# A weak coronal heating event associated with periodic particle acceleration episodes

## TL;DR

This study presents the first spatially resolved radio imaging of a weak coronal heating event linked to periodic particle acceleration, revealing 30-second quasi-periodic oscillations and insights into magnetic stress dissipation in the solar corona.

## Contribution

It provides the first spectroscopic radio imaging analysis of a type-I noise storm using the Murchison Widefield Array, uncovering quasi-periodic oscillations associated with weak coronal heating events.

## Key findings

- Discovery of 30 s quasi-periodic oscillations in radio light curves.
- Enhanced flux during microflares linked to ARTB.
- Magnetic stress buildup and dissipation via weak reconnection events.

## 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 Alfv\'{e}n timescale (30s) across the typical magnetic field braiding scale and then dissipates via a cascade of weak reconnection events.