J/ApJS/267/36ivo://CDS.VizieR/J/ApJS/267/36doi:10.26093/cds/vizier.22670036CDSZhang X.2025-05-19T20:12:17Z2023-11-30T07:46:16ZCDS support team

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

cds-question@unistra.fractive-galactic-nucleiredshiftedvisible-astronomyspectroscopyphotometrysurveysThe main objective of this article, the first in a dedicated series, is to report basic results on systematic research of low-redshift optically selected SDSS Type 2 active galactic nuclei (AGNs) but with apparent optical variabilities. For all the pipeline-classified Type 2 AGNs in SDSS DR16 with z<0.3 and signal-to-noise ratio >10, long-term optical V-band light curves are collected from the Catalina Sky Survey. Through all light curves described by a damped random walk process with process parameters of {sigma}/(mag/days^0.5^) and {tau}/days, 156 Type 2 AGNs have apparent variabilities with process parameters at least 3 times larger than corresponding uncertainties and with ln({sigma}/(mag/days^0.5^)){>}-4, indicating central AGN activity regions directly in the line of sight, leading the 156 Type 2 AGNs as misclassified Type 2 AGNs. Furthermore, based on spectroscopic emission features around H{alpha}, 31 out of the 156 AGNs have broad H{alpha}, indicating the 31 Type 2 AGNs are actually Type 1.8 and/or 1.9 AGNs. Meanwhile, 14 out of the 156 AGNs have multiepoch SDSS spectra. After checking multiepoch spectra of the 14 objects, no clues for appearance and/or disappearance of broad lines indicates true Type 2 AGNs rather than changing-look AGNs are preferred in the collected Type 2 AGNs with long-term variabilities. Moreover, a small sample of Type 2 AGNs have long-term variabilities with features roughly described by theoretical tidal disruption events (TDEs) expected t^-5/3^, indicating probable central TDEs as further and strong evidence to support true Type 2 AGNs.2023ApJS..267...36Zhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/267/36CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)J/ApJ/696/870 : Catalina Real-time Transient Survey (CRTS) (Drake+, 2009)J/ApJ/698/895 : Variations in QSOs optical flux (Kelly+, 2009)J/MNRAS/441/1186 : Cataclysmic variables from CRTS (Drake+, 2014)J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)J/MNRAS/438/557 : BLR-less AGNs in Stripe82 (Zhang, 2014)J/ApJS/219/1 : Catalog of Type-1 AGNs from SDSS-DR7 (Oh+, 2015)J/MNRAS/455/2918 : Phot. & line luminosities for ASASSN-14li (Holoien+, 2016)J/ApJS/229/39 : Narrow line Seyfert 1 gal. from SDSS-DR12 (Rakshit+, 2017)J/ApJ/878/11 : Type 1 vs 2 X-ray COSMOS AGNs & environment (Zou+, 2019)J/ApJ/896/10 : NSA low-mass gal. with PTF obs. (Baldassare+, 2020)J/MNRAS/499/6053 : Indiv. opt. var. of AGNs from MEXSAS2 (Laurenti+, 2020)J/ApJ/933/180 : TDSS. Changing-look quasars candidates (Green+, 2022)http://nesssi.cacr.caltech.edu/DataRelease/ : The Catalina Surveys DR2 homehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/267/36https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/267/36http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/267/36https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/267/36https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/267/36http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/267/36GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/267/36/varagn (Basic information (Table 1) and line parameters (Table 2) of the 156 Type-2 AGN with apparent long-term variabilities)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/267/36/varagn?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/267/36/varagn?