A weak coronal heating event associated with periodic particle acceleration episodes

Abstract

Weak heating events are frequent and ubiquitous in solar corona. They derive their energy from the local magnetic field and form a major source of local heating, signatures of which are seen in EUV and X-ray bands. Their radio emission arise from various plasma instabilities that lead to coherent radiation, making even a weak flare appear very bright. The radio observations hence probe non-equilibrium dynamics providing complementary information on plasma evolution. However, a robust study of radio emission from a weak event among many simultaneous events, requires high dynamic range imaging at sub-second andsub-MHz resolutions owing to their high spectro-temporal variability. Such observations were not possible until recently.This is among the first spatially resolved studies of an active region loop hosting a transient brightening (ARTB) and dynamically linked to a metrewave type-I noise storm. It uses imaging observations at metrewave, EUV and X-ray bands, along with magnetogram data. We believe this is the first spectroscopic radio imaging study of a type-I source, the data for which was obtained using the Murchison Widefield Array. We report the discovery of 30 s quasi-periodic oscillations (QPOs) in the radio light curve, riding on a coherent baseline flux. The strength of the QPOs and the baseline flux enhanced during a mircoflare associated with the ARTB. Our observations suggest a scenario where magnetic stress builds up over an Alfvén timescale (30s) across the typical magnetic field braiding scale and then dissipates via a cascade of weak reconnection events.

21 Pages and 13 figures

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Cited by in corpus (17)

• The Low-Frequency Solar Corona in Circular Polarization
• First radio evidence for impulsive heating contribution to the quiet solar corona
• Propagation Effects in Quiet Sun Observations at Meter Wavelengths
• Imaging-spectroscopy of a band-split type II solar radio burst with the Murchison Widefield Array
• Discovery of correlated evolution in solar noise storm source parameters: Insights on magnetic field dynamics during a microflare
• Tackling the Unique Challenges of Low-frequency Solar Polarimetry with the Square Kilometre Array Low Precursor: The Algorithm
• A search for counterparts of quiet sun radio transients in extreme ultraviolet data
• Insights from snapshot spectroscopic radio observations of a weak Type I noise storm
• Working Principle of the Calibration Algorithm for High Dynamic Range Solar Imaging with Square Kilometre Array Precursor
• Robust absolute solar flux density calibration for the Murchison Widefield Array
• Tackling the Unique Challenges of Low-frequency Solar Polarimetry with the Square Kilometre Array Low Precursor: Pipeline Implementation
• Multiple Regions of Nonthermal Quasi-Periodic Pulsations during the Impulsive Phase of a Solar Flare
• Preparing for Solar and Heliospheric Science with the SKAO: An Indian Perspective
• New Insights into Type-I Solar Noise Storms from High Angular Resolution Spectroscopic Imaging with the Upgraded Giant Metrewave Radio Telescope
• Ultra-Wideband, Multi-epoch Radio Study of the First Discovered `Main sequence Radio Pulse emitter' CU Vir
• Observation and Modeling of Small Spatial Structures of Solar Radio Noise Storms using the uGMRT
• Characterizing the Spectral Structure of Weak Impulsive Narrowband Quiet Sun Emissions