J/MNRAS/463/2997ivo://CDS.VizieR/J/MNRAS/463/2997doi:10.26093/cds/vizier.74632997CDSMahony E.K.Morganti R.Prandoni I.Van Bemmel I.M.Shimwell T.W.,Brienza M.Best P.N.Bruggen M.Calistro Rivera G.De Gasperin F.,Hardcastle M.J.Harwood J.J.Heald G.Jarvis M.J.Mandal S.,Miley G.K.Retana-montenegro E.Rottgering H.J.A.Sabater J.Tasse C.,Van Velzen S.Van Weeren R.J.Williams W.L.White G.J.2024-08-16T20:19:13Z2019-05-29T17:11:56ZCDS support team

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

cds-question@unistra.frsurveysradio-galaxiesradio-continuum-emissionThe Lockman Hole is a well-studied extragalactic field with extensive multi-band ancillary data covering a wide range in frequency, essential for characterizing the physical and evolutionary properties of the various source populations detected in deep radio fields (mainly star-forming galaxies and AGNs). In this paper, we present new 150-MHz observations carried out with the LOw-Frequency ARray (LOFAR), allowing us to explore a new spectral window for the faint radio source population. This 150-MHz image covers an area of 34.7 square degrees with a resolution of 18.6x14.7-arcsec and reaches an rms of 160{mu}Jy/beam at the centre of the field. As expected for a low-frequency selected sample, the vast majority of sources exhibit steep spectra, with a median spectral index of {alpha}_150_^1400^=-0.78+/-0.015. The median spectral index becomes slightly flatter (increasing from {alpha}_150_^1400^=-0.84 to {alpha}_150_^1400^=-0.75) with decreasing flux density down to S_150_ ~10mJy before flattening out and remaining constant below this flux level. For a bright subset of the 150-MHz selected sample, we can trace the spectral properties down to lower frequencies using 60-MHz LOFAR observations, finding tentative evidence for sources to become flatter in spectrum between 60 and 150MHz. Using the deep, multi-frequency data available in the Lockman Hole, we identify a sample of 100 ultra-steep-spectrum sources and 13 peaked-spectrum sources. We estimate that up to 21 per cent of these could have z>4 and are candidate high-z radio galaxies, but further follow-up observations are required to confirm the physical nature of these objects.2016MNRAS.463.2997Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/463/2997CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/329/482 : ROSAT Deep Survey in the Lockman Hole (Hasinger+, 1998)J/PASJ/53/445 : ASCA Deep survey in Lockman Hole Field (Ishisaki+, 2001)J/A+A/398/901 : VLA survey at 6 cm in the Lockman Hole (Ciliegi+, 2003)J/AJ/125/2521 : 2MASS6x survey of the Lockman Hole (Beichman+, 2003)J/A+A/413/843 : Far IR survey in the Lockman Hole (Kawara+, 2004)J/A+A/427/23 : 14.3um survey in the Lockman Hole (Fadda+, 2004)J/A+A/427/773 : ISOCAM 14.3{mu}m Deep Survey in Lockman HoleJ/A+A/444/79 : XMM observations of Lockman Hole brightest AGNsJ/A+A/473/105 : Lockman Hole AGN variability with XMM (Mateos+, 2007)J/A+A/479/283 : XMM observations of the Lockman Hole (Brunner+, 2008)J/A+A/487/475 : X-ray variability of AGNs in Lockman Hole (Papadakis+, 2008)J/MNRAS/387/1037 : 610-MHz survey of Lockman Hole with GMRT (Garn+, 2008)J/ApJS/185/433 : SWIRE/Chandra survey in Lockman Hole Field (Wilkes+, 2009)J/A+A/514/A10 : AGNs in submm-selected Lockman Hole galaxiesJ/A+A/529/A135 : AGN Opt/IR properties in Lockman Hole (Rovilos+, 2011)J/ApJS/198/1 : Photometry catalogs for the Lockman Hole (Fotopoulou+, 2012)J/A+A/551/A97 : Lockman Hole/XMM VLBI observations (Middelberg+, 2013)J/MNRAS/397/281 : Radio imaging in Lockman Hole (Ibar+, 2009)J/MNRAS/462/2934 : Lockman Hole North 3GHz catalogue (Vernstrom+, 2016)J/ApJ/856/67 : VLA 3GHz radio source catalog in Lockman Holehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/463/2997https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/463/2997http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/463/2997https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/463/2997https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/463/2997http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/463/2997GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/463/2997/table4 (Lockman-WSRT catalogue)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/463/2997/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/463/2997/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/463/2997/table4?GETtext/xml+votable180.050000true165.35916757.6230830.0055555555555555565/1517 1528 6/6047 6076-6077 6088 6090 61209.939104750406538e-26 9.939104750406538e-26https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/463/2997?format=asciiRadiodefaultJ/MNRAS/463/2997/table4Lockman-WSRT cataloguerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameLOFAR name (JHHMMSS+DDMMSS)meta.id;meta.maincharRAJ2000LOFAR 150MHz Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000LOFAR 150MHz Declination (J2000)pos.eq.dec;meta.mainSt150Integrated 150MHz flux densitymJyphot.flux.density;em.radio.100-200MHzfloate_St150rms uncertainty on St150mJystat.errorfloatrmsLocal rmsmJystat.stdev;instr.det.noisefloatFlag[SCM] Source flag (from pybdsm)meta.code.errorcharWSRTWSRT name (LHWJHHMMSS+DDMMSSA)meta.idcharRAW? WSRT Right ascension (J2000)pos.eq.ranullableDEW? WSRT Declination (J2000)pos.eq.decnullablel_Si1.4GHzLimit flag on Si1.4GHzmeta.code.errorcharSi1.4GHzIntegrated 1.4-GHz flux densitymJyphot.flux.density;em.radio.750-1500MHzfloate_Si1.4GHz? rms uncertainty on Si1.4GHzmJystat.errorfloatnullableSp1.4GHz? Peak 1.4-GHz flux densitymJyphot.flux.density;em.radio.750-1500MHz;stat.maxfloatnullablee_Sp1.4GHz? rms uncertainty on Sp1.4GHzmJystat.errorfloatnullablemaj? Deconvolved 1.4-GHz source major axis (1)arcsecphys.angSize;em.radio.750-1500MHzfloatnullablemin? Deconvolved 1.4-GHz source minor axis (1)arcsecphys.angSize;em.radio.750-1500MHzfloatnullablePA[]? Deconvolved 1.4-GHz source position angle (1)degpos.posAngfloatnullablel_SpIndexLimit flag on SpIndexmeta.code.errorcharSpIndexSpectral index between 150MHz and 1.4GHz, {alpha}^1400^_150_spect.index;em.radio.100-200MHzfloatFlagIDIdentification flag (2)meta.code.errorcharSimbadSimbad column added by the CDSmeta.ref.urlchar