Investigating Radio Source Population and Spatial Characteristics of Diffuse Galactic Synchrotron Emission in the GAMA-23 Field with uGMRT Band-3

Abstract

We present upgraded Giant Meterwave Radio Telescope (uGMRT) Band-3 observations of the Galaxy and Mass Assembly (GAMA)-23 field. The observations consist of a total of 33 hr spread over 50 pointings, corresponding to ∼56 minutes per pointing at the central frequency of 325 MHz. The final image mosaicked from these pointings has a central off-source rms noise of 109 μJy beam−1 and covers an area 65.31 deg2 with a resolution of 15 (Formula presented) .″ 8. This wide-area deep-field observation provides a radio source catalog of 5741 sources with flux densities ≥5σ. We present complementary uGMRT observations overlapping with the high-frequency Australian Square Kilometre Array Pathfinder Evolutionary Map of the Universe survey. We derived the spectral index from the matched sources in the GAMA-23 field for the first time. We have studied the statistical properties of diffuse Galactic synchrotron emission (DGSE) in the GAMA-23 field using six different latitude target pointings. We fitted DGSE in the form of power law Cℓ = A(1000/ℓ)β. Our DGSE amplitude range of A = 1–20 mK2 and β varies between 1.5 and 2.4. This work presents one of the first characterizations of DGSE in the southern sky at 325 MHz, setting a precedent for foreground modeling required for sensitive radio observations with the upcoming SKA. © 2026. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.