J/ApJ/925/162ivo://CDS.VizieR/J/ApJ/925/162doi:10.26093/cds/vizier.19250162CDSChen Y.-C.Hwang H.-C.Shen Y.Liu X.Zakamska N.L.Yang Q.Li J.I.2023-12-11T20:14:56Z2023-10-05T08:48:02ZCDS support team

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

cds-question@unistra.frquasarsredshiftedvisible-astronomysurveyshst-photometryultraviolet-astronomyactive-galactic-nucleiDual supermassive black holes (SMBHs) at ~kiloparsec scales are the progenitor population of SMBH mergers and play an important role in understanding the pairing and dynamical evolution of massive black holes in galaxy mergers. Because of the stringent resolution requirement and the apparent rareness of these small-separation pairs, there are scarce observational constraints on this population, with few confirmed dual SMBHs at <10 kpc separations at z>1. Here we present results from a pilot search for kiloparsec-scale dual quasars selected with Gaia Data release 2 (DR2) astrometry and followed up with Hubble Space Telescope (HST) Wide Field Camera 3 dual-band (F475W and F814W) snapshot imaging. Our targets are quasars primarily selected with the varstrometry technique, i.e., light centroid jitter caused by asynchronous variability from both members in an unresolved quasar pair, supplemented by subarcsecond pairs already resolved by Gaia DR2. We find an overall high fraction of HST-resolved pairs among the varstrometry-selected quasars (unresolved in Gaia DR2), ~30%-50%, increasing toward high redshift (~60%-80% at z>1.5). We discuss the nature of the 45 resolved subarcsecond pairs based on HST and supplementary data. A substantial fraction (~40%) of these pairs are likely physical quasar pairs or gravitationally lensed quasars. We also discover a triple quasar candidate and a quadruply lensed quasar, which is among the smallest-separation quadruple lenses. These results provide important guidelines to improve varstrometry selection and follow-up confirmation of ~kiloparsec-scale dual SMBHs at high redshift.2022ApJ...925..162Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/925/162CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/hst : HST Archived Exposures Catalog (STScI, 2007)VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)II/311 : WISE All-Sky Data Release (Cutri+ 2012)II/349 : The Pan-STARRS release 1 (PS1) Survey - DR1 (Chambers+, 2016)VII/286 : SDSS quasar catalog, fourteenth data release (Paris+, 2018)I/345 : Gaia DR2 (Gaia Collaboration, 2018)II/357 : The Dark Energy Survey (DES): Data Release 1 (Abbott+, 2018)I/350 : Gaia EDR3 (Gaia Collaboration, 2020)J/A+AS/116/95 : Magellanic Clouds PNe line intensities (Leisy+, 1996)J/PASP/110/863 : A Stellar Spectral Flux Library: 1150 - 25000 A (Pickles 1998)J/AJ/131/1 : Binary quasars in the SDSS (Hennawi+, 2006)J/ApJ/640/579 : Near-infrared spectra of 27 SDSS quasars (Glikman+, 2006)J/AJ/131/2766 : Quasar luminosity function from SDSS-DR3 (Richards+, 2006)J/AJ/135/496 : SDSS quasar lens search. II. (Inada+, 2008)J/ApJ/705/L76 : AGNs with double-peaked [OIII] lines (Wang+, 2009)J/ApJ/708/427 : Type 2 AGNs with double-peaked [OIII] lines (Liu+, 2010)J/ApJ/716/866 : SDSS search for binary AGN (Smith+, 2010)J/ApJ/719/1672 : SDSS binary quasars at high redshift. I. (Hennawi+, 2010)J/ApJS/194/45 : QSO properties from SDSS-DR7 (Shen+, 2011)J/ApJ/737/101 : AGN pairs from SDSS-DR7. I. (Liu+, 2011)J/ApJ/746/L22 : Dual AGNs in the nearby Universe (Koss+, 2012)J/AJ/143/119 : SDSS Quasar Lens Search. V. Final catalog (Inada+, 2012)J/ApJ/753/156 : T/Y brown dwarfs with WISE photometry (Kirkpatrick+, 2012)J/ApJS/201/23 : Spectroscopy of 88 z<0.7 SDSS QSOs (Eracleous+, 2012)J/AJ/144/125 : Photometry & spectroscopy of Markarian 266 (Mazzarella+, 2012)J/ApJ/789/140 : SDSS quasars balmer emission lines (Liu+, 2014)J/ApJ/799/72 : Binary AGNs from the VLA Stripe 82 survey (Fu+, 2015)J/MNRAS/453/1562 : CRTS close supermassive black hole binaries (Graham+, 2015)J/ApJS/221/12 : AGNs in the MIR using AllWISE data (Secrest+, 2015)J/MNRAS/468/77 : Sample of confirmed quasar pairs (Eftekharzadeh+, 2017)J/AJ/154/269 : A new photo-z method for quasars in Stripe 82 (Yang+, 2017)J/ApJ/888/73 : Varstrometry of SDSS quasars with Gaia DR2 data (Hwang+, 2020)J/ApJS/264/4 : Cand. Double AGNs from Gaia & WISE (CDAGN) (Makarov+, 