Detection of flare multi-periodic pulsations in mid-ultraviolet Balmer continuum, Ly-alpha, hard X-ray, and radio emissions simultaneously

TL;DR

This study investigates non-stationary quasi-periodic pulsations with multiple periods during a solar flare, observed across ultraviolet, X-ray, and radio wavelengths, revealing insights into flare dynamics and magnetic reconnection processes.

Contribution

It provides the first simultaneous detection of multi-periodic QPPs across multiple wavelengths during a solar flare, linking them to magnetic oscillations and energy release mechanisms.

Findings

Multiple periods (20-55 s) detected in Ly-alpha and UV emissions.

QPPs observed in hard X-ray and radio emissions.

Suggests magnetic reconnection and sausage oscillations as underlying mechanisms.

Abstract

Quasi-periodic pulsations (QPPs), which usually appear as temporal pulsations of the total flux, are frequently detected in the light curves of solar/stellar flares. In this study, we present the investigation of non-stationary QPPs with multiple periods during the impulsive phase of a powerful flare on 2017 September 06, which were simultane- ously measured by the Large-Yield RAdiometer (LYRA) and the Hard X-ray Modula- tion Telescope (Insight-HXMT), as well as the ground-based BLENSW. The multiple periods, detected by applying a wavelet transform and Lomb-Scargle periodogram to the detrended light curves, are found to be about 20-55 s in the Ly-alpha and mid-ultraviolet Balmer continuum emissions during the flare impulsive phase. Similar QPPs with multi- ple periods are also found in the hard X-ray emission and low-frequency radio emission. Our observations suggest that the flare QPPs could be related to nonthermal electrons accelerated by the repeated energy release process, i.e., triggering of repetitive magnetic reconnection, while the multiple periods might be modulated by the sausage oscillation of hot plasma loops. For the multi-periodic pulsations, other generation mechanisms could not be completely ruled out.