The effects of resistivity on oscillatory reconnection and consequences for solar flare Quasi Periodic Pulsations

TL;DR

This study uses 2D MHD simulations to explore how resistivity affects magnetic reconnection dynamics and oscillations, providing insights into the mechanisms behind solar flare QPPs.

Contribution

It demonstrates the significant impact of resistivity profiles on reconnection rate oscillations and radiation, advancing understanding of flare energy release processes.

Findings

Resistivity controls reconnection rate oscillations.

Resistivity influences gyrosynchrotron radiation oscillations.

Wave frequencies are nearly independent of resistivity variations.

Abstract

Quasi-periodic pulsations (QPPs) are often observed in flare emissions. While these may reveal much about the time-dependent reconnection involved in flare energy release, the underlying mechanisms are still poorly understood. In this paper, we use 2D magnetohydrodynamic simulations to investigate the magnetic reconnection in two merging flux ropes, focusing on the effects of the resistivity on the time variation of the reconnection. We consider both uniform resistivity and current-dependent anomalous resistivity profiles. Our findings reveal that resistivity plays a critical role in controlling the reconnection dynamics, including reconnection rate oscillations and the rate of decay of the reconnection rate. Resistivity also influences the oscillations in emitted gyrosynchrotron radiation. However, in contrast to this strong influence of resistivity on reconnection rates, we observed a different behaviour for the emitted waves, whose frequencies are almost independent of resistivity variations.