The MeerKAT Faint Radio Source Population

Abstract

This research presents a comprehensive multi-wavelength characterisation of the faint radio source population in the ADFS, covering approximately 10 deg2 near the South Ecliptic Pole and comprising a catalogue of 19 406 radio sources detected at 1.28 GHz. Using a dedicated cross-matching graphical user interface adapted from the MIGHTEE (2018) project, approximately 66% of the radio sources were successfully associated with optical and infrared counterparts from the HELP–ADFS master catalogue, with redshift information obtained for 8 944 sources (_ 46% of the full sample). During the cross-matching process, two giant radio galaxies (GRGs) were identified: GRG1 at RA _ 71.39_, Dec _ 􀀀52.9_ with a projected size of _ 1.41 Mpc at I = 0.667, and GRG2 at RA _ 70.33_, Dec _ 􀀀53.54_ with a projected size of _ 1.3 Mpc at I _ 0.24. Spectral energy distribution (SED) fitting using CIGALE was successfully performed for 7 874 sources, corresponding to _ 41% of the full radio catalogue and _ 88% of the redshift-identified sample. Based on the Bayesian AGN fraction and WISE colour–colour diagnostics, 2 116 sources were classified as active galactic nuclei (AGN) and 5 759 as star-forming galaxies (SFGs), with 984 sources remaining unclassified due to unconverged or missing SED fits. Approximately 558 AGN (_ 26% of the AGN population) satisfy the WISE AGN wedge selection criteria. The infrared–radio correlationwas investigated using the @IR parameter. The SFG population exhibits a well-defined correlation with a median @IR = 2.635_0.013, while AGN show systematically lower values (@IR _ 1.95 _ 0.016), consistent with excess radio emission arising from non-thermal AGNrelated processes.