The faint radio source population at 15.7 GHz - II. Multi-wavelength properties
Date
2015Author
Whittam, I.H.
Riley, J.M.
Green, D.A.
Jarvis, Matt
Vaccari, M.
Metadata
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A complete, flux density limited sample of 96 faint (> 0:5 mJy) radio sources is selected
from the 10C survey at 15.7 GHz in the Lockman Hole. We have matched this sample to a
range of multi-wavelength catalogues, including SERVS, SWIRE, UKIDSS and optical data;
multi-wavelength counterparts are found for 80 of the 96 sources and spectroscopic redshifts
are available for 24 sources. Photometric reshifts are estimated for the sources with multiwavelength
data available; the median redshift of the sample is 0.91 with an interquartile range
of 0.84. Radio-to-optical ratios show that at least 94 per cent of the sample are radio loud,
indicating that the 10C sample is dominated by radio galaxies. This is in contrast to samples
selected at lower frequencies, where radio-quiet AGN and starforming galaxies are present
in significant numbers at these flux density levels. All six radio-quiet sources have rising
radio spectra, suggesting that they are dominated by AGN emission. These results confirm
the conclusions of Paper I that the faint, flat-spectrum sources which are found to dominate
the 10C sample below 1 mJy are the cores of radio galaxies. The properties of the 10C
sample are compared to the SKADS Simulated Skies; a population of low-redshift starforming
galaxies predicted by the simulation is not found in the observed sample.