4D Data Cubes from Radio-Interferometric Spectroscopic Snapshot Imaging

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 ($\theta ,\varphi$), 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, (${\theta }_i,{\varphi }_j$), 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.

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• Science with the Murchison Widefield Array: Phase I Results and Phase II Opportunities
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• Exoplanet Modulation of Stellar Coronal Radio Emission
• Detection of weak ubiquitous impulsive nonthermal emissions from the solar corona
• Synthetic Radio Imaging for Quiescent and CME-flare Scenarios
• 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
• Multiple Regions of Nonthermal Quasi-Periodic Pulsations during the Impulsive Phase of a Solar Flare
• Exoplanet Radio Transits as a Probe for Exoplanetary Magnetic Fields -- Time-dependent MHD Simulations
• Preparing for Solar and Heliospheric Science with the SKAO: An Indian Perspective
• Solar Observation with MeerKAT: Demonstration of Technical Readiness and Initial Science Highlight
• Combined Radio and Space-based Solar Observations: From Techniques to New Results