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SuperCLASS – II. Photometric redshifts and characteristics of spatially resolved μJy radio sources

Lookup NU author(s): Dr Christopher Hales

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Abstract

© 2020 The Author(s).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 ≈176 000 sources down to iÁB ∼ 24 and present photometric redshifts for 1.4 GHz expanded Multi-Element Radio Linked Interferometer Network (e-MERLIN) and Karl G. Jansky Very Large Array (VLA) detected radio sources found in the central 0.26 deg2. We compile an initial catalogue of 149 radio sources brighter than S1.4 > 75 μJy and find their photometric redshifts span 0 < zphot < 4 with radio luminosities between 1021 and 1025 W Hz−1, with medians of 〈z〉 = 0.55 and 〈L1.4〉 = 1.9 × 1023 W Hz−1, respectively. We find 95 per cent of the μJy radio source sample (141/149) have spectral energy distributions (SEDs) best fit by star-forming templates while 5 per cent (8/149) are better fit by active galactic nuclei (AGN). Spectral indices are calculated for sources with radio observations from the VLA and Giant Metrewave Radio Telescope (GMRT) at 325 MHz, with an average spectral slope of α = 0.59 ± 0.04. Using the full photometric redshift catalogue, 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 centres.

Publication metadata

Author(s): Manning SM, Casey CM, Hung C-L, Battye R, Brown ML, Jackson N, Abdalla F, Chapman S, Demetroullas C, Drew P, Hales CA, Harrison I, Riseley CJ, Sanders DB, Watson RA

Publication type: Article

Publication status: Published

Journal: Monthly Notices of the Royal Astronomical Society

Year: 2020

Volume: 495

Issue: 2

Pages: 1724-1736

Print publication date: 01/06/2020

Online publication date: 02/04/2020

Acceptance date: 01/03/2020

ISSN (print): 0035-8711

ISSN (electronic): 1365-2966

Publisher: Oxford University Press

URL: https://doi.org/10.1093/mnras/staa657

DOI: 10.1093/mnras/staa657

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