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

Abstract

We present the result of a 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), the Full-disk EUV Telescope (FET), and the 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 on the total unsigned magnetic flux as a power-law function. In the spectral range 2.8 – 36.6 Å, 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 $1.48 \pm0.86$, 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 Å, the power-law indices for $\mathrm{PFF}(B)$ and $\mathrm{PFF}(\Phi)$ for microflares are $3.87 \pm2.16$ and $3 \pm1.6$, 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 scaling laws.