J/ApJS/282/28ivo://CDS.VizieR/J/ApJS/282/28CDSChen Z.-Q.Jin J.-J.Guo W.-J.Sun S.-X.Pan Z.-W.Liu C.-X.,Cheng H.-Q.Hu J.-W.Sheng Z.-F.Zou HuChen Z.-B.Zheng Qi,Yuan Q.-R.2026-08-26T09:10:23Z2026-08-26T09:58:23ZCDS support team

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

cds-question@unistra.fractive-galactic-nucleivisible-astronomyspectroscopyline-intensitiesredshiftedquasarsblack-holesradio-sourcesWe present a systematic search for changing-look (CL) quasars at high redshift z>0.9 by crossmatching the spectroscopic data sets from the Dark Energy Spectroscopic Instrument Data Release 1 and Sloan Digital Sky Survey Data Release 18. We identify 97 CL quasars showing significant variability in high-ionization broad emission lines, including 45 turn-on and 52 turn-off events, corresponding to a detection rate of ~0.042%. The low rate relative to low-ionization CL quasar searches is likely due to selection and physical effects in high-ionization lines. Based on the CL quasar sample, we find that CL quasars generally exhibit lower accretion rates compared to typical quasars, with average Eddington ratios of log{lambda}_Edd_~-1.14 in the bright state and ~-1.39 in the dim state, compared to ~-0.65 for typical quasars. Furthermore, while high-ionization lines in CL quasars follow the Baldwin effect on a population level, some sources can display inverse Baldwin trends. In addition, we find a positive correlation between the variability in high-ionization lines (e.g., MgII, CIII]) and the change in bolometric luminosity. We also estimate a characteristic rest-frame timescale of ~3yr for CL transitions, with no significant difference between turn-on and turn-off cases. Taken as a whole, these findings support an accretion-driven origin of the CL phenomenon, and provide new insights into the variability of high-ionization emission lines.2026ApJS..282...28Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/282/28CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVIII/92 : The FIRST Survey Catalog, Version 2014Dec17 (Helfand+ 2015)V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)V/161 : DESI DR1 redshift catalog (DESI Col.+ 2025)J/ApJS/166/470 : SDSS-Spitzer type I QSOs IR photometry (Richards+, 2006)J/ApJ/696/870 : Catalina Real-time Transient Survey (CRTS) (Drake+, 2009)J/ApJ/702/767 : CIV and FeK{alpha} Baldwin effects in AGNs (Wu+, 2009)J/ApJS/194/45 : QSO properties from SDSS-DR7 (Shen+, 2011)J/ApJ/733/60 : Accretion rate of AGNs from COSMOS surveys (Trump+, 2011)J/ApJ/750/99 : The Pan-STARRS1 photometric system (Tonry+, 2012)J/ApJ/777/168 : CIV and SiIV broad abs. line troughs in SDSS (Filiz+, 2013)J/ApJS/216/4 : SDSS-RM project: technical overview (Shen+, 2015)J/ApJ/874/8 : Follow-up sp. of SDSS changing-look QSOs (Macleod+, 2019)J/ApJS/241/34 : The SDSS Reverberation Mapping (SDSS-RM) project (Shen+, 2019)J/ApJ/883/94 : Optical and UV follow-up of 1ES 1927+654 (Trakhtenbrot+, 2019)J/ApJ/905/52 : Extreme variability QSOs from SDSS DR16 (Guo+, 2020)J/ApJS/249/17 : SDSS QSO DR14 spectral properties (Rakshit+, 2020)J/ApJ/933/180 : TDSS. Changing-look quasars candidates (Green+, 2022)J/ApJS/272/13 : Changing-look AGN. I. Main sequence transition (Panda+, 2024)J/ApJS/278/28 : CL-AGN from DESI. II. Stat. properties from DR1 (Guo+, 2025)http://www.sdss.org/dr18/ : SDSS DR18 homepagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/282/28https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/282/28http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/282/28https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/282/28https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/282/28http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/282/28GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/282/28/table3 (Catalog of changing-look (CL) quasars in this work)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/282/28/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/282/28/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/282/28/table3?GETtext/xml+votable180.050000true7.4945355.834533060.005555555555555556Cone search capability for table J/ApJS/282/28/table5 (CL quasar candidates identified in this work)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/282/28/table5?