Mechanisms responsible for quasi-periodic pulsations in solar-flare hard-X-ray light curves

Determine the physical mechanisms responsible for quasi-periodic pulsations in solar-flare hard-X-ray light curves, including the possible roles of magnetohydrodynamic-wave modulation, modulation of energy-release efficiency, and spontaneous quasi-periodic energy release.

Background

The paper explains that hard-X-ray light curves from solar flares frequently exhibit quasi-periodic pulsations (QPPs), whose temporal signatures can be investigated using wavelet analysis, Automated Flare Inference of Oscillations (AFINO), and Gaussian decomposition. These tools identify candidate periodicities but do not resolve the physical origin of the pulsations.

The authors identify several possible explanations—direct modulation of the emission by magnetohydrodynamic waves, modulation of the efficiency of the energy-release process, and spontaneous quasi-periodic energy release—indicating that distinguishing among these mechanisms remains an unresolved problem in solar-flare physics.

References

The mechanisms responsible for QPPs are not yet well understood, but some possible explanations include direct modulation of emission caused by MHD waves, modulation of the efficiency of the energy release process and spontaneous quasi-periodic energy release.

— Comprehensive solar eruption analyses enabled by the tools of the SOLER project  (2608.24458 - Dresing et al., 25 Aug 2026) in Section 3.2.1, “X-ray timeseries analysis workflow”

However, the origin of QPPs is not yet fully understood and requires further investigation.

— Investigation of an X-class Flare and Quasi-Periodic Pulsations in NOAA AR 13842 using SDO, Aditya-L1 and Solar Orbiter  (2610.22165 - Kumara et al., 15 Oct 2026) in Section 1, Introduction

However, this interpretation remains speculative, as the present study does not include time-dependent MHD simulations capable of directly validating the proposed reconnection dynamics. The different QPP periods observed in the HXR, UV, and EUV wavebands may arise from the different physical responses of the solar atmosphere to repetitive energy release and particle acceleration during magnetic reconnection.

— Investigation of an X-class Flare and Quasi-Periodic Pulsations in NOAA AR 13842 using SDO, Aditya-L1 and Solar Orbiter  (2610.22165 - Kumara et al., 15 Oct 2026) in Section 4, Comparison of the extrapolated configuration with the observations; Section 5, Summary and Discussion