J/A+A/602/A2ivo://CDS.VizieR/J/A+A/602/A2doi:10.26093/cds/vizier.36020002CDSSmolcic V.Delvecchio I.Zamorani G.Baran N.Novak M.Delhaize J.,Schinnerer E.Berta S.Bondi M.Ciliegi P.Capak P.Civano F.,Karim A.Le Fevre O.Ilbert O.Laigle C.Marchesi S.McCracken H.J.,Tasca L.Salvato M.Vardoulaki E.2017-07-03T13:43:41Z2017-06-13T08:27:22ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frsurveysradio-galaxiesactive-galactic-nucleiinfrared-sourcesWe study the composition of the faint radio population selected from the VLA-COSMOS 3GHz 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 ~2.3uJy/beam, cataloging 10,830 sources above 5sigma, 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), we 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 NIR bands), reaching out to z~6. We further classify the sources as star forming galaxies or AGN based on various criteria, such as X-ray luminosity, observed MIR color, UV-FIR spectral-energy distribution, rest-frame NUV-optical color corrected for dust extinction, and radio-excess relative to that expected from the hosts' star-formation rate. We separate the AGN into sub-samples dominated by low-to-moderate and moderate-to-high radiative luminosity AGN, candidates for high- redshift analogues to local low- and high-excitation emission line AGN, respectively. We study the fractional contributions of these sub-populations down to radio flux levels of ~11uJy at 3GHz (or ~20uJy at 1.4GHz assuming a spectral index of -0.7). We find that the dominant fraction at 1.4GHz flux densities above ~200uJy is constituted of low-to-moderate radiative luminosity AGN. Below densities of ~100uJy the fraction of star-forming galaxies increases to ~60%, followed by the moderate-to-high radiative luminosity AGN (~20%), and low-to-moderate radiative luminosity AGN (~20%). Based on this observational evidence, we extrapolate the fractions down to sensitivities of the Square Kilometer Array (SKA). Our 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.2017A&A...602A...2Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/602/A2CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/284 : COSMOS Multi-Wavelength Photometry Catalog (Capak+, 2007)J/ApJ/644/100 : SDSS quasars in the COSMOS field (Prescott+, 2006)J/ApJS/172/523 : COSMOS field Ly{alpha} emitters at z~5.7 (Murayama+, 2007)J/ApJS/172/368 : XMM-Newton survey in COSMOS field. IV. (Mainieri+, 2007)J/ApJS/175/128 : H{alpha} emitting galaxies in COSMOS-2 field (Shioya+, 2008)J/MNRAS/385/2225 : AzTEC millimetre survey of COSMOS field (Scott+, 2008)J/ApJS/184/158 : Chandra COSMOS survey I. (Elvis+, 2009)J/A+A/497/635 : XMM wide-field survey in COSMOS field (Cappelluti+, 2009)J/AJ/138/1261 : Spitzer/MIPS observations of the COSMOS field (Frayer+ 2009)J/ApJ/709/572 : COSMOS 70um sources (Kartaltepe+, 2010)J/ApJ/716/348 : The XMM-Newton survey of the COSMOS field (Brusa+, 2010)J/ApJ/760/128 : COSMOS 4<z<6 sources Ly{alpha} emission (Mallery+, 2012)J/MNRAS/436/1919 : SCUBA observations of COSMOS galaxies (Casey+, 2013)J/A+A/567/A76 : COSMOS field radio-loud AGN population at z>1 (Baldi+, 2014)J/ApJ/819/62 : The COSMOS-Legacy Survey (CLS) catalog (Civano+, 2016)J/AJ/128/1974 : The VLA-COSMOS survey (Schinnerer+, 2004)J/ApJS/172/46 : VLA-COSMOS survey. II. (Schinnerer+, 2007)J/ApJS/188/384 : The VLA-COSMOS survey. IV. (Schinnerer+, 2010)J/MNRAS/443/2590 : The VLA-COSMOS Survey. V. 324MHz (Smolcic+, 2014)J/A+A/602/A1 : VLA-COSMOS 3 GHz Large Project. I. (Smolcic+, 2017)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/602/A2https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/602/A2http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/602/A2https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/602/A2https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/602/A2http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/602/A2GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/602/A2/table1 (VLA-COSMOS 3GHz source counterpart catalog)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/602/A2/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/602/A2/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/602/A2/table1?GETtext/xml+votable180.050000true149.647713892.0954650.0055555555555555565/6814 6/27245 27247 273441.987820871092403e-24 1.987820871092403e-24https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/602/A2?format=asciiRadioInfrareddefaultJ/A+A/602/A2/table1VLA-COSMOS 3GHz source counterpart catalogrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintVLA[1/10966] Numerical ID of the VLA 3GHz sourcemeta.id;meta.mainintRAJ2000VLA right ascension at 3GHz (J2000)degpos.eq.ra;meta.mainDEJ2000VLA declination at 3GHz (J2000)degpos.eq.dec;meta.mainMulti[0/1] Multi-component flag (1 for multi-component radio source)meta.codeintCatCtpCounterpart catalog (1)meta.id;meta.datasetcharCtpID of the optical/MIR counterpartmeta.idintRAcdegCounterpart right ascension (J2000)degpos.eq.raDEcdegCounterpart declination (J2000)degpos.eq.decSepAngular distance between the VLA source and its counterpart (2)arcsecmeta.id.assoc;pos.angDistancefloatPfalse? False-match probability (3)stat.fit.goodnessdoublenullablezbest? Best available redshiftsrc.redshift;pos.heliocentricdoublenullableF3GHzTotal integrated flux density at 3GHzuJyphot.flux.density;em.radio.1500-3000MHzdoublelogL10cm? Radio luminosity at 10cm (3GHz)log(W.Hz**-1)phys.luminosity;em.radio.1500-3000MHzdoublenullablelogL21cm? Radio luminosity at 21cm (1.4GHz) (4)log(W.Hz**-1)phys.luminosity;em.radio.750-1500MHzdoublenullablelogLTIRSF? 8-1000um luminosity of the host galaxy (5)log(solLum)phys.luminosity;em.IRdoublenullableSFR? Star-formation rate from LTIRSF (6)solMass/yrphys.SFRdoublenullableXrayAGN[T/F] Boolean Flag for X-ray AGNmeta.codecharMIRAGN[T/F] Boolean Flag for mid-IR AGNmeta.codecharSEDAGN[T/F] Boolean Flag for SED AGNmeta.codecharQMLAGN[T/F] Boolean Flag for Quiescent MLAGNmeta.codecharSFG[T/F] Boolean Flag for star-forming galaxiesmeta.codecharCleanSFG[T/F] Boolean Flag for no radio-excess SFGsmeta.codecharHLAGN[T/F] Boolean Flag for HLAGNmeta.codecharMLAGN[T/F] Boolean Flag for MLAGNmeta.codecharRExcess[T/F] Boolean Flag for (3sigma) radio-excessmeta.codecharflagC15[0/8] Flag for the area of 1.77sq.degrees (7)meta.code.errorint