Reflection of fast magnetosonic waves near magnetic reconnection region

Abstract

Magnetic reconnection in the solar corona is thought to be unstable to the formation of multiple interacting plasmoids, and previous studies have shown that plasmoid dynamics can trigger MHD waves of different modes propagating outward from the reconnection site. However, variations in plasma parameters and magnetic field strength in the vicinity of a coronal reconnection site may lead to wave reflection and mode conversion. In this paper we investigate the reflection and refraction of fast magnetoacoustic waves near a reconnection site. Under a justified assumption of an analytically specified Alfvén speed profile, we derive and solve analytically the full wave equation governing propagation of fast mode waves in a non-uniform background plasma without recourse to the small-wavelength approximation. We show that the waves undergo reflection near the reconnection current sheet due to the Alfvén speed gradient and that the reflection efficiently depends on the plasma-$\beta$ parameter as well as on the wave frequency. In particular, we find that waves are reflected more efficiently near reconnection sites in a low-$\beta$ plasma which is typical for the solar coronal conditions. Also, the reflection is larger for lower frequency waves while high frequency waves propagate outward from the reconnection region almost without the reflection. We discuss the implications of efficient wave reflection near magnetic reconnection sites in strongly magnetized coronal plasma for particle acceleration, and also the effect this might have on First Ionization Potential (FIP) fractionation by the ponderomotive force of these waves in the chromosphere.

28 pages, 10 figures, submitted to the Astrophysical Journal

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Cited by in corpus (5)

• Two-fluid simulations of waves in the solar chromosphere II. Propagation and damping of fast magneto-acoustic waves and shocks
• Three-dimensional MHD wave propagation near a coronal null point: a new wave mode decomposition approach
• Possible Detection of Subsecond-period Propagating Magnetohydrodynamics Waves in Post-reconnection Magnetic Loops during a Two-ribbon Solar Flare
• Element Abundances in Impulsive Solar Energetic Particle Events
• Giant overreflection of magnetohydrodynamic waves from inhomogeneous plasmas with nonuniform shear flows