Microwave response to kink oscillations of a plasma slab

Abstract

The modulation of the intensity of microwave emission from a plasma slab caused by a standing linear kink fast magnetoacoustic wave is considered. The slab is stretched along a straight magnetic field, and can represent, for example, a current sheet in a flaring active region in corona of the Sun, or a streamer or pseudostreamer stalk. The plasma density is non-uniform in the perpendicular direction and described by a symmetric Epstein profile. The plasma parameter $\beta$ is taken to be zero, which is a good approximation for solar coronal active regions. The microwave emission is caused by mildly relativistic electrons which occupy a layer within the oscillating slab and radiate via the gyrosynchrotron (GS) mechanism. Light curves of the microwave emission were simulated in the optically thin part of the GS spectrum, and their typical Fourier spectra were analysed. It is shown that the microwave response to a linear kink magnetohydrodynamic wave is non-linear. It is found that, while the microwave light curves at the node oscillate with the same frequency as the frequency of the perturbing kink mode, the frequency of the microwave oscillations at the anti-node is two times higher than the kink oscillation frequency. Gradual transformation the one type of the light curves to another occurs when sliding from the node to the anti-node. This result does not depend on the width of the GS-emitting layer inside the oscillating slab. This finding should be considered in the interpretation of microwave quasi-periodic pulsations in solar and stellar flares.

References in corpus (12)

• Persistent Doppler shift oscillations observed with HINODE/EIS in the solar corona: spectroscopic signatures of Alfvenic waves and recurring upflows
• Kink oscillations of coronal loops
• What drives decayless kink oscillations in active region coronal loops on the Sun?
• Flare induced decay-less transverse oscillations in solar coronal loops
• Two-Spacecraft Detection of Short-period Decayless Kink Oscillations of Solar Coronal Loops
• Fast magnetoacoustic wave trains: from tadpoles to boomerangs
• Motion magnification in coronal seismology
• Multiple Regions of Nonthermal Quasi-Periodic Pulsations during the Impulsive Phase of a Solar Flare
• Impulsively Generated Kink Wave Trains in Solar Coronal Slabs
• Pulsations of microwave emission from a solar flare in a twisted loop caused by intrinsic MHD oscillations
• Modulation of the solar microwave emission by sausage oscillations
• Influence of fine structures on gyrosynchrotron emission of flare loops modulated by sausage modes

Cited by in corpus (1)

• Traveling kink oscillations of coronal loops launched by a solar flare