Oscillatory reconnection and waves driven by merging magnetic flux ropes in solar flares

Abstract

Oscillatory reconnection is a process that has been suggested to underlie several solar and stellar phenomena, and is likely to play an important role in transient events such as flares. Quasi-periodic pulsations (QPPs) in flare emissions may be a manifestation of oscillatory reconnection, but the underlying mechanisms remain uncertain. In this paper, we present 2D magnetohydrodynamic (MHD) simulations of two current-carrying magnetic flux ropes with an out-of-plane magnetic field undergoing oscillatory reconnection in which the two flux ropes merge into a single flux rope. We find that oscillatory reconnection can occur intrinsically without an external oscillatory driver during flux rope coalescence, which may occur both during large-scale coronal loop interactions and the merging of plasmoids in fragmented current sheets. Furthermore, we demonstrate that radially propagating non-linear waves are produced in the aftermath of flux rope coalescence, due to the post-reconnection oscillations of the merged flux rope. The behaviour of these waves is found to be almost independent of the initial out-of-plane magnetic field. It is estimated that the waves emitted through merging coronal loops and merging plasmoids in loop-top current sheets would have a typical phase speed of 90 km/s and 900 km/s respectively. It is possible that the properties of the waves emitted during flux rope coalescence could be used as a diagnostic tool to determine physical parameters within a coalescing region.

17 pages, 7 figures, paper accepted by MNRAS 2022 May 04

References in corpus (26)

• Instability of current sheets and formation of plasmoid chains
• Observing the Roots of Solar Coronal Heating - in the Chromosphere
• Coronal heating by MHD waves
• The first observed stellar X-ray flare oscillation: Constraints on the flare loop length and the magnetic field
• Slow-Mode Magnetoacoustic Waves in Coronal Loops
• A large-scale search for evidence of quasi-periodic pulsations in solar flares
• Three-dimensional oscillatory magnetic reconnection
• On the Value of the Reconnection Rate
• Superflares on solar-type stars from the first year observation of TESS
• Particle acceleration and transport in reconnecting twisted loops in a stratified atmosphere
• STEREO Observations of Quasi-Periodically Driven High Velocity Outflows in Polar Plumes
• Generation of quasi-periodic waves and flows in the solar atmosphere by oscillatory reconnection
• The periodic variations of a white-light flare observed with ULTRACAM
• A fully self-consistent model for solar flares
• A blueprint of state-of-the-art techniques for detecting quasi-periodic pulsations in solar and stellar flares
• Fractal Reconnection in Solar and Stellar Environments
• Flux rope merging and the structure of switchbacks in the solar wind
• Oscillatory Reconnection of a 2D X-point in a hot coronal plasma
• Coronal heating in multiple magnetic threads
• Forced magnetic reconnection and plasmoid coalescence: I - MHD Simulations
• Degree of electric current neutralization and the activity in solar Active Regions
• Observational Signatures of Tearing Instability in the Current Sheet of a Solar Flare
• Magnetic reconnection between loops accelerated by a nearby filament eruption
• Eruption of EUV Hot-Channel near Solar Limb and Associated Moving Type-IV Radio Burst
• An evaluation of possible mechanisms for anomalous resistivity in the solar corona
• Pulsations of microwave emission from a solar flare in a twisted loop caused by intrinsic MHD oscillations

Cited by in corpus (6)

• Oscillatory reconnection as a plasma diagnostic in the solar corona
• Particle acceleration and their escape into the heliosphere in solar flares with open magnetic field
• The effects of resistivity on oscillatory reconnection and consequences for solar flare Quasi Periodic Pulsations
• Self-similar solutions of oscillatory reconnection: parameter study of magnetic field strength and background temperature
• The periodicity of three-dimensional oscillatory reconnection
• The independence of oscillatory reconnection periodicity from the initial pulse