J/ApJ/964/69ivo://CDS.VizieR/J/ApJ/964/69doi:10.26093/cds/vizier/ba-y4-25CDSStorey-Fisher K.Hogg D.W.Rix H.-W.Eilers A.-C.Fabbian G.,Blanton M.R.Alonso D.2026-07-02T12:01:16Z2025-11-06T15:07:12ZCDS support team

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

cds-question@unistra.frquasarsvisible-astronomyspectroscopyinfrared-photometrysurveysredshiftedproper-motionsWe present a new, all-sky quasar catalog, Quaia, that samples the largest comoving volume of any existing spectroscopic quasar sample. The catalog draws on the 6,649,162 quasar candidates identified by the Gaia mission that have redshift estimates from the space observatory's low-resolution blue photometer/red photometer spectra. This initial sample is highly homogeneous and complete, but has low purity, and 18% of even the bright (G<20.0) confirmed quasars have discrepant redshift estimates (|{Delta}z/(1+z)|>0.2) compared to those from the Sloan Digital Sky Survey (SDSS). In this work, we combine the Gaia candidates with unWISE infrared data (based on the Wide-field Infrared Survey Explorer survey) to construct a catalog useful for cosmological and astrophysical quasar studies. We apply cuts based on proper motions and colors, reducing the number of contaminants by approximately four times. We improve the redshifts by training a k-Nearest Neighbor model on SDSS redshifts, and achieve estimates on the G<20.0 sample with only 6% (10%) catastrophic errors with |{Delta}z/(1+z)|>0.2 (0.1), a reduction of approximately three times (approximately two times) compared to the Gaia redshifts. The final catalog has 1,295,502 quasars with G<20.5, and 755,850 candidates in an even cleaner G<20.0 sample, with accompanying rigorous selection function models. We compare Quaia to existing quasar catalogs, showing that its large effective volume makes it a highly competitive sample for cosmological large-scale structure analyses.2024ApJ...964...69Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/964/69CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/363 : The band-merged unWISE Catalog (Schlafly+, 2019)VII/285 : Gaia DR2 quasar and galaxy classification (Bailer-Jones+, 2019)VII/289 : SDSS quasar catalog, sixteenth data release (DR16Q) (Lyke+, 2020)I/356 : Gaia DR3 Part 2. Extra-galactic (Gaia Collaboration, 2022)I/357 : Gaia DR3 Part 3. Non-single stars (Gaia Collaboration, 2022)J/ApJ/778/98 : Cross-correlation of SDSS QSOs and BOSS galaxies (Shen+, 2013)J/ApJ/815/33 : A Hubble diagram for quasars (Risaliti+, 2015)J/AJ/154/269 : A new photo-z method for quasars in Stripe 82 (Yang+, 2017)J/A+A/644/A17 : Astrometrically-selected QSO candidates (Heintz+, 2020)J/A+A/642/A150 : Quasars as standard candles. III. (Lusso+, 2020)J/A+A/668/A99 : Gaia DR3 quasar and galaxy classification (Hughes+, 2022)J/A+A/674/A41 : Composite quasar spectra from Gaia DR3 (Gaia Coll., 2023)J/ApJS/264/9 : Southern phot. QSOs from DES DR2 & NIR surveys (Yang+, 2023)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/964/69https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/964/69http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/964/69https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/964/69https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/964/69http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/964/69GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/964/69/quaiag200 (*Quaia, the Gaia-unWISE G<20.0 Quasar catalog)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/964/69/quaiag200?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/964/69/quaiag200?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/964/69/quaiag200?GETtext/xml+votable180.050000true45.18857530.28242440.0055555555555555560/1-2 4 6 8 1/44-45 47 2/2 8-10 48-49 52-53 58-59 80 82 85 88 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43065 43067-43068 43071 43085 43088 43092-43093 43097 43099 43103 43105 43107-43108 43110-43114 43117-43119 43146 43154 43156-43158 43168-43169 43171 43200 43202-43203 43264 43266 43269 43271 43274-43275 44373-44375 47904 47906-479073.830199579824256e-20 3.916500758235022e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/964/69?format=asciiOpticalInfrareddefaultJ/ApJ/964/69/quaiag200*Quaia, the Gaia-unWISE G<20.0 Quasar catalog_DE.icrsDeclination (ICRS) at Epoch=J2000, proper motions taken into accountdegpos.eq.decindexedrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGaiaDR3Gaia DR3 source identifier (source_id)meta.id;meta.mainindexedobjIDunWISE DR1 objID identifier (unwise_objid)meta.id.crosscharindexedzQuaia[0.086/4.63] Spectroscopic redshift estimate (redshift_quaia)src.redshiftdoublee_zQuaia[0.016/1.9] zQuaia uncertainty (redshift_quaia_err)stat.error;src.redshiftdoubleRA_ICRSRight ascension (ICRS) at Ep=2016.0 (ra)degpos.eq.ra;meta.mainindexedDE_ICRSDeclination (ICRS) at Ep=2016.0 (dec)degpos.eq.dec;meta.mainindexedGLONGalactic longitude (l)degpos.galactic.lonGLATGalactic latitude (b)degpos.galactic.latdoubleGmag[13.88/20] Gaia G-band mean magnitude (phot_g_mean_mag)magphot.mag;stat.mean;em.optfloatBPmag[13.99/21.25] Gaia BP-band mean magnitude (phot_bp_mean_mag)magphot.mag;stat.mean;em.opt.BfloatRPmag[13.46/20.24] Gaia RP-band mean magnitude (phot_rp_mean_mag)magphot.mag;stat.mean;em.opt.RfloatW1mag[8/17.9] WISE W1 (3.4um) band magnitude (mag_w1_vg)magphot.mag;em.IR.3-4umdoubleW2mag[7.4/16.8] WISE W2 (4.6um) band magnitude (mag_w2_vg)magphot.mag;em.IR.4-8umdoublepm[0.0005/4.9] Total proper motion (pm)mas/yrpos.pmdoublepmRA[-3.9/4.6] Proper motion in right ascension direction (pmRA*cosDE) (pmra)mas/yrpos.pm;pos.eq.radoublepmDE[-4.1/3.7] Proper motion in declination direction (pmdec)mas/yrpos.pm;pos.eq.decdoublee_pmRA[0.014/2.2] pmRA uncertainty (pmra_error)mas/yrstat.error;pos.pm;pos.eq.radoublee_pmDE[0.016/2] pmDE uncertainty (pmdec_error)mas/yrstat.error;pos.pm;pos.eq.decdouble_RA.icrsRight ascension (ICRS) at Epoch=J2000, proper motions taken into accountdegpos.eq.raindexed