Modulation of the solar microwave emission by sausage oscillations

Kupriyanova, E. G.; Kaltman, T. I.; Kuznetsov, A. A.

doi:10.1093/mnras/stac2386

Cited by 6 publications

(10 citation statements)

References 37 publications

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“…We assume that nonthermal electrons occupy a timevarying volume that initially corresponds to r 2 Mm (the yellow volume in Figure 1). This assumption is based on the consideration that nonthermal electrons determined by some acceleration mechanism may fill only part of the loop, similar to the model used in Kupriyanova et al (2022). This volume moves back and forth due to the kink motions.…”

Section: Methodsmentioning

confidence: 99%

“…This mechanism was shown to operate in the hot corona with the oscillatory periods independent of the initial velocity pulse (Karampelas et al 2022). Sausage modes can cause periodic compression and rarefaction and thus modulate the microwave emissions of flare loops (e.g., Mossessian & Fleishman 2012;Reznikova et al 2014;Kuznetsov et al 2015;Guo et al 2021;Shi et al 2022;Kupriyanova et al 2022). Candidate sausage modes have been reported in observations of QPPs in various passbands (e.g., Melnikov et al 2005;Zimovets & Struminsky 2010;Su et al 2012;Kolotkov et al 2015;Tian et al 2016; see the recent review by Li et al 2020).…”

Section: Introductionmentioning

confidence: 97%

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Excitation of Multiperiodic Kink Motions in Solar Flare Loops: Possible Application to Quasiperiodic Pulsations

Shi

Chen

et al. 2023

ApJL

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Magnetohydrodynamic (MHD) waves are often invoked to interpret quasiperiodic pulsations (QPPs) in solar flares. We study the response of a straight flare loop to a kink-like velocity perturbation using three-dimensional MHD simulations and forward model the microwave emissions using the fast gyrosynchrotron code. Kink motions with two periodicities are simultaneously generated, with the long-period component (P L = 57 s) being attributed to the radial fundamental kink mode and the short-period component (P S = 5.8 s) to the first leaky kink mode. Forward modeling results show that the two-periodic oscillations are detectable in the microwave intensities for some lines of sight. Increasing the beam size to (1″)2 does not wipe out the microwave oscillations. We propose that the first leaky kink mode is a promising candidate mechanism to account for short-period QPPs. Radio telescopes with high spatial resolutions can help distinguish between this new mechanism and such customary interpretations as sausage modes.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Excitation of Multiperiodic Kink Motions in Solar Flare Loops: Possible Application to Quasiperiodic Pulsations

Shi

Chen

et al. 2023

ApJL

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show abstract

“…We assume that non-thermal electrons occupy a time-varying volume that initially corresponds to r ≤ 2 Mm (the yellow volume in Figure 1). This assumption is based on the consideration that the non-thermal electrons determined by some acceleration mechanism may fill only part of the loop, similar to the model used in Kupriyanova et al (2022). This volume moves back and forth due to the kink motions.…”

Section: Methodsmentioning

confidence: 99%

“…This mechanism was shown to operate in the hot corona with the oscillatory periods independent of the initial velocity pulse (Karampelas et al 2022). Sausage modes can cause periodic compression and rarefaction and thus modulate the microwave emissions of flare loops (e.g., Mossessian & Fleishman 2012;Reznikova et al 2014;Kuznetsov et al 2015;Guo et al 2021;Kupriyanova et al 2022;Shi et al 2022). Candidate sausage modes have been reported in observations of QPPs in various passbands (e.g., Melnikov et al 2005;Zimovets & Struminsky 2010;Su et al 2012;Kolotkov et al 2015;Tian et al 2016; see the recent review by Li et al 2020).…”

Section: Introductionmentioning

confidence: 96%

Excitation of Multi-periodic Kink Motions in Solar Flare Loops: Possible Application to Quasi-periodic Pulsations

Shi¹,

Li²,

Chen³

et al. 2023

Preprint

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Magnetohydrodynamic (MHD) waves are often invoked to interpret quasi-periodic pulsations (QPPs) in solar flares. We study the response of a straight flare loop to a kink-like velocity perturbation using three-dimensional MHD simulations and forward model the microwave emissions using the fast gyrosynchrotron code. Kink motions with two periodicities are simultaneously generated, with the long-period component (P L = 57 s) being attributed to the radial fundamental kink mode and the short-period component (P S = 5.8 s) to the first leaky kink mode. Forward modeling results show that the two-periodic oscillations are detectable in the microwave intensities for some lines of sight. Increasing the beam size to (1 ) 2 does not wipe out the microwave oscillations. We propose that the first leaky kink mode is a promising candidate mechanism to account for short-period QPPs. Radio telescopes with high spatial resolutions can

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“…Moreover, in the optically thin regime, the kink wave causes the variation of the instantaneous column depth of the emitting segment of the waveguide. In the modelling of the modulation of the GS emission by an MHD wave, it also also necessary to take into account that the GS-emitting electrons do not necessarily occupy the whole oscillating volume (Kupriyanova et al 2022). Besides, filamentation of a coronal loop, caused by the development of the Kelvin-Helmholtz instability (e. g., Antolin & Van Doorsselaere 2019), could strongly affect the modulation depth of its microwave emission (Shi et al 2022).…”

Section: Introductionmentioning

confidence: 99%

Microwave response to kink oscillations of a plasma slab

Kaltman¹,

Kupriyanova²

2023

Preprint

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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 𝛽 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.

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Modulation of the solar microwave emission by sausage oscillations

Cited by 6 publications

References 37 publications

Excitation of Multiperiodic Kink Motions in Solar Flare Loops: Possible Application to Quasiperiodic Pulsations

Excitation of Multiperiodic Kink Motions in Solar Flare Loops: Possible Application to Quasiperiodic Pulsations

Excitation of Multi-periodic Kink Motions in Solar Flare Loops: Possible Application to Quasi-periodic Pulsations

Microwave response to kink oscillations of a plasma slab

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