RHESSI Microflare Statistics II. X-ray Imaging, Spectroscopy & Energy Distributions

TL;DR

This study analyzes over 25,000 microflares observed by RHESSI, providing the first statistical insights into their thermal and non-thermal energy distributions through imaging and spectral analysis.

Contribution

It introduces a comprehensive automatic analysis method for microflares, combining imaging and spectral fitting to study their energy characteristics.

Findings

First statistical analysis of microflare thermal and non-thermal energies.

Quantitative relationships between microflare parameters.

Insights into microflare energy distribution and heating mechanisms.

Abstract

We present X-ray imaging and spectral analysis of all microflares the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) observed between March 2002 and March 2007, a total of 25,705 events. These microflares are small flares, from low GOES C Class to below A Class (background subtracted) and are associated with active regions. They were found by searching the 6-12 keV energy range during periods when the full sensitivity of RHESSI's detectors was available (see paper I). Each microflare is automatically analyzed at the peak time of the 6-12 keV emission: the thermal source size is found by forward-fitting the complex visibilities for 4-8 keV, and the spectral parameters (temperature, emission measure, power-law index) are found by forward fitting a thermal plus non-thermal model. The combination of these parameters allows us to present the first statistical analysis of the thermal and non-thermal energy at the peak times of microflares.