Current sheet formation under radiative cooling

TL;DR

This paper develops an analytical MHD model showing how radiative cooling influences current sheet formation and magnetic reconnection, revealing that cooling can accelerate collapse and increase reconnection rates in optically thin regimes.

Contribution

It introduces a modified radiatively-cooled Sweet-Parker model accounting for variable current sheet length, enhancing understanding of magnetic reconnection under radiative cooling.

Findings

Cooling accelerates X-point collapse.

Strong cooling can reverse current sheet elongation.

Reconnection rate exceeds classical Sweet-Parker rate.

Abstract

We present a simple, analytically solvable MHD model of current sheet formation through X-point collapse under optically thin radiative cooling. Our results show that cooling accelerates the collapse of the X-point along the inflows, but strong cooling can arrest or even reverse the current sheet elongation in the outflow direction. Hence, we detail a modification to the radiatively-cooled Sweet-Parker model developed by Uzdensky & McKinney (2011) to allow for varying current sheet length. The steady-state solution shows that when radiative cooling dominates compressional heating, the current sheet length is shorter than the system size, with an increased reconnection rate compared to the classical Sweet-Parker rate. The model and subsequent results lay out the groundwork for a more complete theoretical understanding of magnetic reconnection in regimes dominated by optically thin radiative cooling.