Source Imaging of a Moving Type-IV Solar Radio Burst and its Role in Tracking Coronal Mass Ejection From the Inner to the Outer Corona

TL;DR

This study demonstrates how source imaging of moving type-IV solar radio bursts can effectively track coronal mass ejections from the inner to the outer corona, revealing their association with eruptive structures and providing insights into their emission mechanisms.

Contribution

The paper presents a combined multi-wavelength analysis of a moving type-IV radio burst, highlighting its potential for continuous CME tracking and insights into its emission properties.

Findings

t-IVm sources correlate with eruptive EUV structures in the inner corona

t-IVm sources associate with CME core in the outer corona

t-IVm burst shows broken power-law spectra with high brightness temperature

Abstract

Source imaging of solar radio bursts can be used to track energetic electrons and associated magnetic structures. Here we present a combined analysis of data at different wavelengths for an eruption associated with a moving type-IV (t-IVm) radio burst. In the inner corona, the sources are correlated with a hot and twisted eruptive EUV structure, while in the outer corona the sources are associated with the top front of the bright core of a white light coronal mass ejection (CME). This reveals the potential of using t-IVm imaging data to continuously track the CME by lighting up the specific component containing radio-emitting electrons. It is found that the t-IVm burst presents a clear spatial dispersion with observing frequencies. The burst manifests broken power-law like spectra in brightness temperature, which is as high as $10^7$-$10^9$ K while the polarization level is in-general weak. In addition, the t-IVm burst starts during the declining phase of the flare with a duration as long as 2.5 hours. From the differential emission measure analysis of AIA data, the density of the T-IVm source is likely at the level of 10$^8$ cm$^{-3}$ at the start of the burst, and the temperature may reach up to several MK. These observations do not favor gyro-synchrotron to be the radiation mechanism, yet in line with a coherent plasma emission excited by energetic electrons trapped within the source. Further studies are demanded to elucidate the emission mechanism and explore the full diagnostic potential of t-IVm bursts.