Imaging Spectroscopy of Solar Radio Burst Fine Structures

TL;DR

This study uses LOFAR radio observations to distinguish between intrinsic solar radio burst properties and propagation effects, enabling more accurate source characterization and insights into coronal turbulence.

Contribution

It provides the first quantitative spatial and frequency analysis of solar radio burst fine structures with high-resolution imaging, highlighting the dominance of propagation effects.

Findings

Radio-wave propagation effects dominate observed burst images.

Enables more accurate estimates of source brightness temperatures.

Opens new avenues for studying coronal turbulence mechanisms.

Abstract

Solar radio observations provide a unique diagnostic of the outer solar atmosphere. However, the inhomogeneous turbulent corona strongly affects the propagation of the emitted radio waves, so decoupling the intrinsic properties of the emitting source from the effects of radio-wave propagation has long been a major challenge in solar physics. Here we report quantitative spatial and frequency characterization of solar radio burst fine structures observed with the LOw Frequency Array (LOFAR), an instrument with high time resolution that also permits imaging at scales much shorter than those corresponding to radio-wave propagation in the corona. The observations demonstrate that radio-wave propagation effects, and not the properties of the intrinsic emission source, dominate the observed spatial characteristics of radio burst images. These results permit more accurate estimates of source brightness temperatures, and open opportunities for quantitative study of the mechanisms that create the turbulent coronal medium through which the emitted radiation propagates.