Observations of quasi-periodic solar X-ray emission as a result of MHD oscillations in a system of multiple flare loops

Abstract

We investigate the solar flare of 20 October 2002. The flare was accompanied by quasi-periodic pulsations (QPP) of both thermal and nonthermal hard X-ray emissions (HXR) observed by RHESSI in the 3-50 keV energy range. Analysis of the HXR time profiles in different energy channels made with the Lomb periodogram indicates two statistically significant time periods of about 16 and 36 seconds. The 36-second QPP were observed only in the nonthermal HXR emission in the impulsive phase of the flare. The 16-second QPP were more pronounced in the thermal HXR emission and were observed both in the impulsive and in the decay phases of the flare. Imaging analysis of the flare region, the determined time periods of the QPP and the estimated physical parameters of magnetic loops in the flare region allow us to interpret the observations as follows. 1) In the impulsive phase energy was released and electrons were accelerated by successive acts with the average time period of about 36 seconds in different parts of two spatially separated, but interacting loop systems of the flare region. 2) The 36-second periodicity of energy release could be caused by the action of fast MHD oscillations in the loops connecting these flaring sites. 3) During the first explosive acts of energy release the MHD oscillations (most probably the sausage mode) with time period of 16 seconds were excited in one system of the flare loops. 4) These oscillations were maintained by the subsequent explosive acts of energy release in the impulsive phase and were completely damped in the decay phase of the flare.

14 pages, 4 figures

Cited by in corpus (18)

• Chromospheric Condensation and Quasi-periodic Pulsations in a Circular-ribbon Flare
• Quasi-Periodic Pulsations in Solar Flares: new clues from the Fermi Gamma-Ray Burst Monitor
• Line-of-sight geometrical and instrumental resolution effects on intensity perturbations by sausage modes
• Non-damping oscillations at flaring loops
• Doppler shift oscillations from a hot line observed by IRIS
• Quasi-periodic pulsations of gamma-ray emissions from a solar flare on 2017 September 06
• Spatio-temporal dynamics of sources of hard X-ray pulsations in solar flares
• Quasi-periodic pulsations with periods that change depending on whether the pulsations have thermal or nonthermal components
• Quasi-periodic pulsation detected in Lyman-alpha emission during solar flares
• Quasi-periodic pulsations with multiple periods in hard X-ray emission
• Instrumental oscillations in RHESSI count rates during solar flares
• Unveiling Spatiotemporal Properties of the Quasi-periodic Pulsations in the Balmer Continuum at 3600 Å in an X-class Solar White-light Flare
• Excitation of Multi-periodic Kink Motions in Solar Flare Loops: Possible Application to Quasi-periodic Pulsations
• Oscillations accompanying a He I 10830 Å negative flare in a solar facula
• Synthetic Extreme-ultraviolet Emissions Modulated by Leaky Fast Sausage Modes in Solar Active Region Loops
• Influence of fine structures on gyrosynchrotron emission of flare loops modulated by sausage modes
• The depth and the vertical extent of the energy deposition layer in a medium-class solar flare
• Quasi-Periodic Pulsations Detected in Ly$\alpha$ and Nonthermal Emissions During Solar Flares