4D Data Cubes from Radio-Interferometric Spectroscopic Snapshot Imaging

TL;DR

This paper presents a formalism to generate 4D data cubes from radio-interferometric solar images, enabling detailed tracking of solar emissions across spatial, spectral, and temporal dimensions, and introduces SPREDS for regional spectral analysis.

Contribution

The paper introduces a novel method to create 4D data cubes and SPREDS from interferometric solar images, enhancing the analysis of solar radio emissions.

Findings

First calibrated solar maps from MWA

Demonstration of 4D data cubes for solar imaging

Introduction of SPREDS for regional spectral analysis

Abstract

The new generation of low radio-frequency interferometric arrays have enabled the imaging of the solar corona at high spectro-temporal resolutions and sensitivity. In this article we introduce and implement a formalism to generate flux density and brightness temperature ($T_{\mathrm B}$) maps from such images, using independently obtained disc-integrated solar flux density dynamic spectra. These images collectively generate a 4D data cube, with axes spanning angular coordinates ($\theta,\phi$), frequency ($\nu$) and time ($t$). This 4D data cube is the most informative data product which can be generated from interferometric radio data. It will allow us to track solar emission simultaneously in these four dimensions. We also introduce SPatially REsolved Dynamic Spectra (SPREDS), named in analogy to the usual dynamic spectra. For any arbitrary region, ($\theta_i,\phi_j$), in the maps, these 2D projections of the 4D data cube correspond to the dynamic spectrum of emission arising from there. We show examples of these data products using observations from the Murchison Widefield Array (MWA). These are also the first calibrated solar maps from the MWA.