J/ApJ/854/160ivo://CDS.VizieR/J/ApJ/854/160doi:10.26093/cds/vizier.18540160CDSRumbaugh N.Shen Y.Morganson E.Liu X.Banerji M.McMahon R.G.,Abdalla F.B.Benoit-Levy A.Bertin E.Brooks D.Buckley-Geer E.,Capozzi D.Carnero Rosell A.Carrasco Kind M.Carretero J.Cunha C.E.,D'Andrea C.B.da Costa L.N.DePoy D.L.Desai S.Doel P.Frieman J.,Garcia-Bellido J.Gruen D.Gruendl R.A.Gschwend J.Gutierrez G.,Honscheid K.James D.J.Kuehn K.Kuhlmann S.Kuropatkin N.Lima M.,Maia M.A.G.Marshall J.L.Martini P.Menanteau F.Plazas A.A.Reil K.,Roodman A.Sanchez E.Scarpine V.Schindler R.Schubnell M.Sheldon E.,Smith M.Soares-Santos M.Sobreira F.Suchyta E.Swanson M.E.C.,Walker A.R.Wester W.2019-01-09T14:08:42Z2019-01-03T08:10:09ZCDS support team

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

cds-question@unistra.frquasarssurveysvisible-astronomysloan-photometryredshiftedspectroscopyWe perform a systematic search for long-term extreme variability quasars (EVQs) in the overlapping Sloan Digital Sky Survey and 3 Year Dark Energy Survey imaging, which provide light curves spanning more than 15 years. We identified ~1000 EVQs with a maximum change in g-band magnitude of more than 1 mag over this period, about 10% of all quasars searched. The EVQs have L_bol_~10^45^-10^47^erg/s and L/L_Edd_~0.01-1. Accounting for selection effects, we estimate an intrinsic EVQ fraction of ~30%-50% among all g<~22 quasars over a baseline of ~15yr. We performed detailed multi-wavelength, spectral, and variability analyses for the EVQs and compared them to their parent quasar sample. We found that EVQs are distinct from a control sample of quasars matched in redshift and optical luminosity: (1) their UV broad emission lines have larger equivalent widths; (2) their Eddington ratios are systematically lower; and (3) they are more variable on all timescales. The intrinsic difference in quasar properties for EVQs suggests that internal processes associated with accretion are the main driver for the observed extreme long-term variability. However, despite their different properties, EVQs seem to be in the tail of a continuous distribution of quasar properties, rather than standing out as a distinct population. We speculate that EVQs are normal quasars accreting at relatively low rates, where the accretion flow is more likely to experience instabilities that drive the changes in flux by a factor of a few on multi-year timescales.2018ApJ...854..160Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/854/160CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)VII/279 : SDSS quasar catalog: twelfth data release (Paris+, 2017)VIII/92 : The FIRST Survey Catalog, Version 2014Dec17 (Helfand+ 2015)J/AJ/135/2453 : Sample of BL Lac objects from SDSS and FIRST (Plotkin+, 2008)J/ApJ/699/782 : High-redshift SDSS-DR5 QSOs (Diamond-Stanic+, 2009)J/ApJ/698/895 : Variations in QSOs optical flux (Kelly+, 2009)J/AJ/139/390 : Opt. selected BL Lac objects from SDSS-DR7 (Plotkin+, 2010)J/ApJS/194/45 : QSO properties from SDSS-DR7 (Shen+, 2011)J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)J/ApJ/805/122 : X-ray properties of PHL1811 analogs and WLQs (Luo+, 2015)J/ApJ/817/172 : X-ray Observations of Stripe 82 (LaMassa+, 2016)J/MNRAS/463/296 : PS1 slow-blue nuclear hypervariables (Lawrence+, 2016)J/ApJ/821/33 : Broad H{beta} emission line in 102 Seyfert (Runco+, 2016)J/MNRAS/472/273 : OzDES DR1 (Childress+, 2017)J/AJ/153/107 : Australian Dark Energy Survey (OzDES) QSO catalog (Tie+, 2017)http://www.sdss.org/ : SDSS home pagehttp://www.darkenergysurvey.org/ : DES home pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/854/160https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/854/160http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/854/160https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/854/160https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/854/160http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/854/160GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/854/160/table2 (The "extreme variability quasar" (EVQ) sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/854/160/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/854/160/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/854/160/table2?GETtext/xml+votable180.050000true0.17510111-0.750386110.0055555555555555565/4437 4438 4441 4442 4453 4454 4457 4458 4501 4502 4506 4517 4518 4521 4522 4693 4694 4697 4709 4710 4714 4758 4761 4762 6/0 2 17407 17493 17497 17500 17501 17503 17515 17516 17518 17557 17604 17661 17662 17663 17665 17666 17668 17672 17725 17726 17727 17741 17742 17743 17745 17746 17747 17756 17757 17758 17761 17762 17763 17772 17773 17776 17777 17778 17805 17806 17807 17809 17810 17811 17820 17821 17822 17825 17827 17836 17837 17840 17841 17842 17856 17857 17858 17981 17982 17983 17999 18001 18002 18003 18012 18013 18017 18019 18021 18022 18023 18028 18029 18030 18032 18033 18061 18062 18063 18065 18066 18067 18076 18077 18078 18081 18082 18083 18092 18093 18094 18096 18097 18112 18113 18114 18176 18177 18178 18685 18686 18687 18749 18750 18751 18765 18766 18767 18769 18770 18771 18780 18781 18782 18785 18786 18787 18792 18793 18795 18796 18797 18798 18800 18801 18802 18830 18831 18833 18835 18844 18845 18846 18849 18850 18851 18852 18854 18855 18860 18861 18862 18864 18865 18866 18880 18881 18882 19005 19006 19007 19021 19022 19023 19025 19026 19027 19029 19030 19036 19037 19043 19052 19053 19056 19057 19058 19092 19093 19095 19097 19098 19099 19100 19108 19109 19110 19115 19116 19118 19120 19121 19136 19137 19200 19202 19456 19457 19458 23210 36765 36766 36778 36783 36785 36786 36788 36802 36803 36810 36811 36812 36861 36862 368633.588997330618193e-19 4.653515163505597e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/854/160?format=asciiOpticaldefaultJ/ApJ/854/160/table2The "extreme variability quasar" (EVQ) sampleSpIDSpectroscopic plate-fiber-mjd number from Shen+, 2011, J/ApJS/194/45meta.idcharSimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeq[28/105778] Zero based object index of the DR7 QSO catalog of Shen+ (2011, J/ApJS/194/45)meta.id;meta.mainintRAJ2000Right ascension, decimal degrees (J2000)degpos.eq.ra;meta.mainDEJ2000Declination, decimal degrees (J2000)degpos.eq.dec;meta.mainzspec[0.1/4.4] SDSS spectroscopic redshiftsrc.redshiftfloatMJD-lo[51075/57399.1] Modified Julian Date of faintest epoch, JD-2400000.5 (1)dtime.epochdoublegmag-lo[16.3/23.1] SDSS g PSF AB magnitude at MJD-lomagphot.mag;em.opt.Bfloate_gmag-lo[0.005/0.2] Uncertainty in gmag-lomagstat.errorfloatMJD-hi[51075/57399.1] Modified Julian Date of brightest epoch, JD-2400000.5 (1)dtime.epochdoublegmag-hi[15.2/21.9] SDSS g PSF AB magnitude at MJD-himagphot.mag;em.opt.Bfloate_gmag-hi[0.003/0.2] Uncertainty in gmag-himagstat.errorfloatfFIRST[-1/2]? FIRST quasar type (2)meta.codeintnullableFIRSTDisplay data from FIRST (VIII/92) within 10"meta.ref.urlcharDR7QDisplay data from SDSS-DR7 (VII/260) quasar catalogs within 1"meta.ref.urlcharSloanDisplay the online SDSS data for the nearest objectmeta.ref.urlcharSpInteractive spectrum from SDSS-DR14meta.ref.urlcharNEDNED column added by the CDSmeta.ref.urlchar