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/267/36/varagn?GETtext/xml+votable180.050000true153.664583-0.8308890.0055555555555555566/4106 4257 4263 4283 4306 4316 4353 4438 4447 4517 4549 4569 4621 4632 4634 4641 4661 4668 4676 4751 4790 4795-4796 4804 4838 4843 4874 4906 4990 5034 5042 5061 5113 5122 5131 5153 5213 5216 5329 5335 5491 5508 5532 5572 5645 5653 5680 5688 5796 6212 6436 6458 6531 6654 6741 6912 7277 7301 8207 8236 8258 8282 8285 8511 8526 8530 8751 8785 8816 8854 9088 9118 9170 9175 9277 9287 9338 9421 9469 9609 9784 9883 10560 10937 17237 17828 18003 18084 18405 18583 18687 18853 18864 18880 19029 19989 20005 21877 22355-22356 22365 23060 23204 25910 25951 25955 25958 25987 25999 26051 26071 26255 26507 26575 26961 26965 26969 27106 27109 27224 27259 27333 27354 27404 27416 27453 27465 27483 27539 27557 28183 28208 28313 28320 28391 28421 28471 28538 30037 30039 31383 31398 31407 31433 31475 31632 31653 32408 32426 32491 32500 368613.588997330618193e-19 4.653515163505597e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/267/36?format=asciiOpticaldefaultJ/ApJS/267/36/varagnBasic information (Table 1) and line parameters (Table 2) of the 156 Type-2 AGN with apparent long-term variabilitiesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSp-IDSDSS DR16 plate-mjd-fiberid identifiermeta.id;meta.maincharzspec[0/0.4] SDSS DR16 spectroscopic redshiftsrc.redshiftfloatNameSDSS DR16 coordinate based name (Jhhmmss.s+/-ddmmss.s) (G1)meta.idcharm1[11.5/18.5] Mean photometric magnitude of the CSS light curvemagphot.mag;em.optfloatm2[13.2/25.2] SDSS DR16 photometric g-band Petrosian magnitudemagphot.mag;em.opt.BfloatlogLO3[0/42.1] log, [OIII] luminosity, erg/slog(1e-07W)phys.luminosityfloate_logLO3[0.01/0.2] Uncertainty in logLO3log(1e-07W)stat.errorfloatlogO3HB[-0.53/1.4] log, Flux [OIII]5006{AA} relative to Flux H{beta}phot.flux;arith.ratiofloate_logO3HB[0.01/0.851] Uncertainty in logO3HBstat.errorfloatlogN2HA[-0.41/0.44] log, Flux [NII]6583{AA} relative to Flux H{alpha}phot.flux;arith.ratiofloate_logN2HA[0.006/0.4] Uncertainty in logN2HAstat.errorfloatlnsigma[-3.7/-0.97] natural log, {sigma}/mag/sqrt(day)stat.fit.paramfloate_lnsigma[0.09/0.6] Uncertainty in lnsigmastat.errorfloatlntau[2.8/7.2] natural log, {tau}/daylog(d**-1)stat.fit.paramfloate_lntau[0.12/1.5] Uncertainty in lntaulog(d**-1)stat.errorfloatf_Sp-IDFlag on Sp-ID (1)meta.codecharsig-NII1[1.2/6.1] Second moment, first component, [NII]6583{AA}, Angstroms0.1nmspect.line.widthfloate_sig-NII1[0.01/1.3] Uncertainty in sig-NII10.1nmstat.errorfloatflux-NII1[11/4012] Flux, first component, [NII]6583{AA}, 10^-17^erg/s/cm21e-20W.m**-2phot.fluxinte_flux-NII1[1/191] Uncertainty in flux-NII11e-20W.m**-2stat.errorintsig-NII2[2.36/11]? Second moment, second component, [NII]6583{AA}, Angstroms (2)0.1nmspect.line.widthfloatnullablee_sig-NII2[0/2]? Uncertainty in sig-NII2 (2)0.1nmstat.errorfloatnullableflux-NII2[36/1488]? Flux, second component, [NII]6583{AA}, 10^-17^erg/s/cm2 (2)1e-20W.m**-2phot.fluxintnullablee_flux-NII2[8/147]? Uncertainty in flux-NII2 (2)1e-20W.m**-2stat.errorintnullablesig-Ha1[1.38/9.1] Second moment, first component, H{alpha}, Angstroms0.1nmspect.line.widthfloate_sig-Ha1[0.02/2.4] Uncertainty in sig-Ha10.1nmstat.errorfloatflux-Ha1[10/3751] Flux, first component, H{alpha}, 10^-17^erg/s/cm21e-20W.m**-2phot.fluxinte_flux-Ha1[1/150] Uncertainty in flux-Ha11e-20W.m**-2stat.errorintsig-Ha2[1.4/103]? Second moment, second component, H{alpha}, Angstroms (2)0.1nmspect.line.widthfloatnullablee_sig-Ha2[0.07/9]? Uncertainty in sig-Ha2 (2)0.1nmstat.errorfloatnullableflux-Ha2[37/4705]? Flux, second component, H{alpha}, 10^-17^erg/s/cm2 (2)1e-20W.m**-2phot.fluxintnullablee_flux-Ha2[4/391]? Uncertainty in flux-Ha2 (2)1e-20W.m**-2stat.errorintnullablechi2[0.28/4.1] Determined {chi}^2^ (3)stat.fit.chi2floatbHaBroad H{alpha} components?meta.codecharSpInteractive spectrum from SDSS-DR16meta.ref.urlchar_RAPositions from SDSS-DR16 names (right ascension part)degpos.eq.ra;meta.main_DEPositions from SDSS-DR16 names (declination part)degpos.eq.dec;meta.mainSimbadNameSimbad column added by the CDSmeta.idcharnullable