Radio Continuum Sources behind the Large Magellanic Cloud

TL;DR

This paper compiles a detailed multi-frequency radio source catalogue behind the Large Magellanic Cloud, identifying various source types and candidates for specific radio source populations, providing valuable data for astrophysical studies.

Contribution

It presents a comprehensive, multi-frequency radio source catalogue covering 144 square degrees with new and legacy data, including classifications and candidate identifications for GPS, CSS, HFP, and IFRS sources.

Findings

Identified 6434 radio sources, with 3789 detected at multiple frequencies.

Estimated median spectral index of -0.89 for sources detected at two frequencies.

Found 10 GPS candidates, 1866 CSS candidates, and 6 HFP candidates.

Abstract

We present a comprehensive multi-frequency catalogue of radio sources behind the Large Magellanic Cloud between 0.2 and 20 GHz, gathered from a combination of new and legacy radio continuum surveys. This catalogue covers an area of $\sim$144~deg$^2$ at angular resolutions from 45 arcsec to $\sim$3 arcmin. We find 6434 discrete radio sources in total, of which 3789 are detected at two or more radio frequencies. We estimate the median spectral index ($\alpha$; where $S_{v}\sim\nu^\alpha$) of $\alpha = -0.89 $ and mean of $-0.88 \pm 0.48$ for 3636 sources detected exclusively at two frequencies (0.843 and 1.384 GHz) with similar resolution (FWHM $\sim$40-45 arcsec). The large frequency range of the surveys makes it an effective tool to investigate Gigahertz Peak Spectrum (GPS), Compact Steep Spectrum (CSS) and Infrared Faint Radio sources populations within our sample. We find 10 GPS candidates with peak frequencies near 5 GHz, from which we estimate their linear size. 1866 sources from our catalogue are (CSS) candidates with $\alpha <-0.8$. We found six candidates for High Frequency Peaker (HFP) sources, whose radio fluxes peak above 5 GHz and no sources with unconstrained peaks and $\alpha~>0.5$. We found optical counterparts for 343 of the radio continuum sources, of which 128have a redshift measurement. Finally, we investigate the population of 123 Infrared Faint Radio Sources (IFRSs) found in this study.