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/282/28/table5?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/282/28/table5?GETtext/xml+votable180.050000true2.286230.6260.0055555555555555565/2856 6/33 2061 2115 2568 4111 4153 4176 4212 4245 4398 4477 4683 4771 4775 4852 4860-4861 4986 5030 5062 5072 5099 5265 5269 5351 5415 5439 5534 5625 5643 5728 5739 5792 5930 6258 6260 6343 6464 6482 6486 6509 6556 6594 6603 8283 8300 8306 8474 8506 8530 9059 9107 9163 9182 9303 9324 9331 9333 9336 9342 9383 9463 9608 9619 9735 9745 9756 9767 9784 9839 9870 9987 10010 10042 10044 10155 10436 10443 10466 10469-10470 10511 10549 10561 10579 10629 10779 10782 10876 10894 10960 10965 11024 11118 11158 11167 11202 11209 11233 11402 11406 11428 11430 13351 17659 17663 17689 17695 17717 17743 17745 17754-17756 17759 17763-17766 17769-17770 17772-17773 17776 17825 17832 17838 17843 17864 17873 17890 17996 18009-18010 18016 18020-18021 18067 18072-18073 18113 18123 18158 18162-18163 18170 18176 18178 18184 18188 18208 18226 18294-18295 18299-18300 18310 18337 18390-18391 18394 18420 18424 18775 18778 18789 18795 18797-18798 18801 18831 18866 18999 19007 19093 19250 19466 19523 19596 19789 19802 19915 20129 20141 20160 20186 20215 20272 20332 23186-23187 25953 25999 26069 26167 26206 26509 26943 26953 26965 27297 27388 27547 27614 27657 27661 27713 27876 28402 28626 32417 36808 36835 409499.276497240453405e-25 9.276497240453405e-25https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/282/28?format=asciiOpticalRadiodefaultJ/ApJS/282/28/table3Catalog of changing-look (CL) quasars in this workrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintz[0.9/3.3] Spectroscopic redshiftsrc.redshiftfloatEWCIV-d[10/163]? Equivalent Width of C IV in dim state0.1nmspect.line.eqWidthfloatnullablee_EWCIV-d[1/19]? Uncertainty in EWCIV-d (1)0.1nmstat.error;spect.line.eqWidthfloatnullableFWHMMgII-b[2841/10565]? FWHM of Mg II in bright statekm/sspect.line.widthintnullableRAJ2000[7.4/360] Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000[-7.7/56.4] Declination (J2000)degpos.eq.dec;meta.mainMJD-SDSS[52591/59304] Modified Julian Date of SDSS spectrumdtime.epochintMJD-DESI[59251.96/59737.3] Mean MJD of the coadded DESI spectradtime.epoch;stat.meandoubleTransChanging state between SDSS and DESI spectrameta.codecharMgIIState change in Mg IImeta.codecharCIIIState change in C IIImeta.codecharCIVState change in C IVmeta.codecharSiIVState change in Si IVmeta.codecharLyaState change in Ly{alpha}meta.codecharlogLBol-b[45.17/46.73] Log bolometric luminosity in bright state; erg/slog(1e-07W)phys.luminosity;phot.flux.bolfloate_logLBol-b[0/0.1] Uncertainty in logLBol-b (1)log(1e-07W)stat.error;phys.luminosity;phot.flux.bolfloatlogLBol-d[45/46.53] Log bolometric luminosity in dim state; erg/slog(1e-07W)phys.luminosity;phot.flux.bolfloate_logLBol-d[0/0.3] Uncertainty in logLBol-d (1)log(1e-07W)stat.error;phys.luminosity;phot.flux.bolfloatEWMgII-b[4/157]? Equivalent Width of Mg II in bright state0.1nmspect.line.eqWidthfloatnullablee_EWMgII-b[1/9]? Uncertainty in EWMgII-b (1)0.1nmstat.error;spect.line.eqWidthfloatnullableEWMgII-d[9/138]? Equivalent Width of Mg II in dim state0.1nmspect.line.eqWidthfloatnullablee_EWMgII-d[0.8/20]? Uncertainty in EWMgII-d (1)0.1nmstat.error;spect.line.eqWidthfloatnullableEWCIII-b[24.8/122]? Equivalent Width of CIII] in bright state0.1nmspect.line.eqWidthfloatnullablee_EWCIII-b[0.6/11]? Uncertainty in EWCIII-b (1)0.1nmstat.error;spect.line.eqWidthfloatnullableEWCIII-d[1.8/80]? Equivalent Width of CIII] in dim state0.1nmspect.line.eqWidthfloatnullablee_EWCIII-d[0.7/18]? Uncertainty in EWCIII-d (1)0.1nmstat.error;spect.line.eqWidthfloatnullableEWCIV-b[27/237]? Equivalent Width of C IV in bright state0.1nmspect.line.eqWidthfloatnullablee_EWCIV-b[1/15]? Uncertainty in EWCIV-b (1)0.1nmstat.error;spect.line.eqWidthfloatnullablee_FWHMMgII-b[133/3541]? Uncertainty in FWHMMgII-b (1)km/sstat.error;spect.line.widthintnullableFWHMMgII-d[2816/12919]? FWHM of Mg II in dim statekm/sspect.line.widthintnullablee_FWHMMgII-d[159/3921]? Uncertainty in FWHMMgII-d (1)km/sstat.error;spect.line.widthintnullableFWHMCIV-b[3403/23339]? FWHM of C IV in bright statekm/sspect.line.widthintnullablee_FWHMCIV-b[120/8931]? Uncertainty in FWHMCIV-b (1)km/sstat.error;spect.line.widthintnullableFWHMCIV-d[2820/12755]? FWHM of C IV in dim statekm/sspect.line.widthintnullablee_FWHMCIV-d[0/11496]? Uncertainty in FWHMCIV-d (1)km/sstat.error;spect.line.widthintnullableFMgII-b[12/787]? Flux of Mg II in bright state; 10^-17^erg/s/cm^2^1e-20W.m**-2phot.flux;spect.linefloatnullablee_FMgII-b[3.9/28]? Uncertainty in FMgII-b (1)1e-20W.m**-2stat.error;phot.flux;spect.linefloatnullableFMgII-d[15/532]? Flux of Mg II in dim state; 10^-17^erg/s/cm^2^1e-20W.m**-2phot.flux;spect.linefloatnullablee_FMgII-d[1.7/38]? Uncertainty in FMgII-d (1)1e-20W.m**-2stat.error;phot.flux;spect.linefloatnullableFCIII-b[68/700]? Flux of C III] in bright state; 10^-17^erg/s/cm^2^1e-20W.m**-2phot.flux;spect.linefloatnullablee_FCIII-b[5/32]? Uncertainty in FCIII-b (1)1e-20W.m**-2stat.error;phot.flux;spect.linefloatnullableFCIII-d[2/346]? Flux of C III] in dim state; 10^-17^erg/s/cm^2^1e-20W.m**-2phot.flux;spect.linefloatnullablee_FCIII-d[3.6/38]? Uncertainty in FCIII-d (1)1e-20W.m**-2stat.error;phot.flux;spect.linefloatnullableFCIV-b[121/1350]? Flux of C IV in bright state; 10^-17^erg/s/cm^2^1e-20W.m**-2phot.flux;spect.linefloatnullablee_FCIV-b[9/72]? Uncertainty in FCIV-b (1)1e-20W.m**-2stat.error;phot.flux;spect.linefloatnullableFCIV-d[27/709]? Flux of C IV in dim state; 10^-17^erg/s/cm^2^1e-20W.m**-2phot.flux;spect.linefloatnullablee_FCIV-d[4/34]? Uncertainty in FCIV-d (1)1e-20W.m**-2stat.error;phot.flux;spect.linefloatnullablelogMBH[8.3/10.3] Log adopted fiducial black hole masslog(solMass)phys.massfloate_logMBH[0.02/0.4] Uncertainty in LogMBH (1)log(solMass)stat.error;phys.massfloatlogREdd-b[-2.2/-0.29] Logarithmic Eddington ratio in bright statephys.luminosity;arith.ratiofloate_logREdd-b[0/0.1] Uncertainty in logREdd-b (1)stat.error;phys.luminosity;arith.ratiofloatlogREdd-d[-2.6/-0.51] Logarithmic Eddington ratio in dim statephys.luminosity;arith.ratiofloate_logREdd-d[0/0.05] Uncertainty in logREdd-d (1)stat.error;phys.luminosity;arith.ratiofloatF1.4GHz[1.7/5.4]? FIRST catalog 1.4GHz radio fluxmJyphot.flux.density;em.radio.750-1500MHzdoublenullableDESIDisplay data from DESI DR1 zcat (V/161) within 3"meta.ref.urlnullableSloanDisplay the online SDSS-DR19 data for the nearest objectmeta.ref.urlcharSDSSUnique identifier of SDSS object (JHHMMSS.ss+DDMMSS.s)meta.id;meta.maincharJ/ApJS/282/28/table5CL quasar candidates identified in this workDEJ2000[-2.7/58.7] Declination (J2000)degpos.eq.dec;meta.mainz[0.94/3.64] Spectroscopic redshiftsrc.redshiftfloatMJD-SDSS[51816/59292] Modified Julian Date of SDSS spectrumdtime.epochintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSDSSUnique identifier of SDSS object (JHHMMSS.ss+DDMMSS.s)meta.id;meta.maincharRAJ2000[2.2/358] Right Ascension (J2000)degpos.eq.ra;meta.mainMJD-DESI[59253.33/59729.37] Mean MJD of the coadded DESI spectradtime.epoch;stat.meandoubleTransChanging state between SDSS and DESI spectrameta.codecharDESIDisplay data from DESI DR1 zcat (V/161) within 3"meta.ref.urlnullableSloanDisplay the online SDSS-DR19 data for the nearest objectmeta.ref.urlchar