The e-MERLIN SuperCLASS legacy survey : photometric redshifts and characteristics of spatially resolved [mu] Jy radio sources

We present optical and near-infrared imaging covering a ~1.53 deg² region in the Super-Cluster Assisted Shear Survey (SuperCLASS) field, which aims to make the first robust weak lensing measurement at radio wavelengths. We derive photometric redshifts for [approximately equal to] 176,000 sources down to i'[subscript AB]~24 and present photometric redshifts for 1.4 GHz e-MERLIN and VLA detected radio sources found in the central 0.26 deg². We compile an initial catalog of 149 radio sources brighter than S₁.₄ > 75 µJy and find their photometric redshifts span 0 < z [subscript phot] <4 with radio luminosities between 10²¹ - 10²⁵ W Hz⁻¹, with medians of = 0.55 and <L₁.₄> =1.9 x 10²³ W Hz⁻¹ respectively. We find 95% of the µJy radio source sample (141/149) have SEDs best fit by star-forming templates while 5% (8/149) are better fit by AGN. Spectral indices are calculated for sources with radio observations from VLA and GMRT at 325 MHz, with an average spectral slope of α=0.59±0.04. Using the full photometric redshift catalog we construct a density map at the redshift of the known galaxy clusters, z=0.20±0.08. Four of the five clusters are prominently detected at > 7 σ in the density map and we confirm the photometric redshifts are consistent with previously measured spectra from a few galaxies at the cluster centers.