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Description
In the reference paper, the authors study the composition of the faint radio population selected from the VLA-COSMOS 3-GHz Large Project, a radio continuum survey performed at 10-cm wavelength. The survey covers a 2.6 square degree area with a mean rms of ~2.3 µJy/beam (µJy/beam), cataloguing 10,830 sources above 5 sigma, and enclosing the full 2 square degree COSMOS field. By combining these radio data with optical, near-infrared (UltraVISTA), and mid-infrared (Spitzer/IRAC) data, as well as X-ray data (Chandra), the authors find counterparts to radio sources for ~93% of the total radio sample in the unmasked areas of the COSMOS field, i.e., those not affected by saturated or bright sources in the optical to near-IR (NIR) bands, reaching out to z ~ 6. They further classify the sources as star-forming galaxies or AGN based on various criteria, such as X-ray luminosity, observed mid-infrare (MIR) color, UV-far-infrared (FIR) spectral-energy distribution (SED), rest-frame near-ultraviolet (NUV)-optical color corrected for dust extinction, and radio-excess relative to that expected from the the hosts' star-formation rate. The authors separate the AGN into sub-samples dominated by low-to-moderate and moderate-to-high radiative luminosity AGN, i.e., candidates for high-redshift analogs to local low- and high-excitation emission line AGN, respectively. They study the fractional contributions of these sub-populations down to radio flux levels of ~11 uJy at 3 GHz (or ~20 uJy at 1.4 GHz assuming a spectral index of -0.7), and find that the dominant fraction at 1.4 GHz flux densities above ~200 uJy is constituted of low-to-moderate radiative luminosity AGN MLAGN). Below densities of ~100 uJy the fraction of star-forming galaxies (SFG) increases to ~60%, followed by the moderate-to-high radiative luminosity AGN (HLAGN) with ~20%, and MLAGN with ~20%. Based on this observational evidence, the authors extrapolate the fractions down to sensitivities of the Square Kilometer Array (SKA). Their estimates suggest that at the faint flux limits to be reached by the (Wide, Deep, and UltraDeep) SKA1 surveys, a selection based only on radio flux limits can provide a simple tool to efficiently identify samples highly (>75%) dominated by star-forming galaxies. This table contains the full list of 9,161 optical-MIR counterparts collected over the largest unmasked area accessible to each catalog, being 1.77, 1.73, and 2.35 square degrees for COSMOS2015, i-band, and IRAC catalogs, respectively. The catalog lists the counterpart IDs, properties, as well as the individual criteria used in this work to classify these radio sources. The authors note that complete, non-overlapping samples within a well defined, effective area of 1.77 square degrees (COSMOS2015 masked area flag_C15 = 0, can be formed by combining (i) HLAGN, MLAGN, and clean SFG samples, or, alternatively, (ii) the radio-excess and no-radio-excess samples. This table was created by the HEASARC in July 2017 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/602/A2">CDS Catalog J/A+A/602/A2</a> file table1.dat, the VLA-COSMOS 3-GHz Large Project multiwavelength counterpart catalog. This is a service provided by NASA HEASARC .
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