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arXiv · 2606.10506

Phase-drifting with emitting plasma temperature in the quasi-periodic pulsations of an X-class solar flare

Libo Fu·Valery M. Nakariakov·Ding Yuan·Suraj Sahu·Song Feng·Ehsan Tavabi
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Abstract

Recent multi-wavelength observations of solar flares have provided new constraints on the physical origin of quasi-periodic pulsations (QPPs). In an X-class flare, we detect a short-lived $\sim$5-minute QPP simultaneously in hard X-rays, extreme-ultraviolet (EUV), and soft X-ray emissions, exhibiting a clear phase-drifting behavior with emitting plasma temperature. Based on phase-resolved timing analysis, it is found that (i) the QPPs in all diagnostics share nearly identical oscillation periods, (ii) a systematic temperature-dependent phase drifting is present, with the phase delay relative to the hard X-ray emission increases systematically from the hottest to cooler EUV channels, and (iii) the QPP persists for only a few cycles during the impulsive phase. These properties imply that periodic magnetic reconnection, possibly triggered by the leakage of 5-minute oscillations from the lower atmosphere, modulates the non-thermal electrons responsible for the leading Hard X-ray QPPs. Subsequently, plasma heating and cooling processes manifest sequentially across passbands with different temperature responses, resulting in the observed temperature-dependent phase drifting. These results provide novel observational evidence supporting the use of multi-temperature, multi-wavelength phase relationships to constrain the temporal evolution of flare energy release and the origins of QPPs.

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Libo Fu, Valery M. Nakariakov, Ding Yuan, Suraj Sahu, Song Feng, Ehsan Tavabi. 2026-06-09. Phase-drifting with emitting plasma temperature in the quasi-periodic pulsations of an X-class solar flare. https://arxiv.org/abs/2606.10506

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