Self-similar solutions of oscillatory reconnection: parameter study of magnetic field strength and background temperature

TL;DR

This study explores self-similar oscillatory reconnection solutions in low-beta plasmas by analyzing the effects of magnetic field strength and temperature, unifying previous findings through a parametric energy ratio approach.

Contribution

It introduces a parameter space based on energy ratios, revealing self-similar solutions and unifying diverse previous studies of oscillatory reconnection.

Findings

Self-similar oscillations occur in low-beta plasma environments.

Oscillation characteristics depend on the internal-to-magnetic energy ratio.

The study unifies various previous observations under a common framework.

Abstract

Oscillatory reconnection is a specific type of time-dependent reconnection which involves periodic changes in the magnetic topology of a null point. The mechanism has been reported for a variety of magnetic field strengths and configurations, background temperatures and densities. All these studies report an oscillation in the current density at the null point, but also report a variety of periods, amplitudes and overall behaviors. We conduct a parametric study for equilibrium magnetic field strength and initial background temperature, solving 2D resistive MHD equations around a magnetic X-point. We introduce a parameter space for the ratio of internal-to-magnetic energy and find self-similar solutions for simulations where this ratio is below 0.1 (which represents a magnetically-dominated environment or, equivalently, a low-beta plasma). Self-similarity can be seen in oscillations in the current density at the null (including amplitude and period), Ohmic heating and the temperature generated via reconnection jets. The parameter space of energy ratios also allows us to contextualize previous studies of the oscillatory reconnection mechanism and bring those different studies together into a single unified understanding.