Discovery of correlated evolution in solar noise storm source parameters: Insights on magnetic field dynamics during a microflare

Abstract

A solar type-I noise storm is produced by accelerated particle beams generated at active regions undergoing magnetic field restructuring. Their intensity varies by orders of magnitude within sub-second and sub-MHz scales. But, the morphological evolution of these sources are not studied at these scales, due to the lack of required imaging cadence and fidelity in metrewave bands. Using data from the Murchison Widefield Array (MWA), this work explores the co-evolution of size, sky-orientation and intensity of a noise storm source associated with a weak microflare. The work presents the discovery of two correlated modes of evolution in the source parameters: a sausage like \s\ mode where the source intensity and size shows an anti-correlated evolution; and a torsional like \T\ mode where the source size and sky-orientation shows a correlated evolution. A flare mediated mode conversion is observed from \T\ to \s\ for the first time in these sources. These results support the idea of build up of magnetic stress energy in braided active region loops, which later go unstable causing flares and particle acceleration until they relax to a minimally braided state. The discovered mode conversion can be a future diagnostic to such active region phenomena.

5 pages main paper, 5 figures, 1 page appendix

References in corpus (7)

• Array Programming with NumPy
• The formation heights of coronal shocks from 2D density and Alfvén speed maps
• Effect of collisions and magnetic convergence on electron acceleration and transport in reconnecting twisted solar flare loops
• 4D Data Cubes from Radio-Interferometric Spectroscopic Snapshot Imaging
• Unsupervised generation of high dynamic range solar images: A novel algorithm for self-calibration of interferometry data
• Spectral Structures and Their Generation Mechanisms for Solar Radio Type-I Bursts
• Probing Twisted Magnetic Field Using Microwave Observations in an M Class Solar Flare on 11 February, 2014

Cited by in corpus (5)

• A search for counterparts of quiet sun radio transients in extreme ultraviolet data
• Detection of weak ubiquitous impulsive nonthermal emissions from the solar corona
• Insights from snapshot spectroscopic radio observations of a weak Type I noise storm
• Robust absolute solar flux density calibration for the Murchison Widefield Array
• Working Principle of the Calibration Algorithm for High Dynamic Range Solar Imaging with Square Kilometre Array Precursor