Distribution Functions of Sizes and Fluxes Determined from Supra-Arcade Downflows

TL;DR

This study analyzes the size and flux distributions of supra-arcade downflows, finding they follow log-normal or exponential patterns, which informs models of their formation process.

Contribution

It provides the first detailed statistical analysis of SAD sizes and fluxes, showing they follow specific non-power-law distributions, challenging previous assumptions.

Findings

Sizes are consistent with a log-normal distribution.

Fluxes are consistent with log-normal and exponential distributions.

Distributions are incompatible with power-law or normal models.

Abstract

The frequency distributions of sizes and fluxes of supra-arcade downflows (SADs) provide information about the process of their creation. For example, a fractal creation process may be expected to yield a power-law distribution of sizes and/or fluxes. We examine 120 cross-sectional areas and magnetic flux estimates found by Savage & McKenzie for SADs, and find that (1) the areas are consistent with a log-normal distribution and (2) the fluxes are consistent with both a log-normal and an exponential distribution. Neither set of measurements is compatible with a power-law distribution nor a normal distribution. As a demonstration of the applicability of these findings to improved understanding of reconnection, we consider a simple SAD growth scenario with minimal assumptions, capable of producing a log-normal distribution.