2026/06/29 by Keitarou Matsumoto, Satoshi Inoue, Meiqi Wang +6
Earth and Planetary Sciences · Physics and Astronomy · #Earthquake Detection and Analysis #Ionosphere and magnetosphere dynamics #Solar and Space Plasma Dynamics #astro-ph.SR
paper · pdf · doi:10.3847/1538-4357/ae84b8
It has been accepted by ApJ
arxiv created 2026/06/29 · openalex publication_date 2026/07/30 · arxiv updated 2026/07/31 · openalex created_date 2026/07/31 · openalex updated_date 2026/07/31
Abstract We analyze the X7.1 flare on 2024 October 1 from NOAA AR 13842 using hard X-ray (HXR) imaging, microwave observations by the Expanded Owens Valley Solar Array (EOVSA), and a three-dimensional magnetohydrodynamic (MHD) simulation. The flare was observed from two vantage points, with Solar Orbiter/Spectrometer Telescope for Imaging X-rays viewing the flare near the limb and Advanced Space-based Solar Observatory/Hard X-ray Imager and EOVSA observing it on the disk. We carried out a data-constrained MHD simulation using a nonlinear force-free field extrapolation as the initial condition and constrained the height of the nonthermal loop-top source from stereoscopic HXR and microwave observations. The height is consistent between the stereoscopic analysis and the MHD simulation. A secondary nonthermal microwave source aligned with a southward plasma ejection corresponds to an elongated current sheet. Although the current sheet grows in multiple directions, the secondary microwave emission is observed only from the southern segment. This localization suggests reconnection in regions with different magnetic field strengths. Reconnection in strong-field regions produces flare arcades with dominant loop-top emission, whereas reconnection in weaker southern regions gives rise to secondary microwave emission at higher altitudes. The height of the secondary source is consistent between the stereoscopic analysis and the MHD simulation. Microwave spectral fitting suggests a higher low-energy cutoff for nonthermal electrons in the secondary microwave source than in the main loop-top source. This may reflect the transport of electrons preaccelerated near the loop-top source by the southward plasma ejection.