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 hours spread over 50 pointings, corresponding to $\sim$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 $109\,\mu\mathrm{Jy}/\mathrm{beam}$ and covers an area $65.31\,\text{deg}^2$ with a resolution of $15.8''$. This wide-area deep-field observation provides a radio source catalog of 5741 sources with flux densities ${\geq}5{\sigma}$. 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 $C_{\ell} = A(1000/{\ell})^{{\beta}}$. Our DGSE amplitude range of $A = 1-20\,{\text{mK}}^2$ and $\beta$ 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.