J/A+A/693/A35ivo://CDS.VizieR/J/A+A/693/A35doi:10.26093/cds/vizier.36930035CDSJana A.Ricci C.Temple M.J.Chang H.-K.Shablovinskaya E.,Trakhtenbrot B.Diaz Y.Ilic D.Nandi P.Koss M.2025-03-03T20:01:39Z2025-01-03T13:53:32ZCDS support team

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

cds-question@unistra.fractive-galactic-nucleispectroscopyvisible-astronomyultraviolet-astronomyx-ray-sourcesChanging-look active galactic nuclei (CLAGNs) show the appearance and disappearance of broad emission lines in their UV/optical spectra on timescales of months to decades. Here, We investigate how Changing-look (CL) transitions depend on several AGN parameters such as accretion rate, obscuration properties and black hole mass. We study a sample of 20 nearby optically-identified CLAGNs from the BAT AGN Spectroscopic Survey (BASS), using quasi-simultaneous optical and X-ray observations taken in the last ~40 years. We find that for all CLAGNs, the transition is accompanied by a change in Eddington ratio. The CL transitions are not associated with changes in the obscuration properties of the AGN. CLAGNs are found to have a median Eddington ratio lower than the AGNs in the BASS sample in which CL transitions were not detected. The median of the transition Eddington ratio (Eddington ratio at which AGN changes its state) is found to be ~0.01 for type 1 <-> 1.8/1.9/2 transition, which is consistent with the hard <-> soft state transition in black hole X-ray binaries. Most CL events are constrained to occur within 3-4 years, which is considerably shorter than the expected viscous timescale in AGN accretion disk. The transitions of the optical CLAGNs studied here are likely associated to state changes in the accretion flow, possibly driven by disk-instability.2025A&A...693A..35Jhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/693/A35CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/693/A35https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/693/A35http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/693/A35https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/693/A35https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/693/A35http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/693/A35GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/693/A35/table1 (List of CLAGNs)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/693/A35/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/693/A35/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/693/A35/table1?GETtext/xml+votable180.050000true20.973-35.060.0055555555555555566/4378 7642 7921 8922 10454 10912 16301 17727 17814 18794 21824 25153 29795 31401 33958 34531 34881 35623 46399 46533https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/693/A35?format=asciiX-rayUVOpticaldefaultJ/A+A/693/A35/table1List of CLAGNsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNoSequential numbermeta.recordintNameCluster namemeta.id;meta.maincharBATBAT IDmeta.idintRAJ2000right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Decliination (J2000)degpos.eq.dec;meta.mainzRedshiftsrc.redshiftfloatlogMBHMass of the black holelog(solMass)phys.massfloate_logMBH? Mass of the black hole errorlog(solMass)stat.errorfloatnullabler_logMBH[1/3] References for black hole mass (1)meta.ref;pos.frameintCLTransInformation of the optical spectral statesmeta.notecharJ/A+A/693/A35/tablecInformation of optical and X-ray observations for the 20 clusters (tables C1-C20)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameCluster namemeta.id;meta.maincharObs.dateUT observation datetime.epoch;obsnullableBroadHb[YN-] Broad Hbeta Y = present, N = absentmeta.codecharBroadHa[YN-] Broad Halpha Y = present, N = absentmeta.codecharType? Optical spectral statesrc.spTypefloatnullableTelOOptical Telescope (1)meta.id;instr.telcharlogLbol? Bolometric luminosity (erg/s)log(1e-07W)phys.luminosityfloatnullablee_logLbol? Error of Lbol (erg/s)log(1e-07W)stat.errorfloatnullableEddratio? Eddington ratiophys.luminosity;arith.ratiofloatnullablee_Eddratio? Error of Eddington ratiostat.errorfloatnullablelogNH? Hydrogen column densitylog(cm**-2)phys.columnDensityfloatnullablee_logNH? Error of N_Hlog(cm**-2)stat.errorfloatnullableTelXX-ray telescope (2)meta.id;instr.telcharRefsReferences, in refs.dat filemeta.ref;pos.framecharl_tCLLimit flag on tCLmeta.code.errorchartCL? CL Transition timedtime.intervalintnullableJ/A+A/693/A35/refsReferencesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRefReference codemeta.notecharAutAuthor's namemeta.bib.authorcharBibCodeBibCodemeta.bib.bibcodecharComCommentsmeta.notechar