2023)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/925/162https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/925/162http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/925/162https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/925/162https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/925/162http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/925/162GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/925/162/table2 (*Target properties and log of the HST observations)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/925/162/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/925/162/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/925/162/table2?GETtext/xml+votable180.050000true1.309166770.38033330.0055555555555555566/1525 1528 3771 3843 3850 3988 4651 4773 4798 4825 5063 5076 5583 5643 5717 5740 6264 6577 6593 6981 7211 7373 7391 8197 9559 9637 13474 15146 15608 15931 16078 16220 17143 17747 19087 20624 21369 21445-21446 22645 24568 25651 25711 25713 25894 26424 28358 28977 29390 29399 29703 30090 30894 30950 31566 32710 32972 33294 33636 34185 34497 34900 35140 35999 36040 36442 37385 38085 39226 42935 43215 43544 44574 46343 46362 46488 46598 46895 47186 47220 47641 47938 48278 488141.9867573869263685e-19 3.916500758235022e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/925/162?format=asciiUVOpticaldefaultJ/ApJ/925/162/table2*Target properties and log of the HST observationsf_StdFlag on Std (1)meta.codecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameName of the source (JHHMMSS.ss+DDMMSS.s) (G1)meta.id;meta.maincharprimaryf_Name[m] m: multiple sources in HSTmeta.codecharz[0.1/3.1] Spectroscopic redshift (except flagged)src.redshiftfloatf_z[d] d: photometric redshiftmeta.codecharrmag[17.17/20.1]? SDSS r-band PSF magnitudemagphot.mag;em.opt.RfloatnullableGmag1[16.3/21.1] Gaia G-band magnitude, first valuemagphot.mag;em.optfloatGmag2[17.79/20.83]? Gaia G-band magnitude, second valuemagphot.mag;em.optfloatnullablef_GmagFlag on Gmag (1)meta.codecharepsi1[0/14.3] Gaia astrometric_excess_noise, first valuemasstat.fit.paramfloatepsi2[0/12]? Gaia astrometric_excess_noise, second valuemasstat.fit.paramfloatnullablef_epsiFlag on epsi (1)meta.codecharStd1[12.6/225.1] Standard deviation of Gaia G-band flux, first value (2)e.s**-1stat.stdevfloatStd2[12.8/120.5]? Standard deviation of Gaia G-band flux, second value (2)e.s**-1stat.stdevfloatnullableDateHST observation date (UT)time.epoch;obsnullableExp1[40/1320] HST exposure time in F475W filterstime.duration;obs.exposure;em.opt.BintExp2[40/600] HST exposure time in F814W filterstime.duration;obs.exposure;em.opt.IintCat[1/6] Target category (G2)meta.codeintGaiaDisplay data from Gaia DR2 (I/345) within 1"meta.ref.urlintnullableWISEDisplay data from WISE (II/311) within 1"meta.ref.urlintnullablePS1Display data from PS1 (II/349) within 1"meta.ref.urlintnullableDR16QDisplay the SDSS-DR16 quasar cat. (VII/289) within 1"meta.ref.urlintnullableS15Display data from Secrest+ 2015, J/ApJS/221/12 within 1"meta.ref.urlintnullable_RAPositions from names (right ascension part)degpos.eq.ra;meta.main_DEPositions from names (declination part)degpos.eq.dec;meta.mainJ/ApJ/925/162/table3*Properties of the 45 HST targets with multiple coresNameName of the source (JHHMMSS.ss+DDMMSS.s) (G1)meta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintz[0.1/3.1] Spectroscopic redshift (except flagged)src.redshiftfloatf_z[d] d: photometric redshiftmeta.codecharSep[0.18/0.74]? Angular separationarcsecpos.angDistancefloatnullablerp[1/6.2]? Projected physical separation based on the redshift, r_p_kpcpos.angDistancefloatnullablePA[1.9/333.3]? Position angle between the two brightest sources, east of northdegpos.posAngfloatnullableF475W1[17.58/21.29] HST F475W ST magnitude, source 1magphot.mag;em.opt.BfloatF475W2[18.58/23.87] HST F475W ST magnitude, source 2magphot.mag;em.opt.BfloatF475W3[21.89/24.87]? HST F475W ST magnitude, source 3magphot.mag;em.opt.BfloatnullableF475W4[22.73]? HST F475W ST magnitude, source 4magphot.mag;em.opt.BfloatnullableF814W1[17.55/22.34] HST F814W ST magnitude, source 1magphot.mag;em.opt.IfloatF814W2[18.86/22.44] HST F814W ST magnitude, source 2magphot.mag;em.opt.IfloatF814W3[21.77/24]? HST F814W ST magnitude, source 3magphot.mag;em.opt.IfloatnullableF814W4[22.68]? HST F814W ST magnitude, source 4magphot.mag;em.opt.IfloatnullableCat[1/6] Target category (G1)meta.codeintClassBest-effort classification (1)src.classcharf_ClassFlag(s) on Class (2)meta.codechar