The Relation between Magnetic Fields and X-ray Emission for Solar Microflares and Active Regions

TL;DR

This study investigates the relationship between magnetic field parameters and X-ray emission in solar microflares, revealing power-law dependencies and discussing heating mechanisms based on observational data from space-based instruments.

Contribution

It provides new empirical evidence of power-law relations between magnetic flux and X-ray emission in microflares, using high-sensitivity space observations and applying RTV scaling laws.

Findings

Peak flare flux depends on magnetic field strength and flux as a power-law.

Power-law index for active regions is approximately 1.48 in 2.8-36.6 Å range.

Microflares show power-law indices around 3 in 1-8 Å range.

Abstract

We present the result of comparison between magnetic field parameters and the intensity of X-ray emission for solar microflares with Geosynchronous Operational Environmental Satellites (GOES) classes from A0.02 to B5.1. For our study, we used the monochromatic MgXII Imaging Spectroheliometer (MISH), Full-disk EUV Telescope (FET) and Solar PHotometer in X-rays (SphinX) instruments onboard the Complex Orbital Observations Near-Earth of Activity of the Sun-Photon (CORONAS-Photon) spacecraft because of their high sensitivity in soft X-rays. The peak flare flux (PFF) for solar microflares was found to depend on the strength of the magnetic field and total unsigned magnetic flux as a power-law function. In the spectral range 2.8-36.6 \AA\ which shows very little increase related to microflares the power-law index of the relation between the X-ray flux and magnetic flux for active regions is 1.48 $\pm$ 0.86, which is close to the value obtained previously by Pevtsov et al. (Astrophys. J. 598, 1387, 2003) for different types of solar and stellar objects. In the spectral range 1-8 \AA\ the power-law indices for PFF($B$) and PFF($\Phi$) for microflares are 3.87 $\pm$ 2.16 and 3 $\pm$ 1.6 respectively. We also make suggestions on the heating mechanisms in active regions and microflares under the assumption of loops with constant pressure and heating using the Rosner-Tucker-Vaiana (RTV) scaling laws.