J/ApJ/728/23ivo://CDS.VizieR/J/ApJ/728/23doi:10.26093/cds/vizier.17280023CDSWorseck G.Prochaska J.X.2017-11-28T13:21:31Z2012-10-16T15:43:53ZCDS support team

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

cds-question@unistra.frultraviolet-photometryvisible-astronomysloan-photometryredshiftedquasarssurveysWe study the small population of high-redshift (z_em_>2.7) quasars detected by the Galaxy Evolution Explorer(GALEX), whose far-UV emission is not extinguished by intervening HI Lyman limit systems. We correlate almost all verified z_em_>2.7 quasars to the GALEX GR4 source catalog covering ~25000deg^2^, yielding 304 sources detected at signal-to-noise ratio (S/N)>3. However, ~50% of these are only detected in the GALEX NUV band, signaling the truncation of the FUV flux by low-redshift optically thick Lyman limit systems. We regard 52 quasars detected at S/N>3 to be most promising for Hubble Space Telescope follow-up, with an additional 114 quasars if we consider S/N>2 detections in the FUV. Combining the statistical properties of HI absorbers with the Sloan Digital Sky Survey (SDSS) quasar luminosity function, we predict a large all-sky population of ~200 quasars with z_em_>2.7 and i<~19 that should be detectable at the HeII edge at m_304_<21. However, SDSS provides just half of the NUV-bright quasars that should have been detected by SDSS and GALEX. With mock quasar photometry we revise the SDSS quasar selection function, finding that SDSS systematically misses quasars with blue u-g<~2 colors at 3<~z_em_<~3.5 due to overlap with the stellar locus in color space.2011ApJ...728...23Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/728/23CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)VII/258 : Quasars and Active Galactic Nuclei (13th Ed.) (Veron+ 2010)II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)J/ApJS/193/28 : Galaxy survey around 20 UV-bright quasars (Prochaska+, 2011)J/MNRAS/399/728 : UV-bright sources behind M31 halo (Fittingoff+, 2009)J/AJ/137/3761 : Ultraviolet quasi-stellar objects (Bianchi+, 2009)J/ApJS/185/20 : Additional HeII quasar sightlines (Syphers+, 2009)J/ApJ/690/1181 : UV-bright quasars (Syphers+, 2009)J/MNRAS/383/1513 : 2MASS, SDSS and FIRST fluxes of QSOs (Labita+, 2008)J/AJ/133/1780 : GALEX/SDSS quasar catalog (Trammell+, 2007)J/ApJ/664/53 : UV photometry of GALEX QSO candidates (Atlee+, 2007)J/ApJS/134/35 : Large Bright Quasar Survey emission lines (Forster+, 2001)J/A+AS/111/169 : UV-excess quasar candidates (Moreau+, 1995)http://www.sdss.org/ : SDSS home pagehttp://galex.stsci.edu/GR4/ : GALEX GR4/GR5 at MASThttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/728/23https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/728/23http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/728/23https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/728/23https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/728/23http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/728/23GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/728/23/table3 (*Promising targets to search for HeII (GALEX S/N>3 and (FUV-NUV)<1mag))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/728/23/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/728/23/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/728/23/table3?GETtext/xml+votable180.050000true212.852625-2.49516670.005555555555555556Cone search capability for table J/ApJ/728/23/table4 (*Further quasars with potential FUV flux (GALEX S/N(FUV)>2))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/728/23/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/728/23/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/728/23/table4?GETtext/xml+votable180.050000true8.8509583-28.620750.0055555555555555566/4299 4322 4378 4693 4698 4950 4971 4976 5012 5083 5118 5145 5182 5184 5228 5293 5420 5460 5654 5708 5742 5800 6042 6069 6073 6231 6619 6620 7190 7232 7268 7606 8234 8255 8437 8517 8521 8630 8653 8722 8736 8904 8912 8913 9173 9195 9208 9465 9471 9515 9825 9999 10247 10295 10381 10405 10703 10833 10856 10976 11084 11230 11252 11454 11529 11916 16461 16467 16477 16481 16539 16646 16652 17032 17294 17407 17522 17772 17827 17834 18023 18028 18042 18065 18075 18078 18081 18387 18776 18782 18790 18791 18793 18839 19052 19059 19060 19751 20005 22008 25575 25913 25958 25964 26099 26177 26199 26212 26245 26269 26270 26421 26429 26430 26433 26448 26492 26520 26989 27429 27486 27646 27657 27737 28041 28058 28153 28222 28450 28536 28571 28610 28627 28632 28671 30031 31402 32442 32446 35213 35267 35272 35438 35534 35542 35580 35646 35664 35680 35746 35765 35935 35989 36019 36079 36268 36803 44596 45049 46442 46978 46993 47011 48389 490487.447298006782415e-19 1.4134638842407062e-18https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/728/23?format=asciiUVOpticaldefaultJ/ApJ/728/23/table3*Promising targets to search for HeII (GALEX S/N>3 and (FUV-NUV)<1mag)SimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameObject designationmeta.id;meta.maincharRAJ2000Optical hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Optical degree of declination (J2000)pos.eq.dec;meta.mainzem[2.702/5.037] Emission redshiftsrc.redshiftfloatmag[15.48/24.1] Optical magnitude in Filtmagphot.mag;em.optfloatFiltFilter (BVR, b_J or r) (1)meta.notecharFUVGALEX GR4 FUV (~1350-1780{AA}) AB magnitudemagphot.mag;em.UVfloatNUV? GALEX GR4 NUV (~1770-2830{AA}) AB magnitudemagphot.mag;em.UVfloatnullableLim[0/2] Limit flag on UV detections (2)meta.code.errorintF.S/NSignal-to-noise ration in FUVstat.snrfloatN.S/N? Signal-to-noise ration in NUVstat.snrfloatnullableNf[0/3] Neighbor flag (3)meta.codeintxmCross-match with QSO catalogs (Veron 2010, Syphers 2009)meta.ref.urlintnullableSloanDisplay the online SDSS data for this quasarmeta.ref.urlcharNEDSimbad column added by the CDSmeta.refcharJ/ApJ/728/23/table4*Further quasars with potential FUV flux (GALEX S/N(FUV)>2)SimbadNameSimbad column added by the CDSmeta.idcharNameObject designationmeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Optical hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Optical degree of declination (J2000)pos.eq.dec;meta.mainzem[2.702/5.037] Emission redshiftsrc.redshiftfloatmag[15.48/24.1] Optical magnitude in Filtmagphot.mag;em.optfloatFiltFilter (BVR, b_J or r) (1)meta.notecharFUVGALEX GR4 FUV (~1350-1780{AA}) AB magnitudemagphot.mag;em.UVfloatNUV? GALEX GR4 NUV (~1770-2830{AA}) AB magnitudemagphot.mag;em.UVfloatnullableLim[0/2] Limit flag on UV detections (2)meta.code.errorintF.S/NSignal-to-noise ration in FUVstat.snrfloatN.S/N? Signal-to-noise ration in NUVstat.snrfloatnullableNf[0/3] Neighbor flag (3)meta.codeintxmCross-match with QSO catalogs (Veron 2010, Syphers 2009)meta.ref.urlintnullableSloanDisplay the online SDSS data for this quasarmeta.ref.urlcharNEDSimbad column added by the CDSmeta.refchar