J/ApJ/933/180ivo://CDS.VizieR/J/ApJ/933/180doi:10.26093/cds/vizier.19330180CDSGreen P.J.Pulgarin-Duque L.Anderson S.F.Macleod C.L.Eracleous M.,Ruan J.J.Runnoe J.Graham M.Roulston B.R.Schneider D.P.Ahlf A.,Bizyaev D.Brownstein J.R.Del Casal S.J.Dodd S.A.Hoover D.Matt C.,Merloni A.Pan K.Ramirez A.Ridder M.2023-10-09T11:20:09Z2023-03-29T08:57:06ZCDS support team

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

cds-question@unistra.frquasarsactive-galactic-nucleiredshiftedvisible-astronomyultraviolet-astronomyActive galactic nuclei (AGN) can vary significantly in their rest-frame optical/UV continuum emission, and with strong associated changes in broad line emission, on much shorter timescales than predicted by standard models of accretion disks around supermassive black holes. Most such changing-look or changing-state AGN-and at higher luminosities, changing-look quasars (CLQs)-have been found via spectroscopic follow-up of known quasars showing strong photometric variability. The Time Domain Spectroscopic Survey of the Sloan Digital Sky Survey IV (SDSS-IV) includes repeat spectroscopy of large numbers of previously known quasars, many selected irrespective of photometric variability, and with spectral epochs separated by months to decades. Our visual examination of these repeat spectra for strong broad line variability yielded 61 newly discovered CLQ candidates. We quantitatively compare spectral epochs to measure changes in continuum and H{beta} broad line emission, finding 19 CLQs, of which 15 are newly recognized. The parent sample includes only broad line quasars, so our study tends to find objects that have dimmed, i.e., turn-off CLQs. However, we nevertheless find four turn-on CLQs that meet our criteria, albeit with broad lines in both dim and bright states. We study the response of H{beta} and Mg II emission lines to continuum changes. The Eddington ratios of CLQs are low, and/or their H{beta} broad line width is large relative to the overall quasar population. Repeat quasar spectroscopy in the upcoming SDSS-V black hole Mapper program will reveal significant numbers of CLQs, enhancing our understanding of the frequency and duty cycle of such strong variability, and the physics and dynamics of the phenomenon.2022ApJ...933..180Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/933/180CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)VII/286 : SDSS quasar catalog, fourteenth data release (Paris+, 2018)VII/289 : SDSS quasar catalog, sixteenth data release (DR16Q) (Lyke+, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/933/180https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/933/180http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/933/180https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/933/180https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/933/180http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/933/180GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/933/180/table2 (Changing-look quasars (CLQ) candidates in our visually selected DR14 quasar sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/933/180/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/933/180/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/933/180/table2?GETtext/xml+votable180.050000true5.79608530.58820220.0055555555555555566/4453 4468 4519 4558 4579 4886 4890 4895 4913-4914 5134 5177 5227 5232 5498 5594 5754 5985 9636 9999 10020 10519 10747 10779 11107 11147 11191 11212-11213 11446 17702 17715 17727 17736 17755-17756 17764 17766 17816 17818 17822 17856 18006 18022 18035 18070 18072 18096 18112 18176 18182 18751 18782 18833 18848 19025 19051 19122 28351 28394 28652https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/933/180?format=asciiUVOpticaldefaultJ/ApJ/933/180/table2Changing-look quasars (CLQ) candidates in our visually selected DR14 quasar sampleSimbadNameSimbad column added by the CDSmeta.idcharnullableMJD[51811/58699] Spectrum epoch, JD-2400000.5dtime.epochintFacFacility (2)meta.codecharNsigma[0.5/14.09]? N{sigma}, Broad H{beta}stat.fit.paramfloatnullableStateState (3)physcharL3240[0.46/2075.5] Luminosity, continuum at 3240{AA} (in 10+42 erg/s unit)1e+35Wphys.luminosityfloate_L3240Uncertainty in L32401e+35Wstat.errorfloatL5100[2.5/1673.7] Luminosity, continuum at 5100{AA} (in 10+42 erg/s unit)1e+35Wphys.luminosityfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSDSSSDSS Identifier (JHHMMSS.ss+DDMMSS.ss)meta.id;meta.maincharSelSelection (1)meta.codecharzspec[0.05/0.9] SDSS spectroscopic redshiftsrc.redshiftfloate_L5100[0.1/88.8] Uncertainty in L51001e+35Wstat.errorfloatLHbLuminosity, H{beta} emission (in 10+42 erg/s unit)1e+35Wphys.luminosityfloate_LHbUncertainty in LHb1e+35Wstat.errorfloatL2800[0.77/2224.29]? Luminosity, continuum at 2800{AA} (in 10+42 erg/s unit)1e+35Wphys.luminositydoublenullablee_L2800[0.01/63.52]? Uncertainty in L28001e+35Wstat.errorfloatnullableLMgII[0.05/41.54]? Luminosity, MgII emission (in 10+42 erg/s unit)1e+35Wphys.luminosityfloatnullablee_LMgII[0.05/9.73]? Uncertainty in LMgII1e+35Wstat.errorfloatnullableNotesNotes and/or references (4)meta.notecharQSODR16Display the QSO DR16 data (Lyke et al. 2020, Cat. VII/289)meta.ref.urlcharSloanDisplay the online SDSS data for the nearest objectmeta.ref.urlchar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.main