Asymmetric Magnetic Reconnection in Weakly Ionized Chromospheric Plasmas

Abstract

Realistic models of magnetic reconnection in the solar chromosphere must take into account that the plasma is partially ionized and that plasma conditions within any two magnetic flux bundles undergoing reconnection may not be the same. Asymmetric reconnection in the chromosphere may occur when newly emerged flux interacts with pre-existing, overlying flux. We present 2.5D simulations of asymmetric reconnection in weakly ionized, reacting plasmas where the magnetic field strengths, ion and neutral densities, and temperatures are different in each upstream region. The plasma and neutral components are evolved separately to allow non-equilibrium ionization. As in previous simulations of chromospheric reconnection, the current sheet thins to the scale of the neutral-ion mean free path and the ion and neutral outflows are strongly coupled. However, the ion and neutral inflows are asymmetrically decoupled. In cases with magnetic asymmetry, a net flow of neutrals through the current sheet from the weak field (high density) upstream region into the strong field upstream region results from a neutral pressure gradient. Consequently, neutrals dragged along with the outflow are more likely to originate from the weak field region. The Hall effect leads to the development of a characteristic quadrupole magnetic field modified by asymmetry, but the X-point geometry expected during Hall reconnection does not occur. All simulations show the development of plasmoids after an initial laminar phase.

Accepted for publication in the Astrophysical Journal

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• Heating mechanisms in the low solar atmosphere through magnetic reconnection in current sheets
• Magnetic reconnection in strongly magnetized regions of the low solar chromosphere
• On the effects of ion-neutral interactions in solar plasmas
• A Magnetic Reconnection model for Hot Explosions in the Cool Atmosphere of the Sun
• Two-fluid Modeling of Acoustic Wave Propagation in Gravitationally Stratified Isothermal Media
• Coalescence Instability in Chromospheric Partially Ionised Plasmas
• Plausibility of ultraviolet burst generation in the low solar chromosphere
• Collisional ionisation and recombination effects on coalescence instability in chromospheric partially ionised plasmas
• Extreme-ultraviolet (EUV) observables of simulated plasmoid-mediated reconnection in the solar corona
• Spatial Offsets in Flare-CME Current Sheets