Influence of fine structures on gyrosynchrotron emission of flare loops modulated by sausage modes

Abstract

Sausage modes are one leading mechanism for interpreting short period quasi-periodic pulsations (QPPs) of solar flares. Forward modeling their radio emission is crucial for identifying sausage modes observationally and for understanding their connections with QPPs. Using the numerical output from three-dimensional magnetohydrodynamic (MHD) simulations, we forward model the gyrosynchrotron (GS) emission of flare loops modulated by sausage modes and examine the influence of loop fine structures. The temporal evolution of the emission intensity is analyzed for an oblique line of sight crossing the loop center. We find that the low- and high-frequency intensities oscillate in-phase at the period of sausage modes for models with or without fine structures. For low-frequency emissions where the optically thick regime arises, the modulation magnitude of the intensity is dramatically reduced by the fine structures at some viewing angles. On the contrary, for high-frequency emissions where the optically thin regime holds, the effect of fine structures or viewing angle is marginal. Our results show that the periodic intensity variations of sausage modes are not wiped out by the fine structures, and sausage modes remains a promising candidate mechanism for QPPs even when flare loops are fine-structured.

arXiv commentAccepted for publication in ApJ Letters

References in corpus (20)

• Solar science with the Atacama Large Millimeter/submillimeter Array - A new view of our Sun
• Quasi-periodic pulsations in solar and stellar flares: an overview of recent results
• Structure of solar coronal loops: from miniature to large-scale
• Evidence for Widespread Cooling in an Active Region Observed with the SDO Atmospheric Imaging Assembly
• On active region loops: Hinode/EIS observations
• Global sausage oscillation of solar flare loops detected by the Interface Region Imaging Spectrograph
• Resonant absorption in complicated plasma configurations: applications to multi-stranded coronal loop oscillations
• Magnetohydrodynamic Fast Sausage Waves in the Solar Corona
• The Width Distribution of Loops and Strands in the Solar Corona -- Are we Hitting Rock Bottom ?
• Broadband Quasi-Periodic Radio and X-ray Pulsations in a Solar Flare
• Transverse oscillations of two coronal loops
• 3D simulations of gyrosynchrotron emission from mildly anisotropic nonuniform electron distributions in symmetric magnetic loops
• The instability and non-existence of multi-stranded loops, when driven by transverse waves
• Coronal fuzziness modelled with pulse-heated multistranded loop systems
• Transverse oscillations of a multi-stranded loop
• Observations of quasi-periodic solar X-ray emission as a result of MHD oscillations in a system of multiple flare loops
• Modeling of gyrosynchrotron radio emission pulsations produced by MHD loop oscillations in solar flares
• Wave heating in simulated multi-stranded coronal loops
• Simulations of Gyrosynchrotron Microwave Emission from an Oscillating 3D Magnetic Loop
• Fast Sausage Oscillations in Coronal Loops with Fine Structures

Cited by in corpus (4)

• 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
• On collective nature of nonlinear torsional Alfvén waves
• Modulation depth of the gyrosynchrotron emission as identifier of fundamental sausage modes