The GLEAM 4-Jy (G4Jy) Sample – III. Further host-galaxy identification, and redshift assessment

ABSTRACT In this paper we present 127 new host-galaxy identifications for G4Jy sources ($S_{\mathrm{151\, MHz}} > 4$ Jy), based on radio images from MeerKAT, the Very Large Array Sky Survey (VLASS), and the Rapid ASKAP (Australian Square Kilometre Array Pathfinder) Continuum Survey (RACS). This includes identifications that result from visual inspection of radio contours on $K_{\mathrm{S}}$-band images, as opposed to the AllWISE-W1 images that were used for the original set of overlays when defining the G4Jy Sample (Papers I and II). Our aim is to achieve 100 per cent spectroscopic completeness for the sample, where all of the spectroscopy is available in digital form online. For now, we have gathered (i) digital optical spectroscopy for 34 per cent of the sample, (ii) photometric redshifts for an additional 21 per cent of the sample, and (iii) further redshifts found through the NASA/IPAC Extragalactic Database (but not recently verified). Our assessment of the redshifts includes visual inspection of all of the digital spectroscopy, and re-fitting redshift templates where necessary. The resulting redshift range is (currently) $0.0 < z < 3.6$. We also present 151-MHz luminosities and linear sizes for the G4Jy Sample, based on initial analysis.