D reconnection and flare energy release.
title Quasi-periodic pulsations and three-dimensional magnetic reconnection during 2022 March 31 flare observed by IRIS & STIX
topic Solar and Stellar Astrophysics
url https://arxiv.org/abs/2604.17330