A violin sonata for reconnection

TL;DR

This paper introduces the topographical fluctuations analysis (TFA) to study electromagnetic and plasma fluctuations during magnetic reconnection, revealing two distinct fluctuation regimes with different characteristics.

Contribution

The study uncovers a new fluctuation regime near the reconnection inflow and separatrix regions, expanding understanding of magnetic reconnection dynamics.

Findings

Fluctuations in outflows are linked to plasma-electromagnetic interactions.

A new regime of electromagnetic fluctuations exists in the inflow and separatrix regions.

The analogy with violin bow vibrations illustrates the nature of electromagnetic fluctuations.

Abstract

The process of magnetic reconnection when studied in Nature or when modeled in 3D simulations differs in one key way from the standard 2D paradigmatic cartoon: it is accompanied by much fluctuations in the electromagnetic fields and plasma properties. We developed a new diagnostics, the topographical fluctuations analysis (TFA) to study the spectrum of fluctuations in the various regions around a reconnection site. We find that fluctuations belong to two very different regimes. The first regime is better known, it develops in the reconnection outflows and is characterized by a strong link between plasma and electromagnetic fluctuations leading to momentum and energy exchanges via anomalous viscosity and resistivity. But there is a second, new, regime: it develops in the inflow and in the region around the separatrix surfaces, including the reconnection diffusion region itself. In this new regime the plasma remains laminar but the electromagnetic fields fluctuates strongly. We present an analogy with the smooth continuous motion of the bow of a violin producing the vibrations of the strings to emit music.