J/ApJS/278/28 CL-AGN from the DESI. II. Stat. properties from DR1 (Guo+, 2025) ================================================================================ Changing-Look Active Galactic Nuclei from the Dark Energy Spectroscopic Instrument. II. Statistical properties from the first Data Release. Guo W.-J., Zou Hu, Greenwell C.L., Alexander D.M., Fawcett V.A., Pan Z., Siudek M., Aguilar J.N., Ahlen S., Brooks D., Claybaugh T., Dawson K., de la Macorra A., Doel P., Font-Ribera A., Gaztanaga E., Gontcho Gontcho S. A, Gutierrez G., Kehoe R., Kisner T., Landriau M., Le Guillou L., Manera M., Meisner A., Miquel R., Moustakas J., Prada F., Rossi G., Sanchez E., Schubnell M., Sprayberry D., Sui J., Tarle G., Weaver B.A., Xiao Y.-A., Zou S. =2025ApJS..278...28G ================================================================================ ADC_Keywords: Active gal. nuclei; Spectra, optical; Redshifts; Black holes Keywords: Active galactic nuclei ; Active galaxies ; Accretion ; Supermassive black holes ; Catalogs Abstract: We present the identification of changing-look active galactic nuclei (CL-AGNs) from the Dark Energy Spectroscopic Instrument First Data Release and Sloan Digital Sky Survey Data Release 16 at z<=0.9. To confirm the CL-AGNs, we utilize spectral flux calibration assessment via an [OIII]-based calibration, pseudophotometry examination, and visual inspection. This rigorous selection process allows us to compile a statistical catalog of 561 CL-AGNs, encompassing 527 H{beta}, 149 H{alpha}, and 129 MgII CL behaviors. In this sample, we find (1) a 283:278 ratio of turn-on to turn-off CL-AGNs. (2) The median Eddington ratio for CL-AGNs in the dim state is approximately {lambda}Edd~0.01. (3) A strong correlation between the change in the luminosity of the broad emission lines (BELs) and variation in the continuum luminosity, with MgII and H{beta} displaying similar responses during CL phases. (4) The Baldwin-Phillips-Terlevich diagram for CL-AGNs shows no statistical difference from the general AGN catalog. (5) Five CL-AGNs are associated with asymmetrical mid-infrared flares, possibly linked to tidal disruption events. Given the large CL-AGN sample and the stochastic sampling of spectra, we propose that some CL phenomena are inherently due to typical AGN variability during low accretion rates, particularly for CL phenomenon only occurring on one BEL. Finally, we introduce a monotonically dimming CL phase for objects characterized by a gradual decline over decades in the light curve and the complete disappearance of entire BELs in faint spectra, indicative of a real transition in the accretion disk. Description: We construct the parent sample from the Dark Energy Spectroscopic Instrument (DESI) First Data Release (DR1) and SDSS DR16/DR16Q catalogs. See Section 3.1. Throughout the study, we adopt a {Lambda}CDM cosmology with H0=67km/s/Mpc, {Omega}_{Lambda}_=0.68, and {Omega}_m_=0.32. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file spdesi.dat 198 561 Metadata for DESI spectra used and the luminosities and masses derived spsdss.dat 194 561 Metadata for SDSS spectra used and the luminosities and masses derived -------------------------------------------------------------------------------- See also: V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020) VII/289 : SDSS quasar catalog, sixteenth data release (DR16Q) (Lyke+, 2020) VII/292 : DESI Legacy Imaging Surveys DR8 photometric redshifts (Duncan, 2022) V/161 : DESI DR1 redshift catalog (DESI Col.+ 2025) J/ApJS/132/37 : Spectroscopy of Southern warm IR galaxies (Kewley+, 2001) J/ApJ/680/169 : SDSS DR5 virial black hole masses (Shen+, 2008) J/ApJ/696/870 : Catalina Real-time Transient Survey (CRTS) (Drake+, 2009) J/ApJ/698/895 : Variations in QSOs optical flux (Kelly+, 2009) J/ApJ/716/30 : SED of Fermi bright blazars (Abdo+, 2010) J/ApJ/733/60 : Accretion rate of AGNs from COSMOS surveys (Trump+, 2011) J/MNRAS/426/2703 : Type 1 AGN at low z. II. (Stern+, 2012) J/ApJ/792/30 : NEOWISE magnitudes for near-Earth objects (Mainzer+, 2014) J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014) J/ApJ/869/142 : Monitoring AGNs with Hbeta Asymmetry (MAHA). I. (Du+, 2018) J/ApJ/877/23 : SEAMBHs. X. Reverberation mapping campaign (Lu+, 2019) J/ApJ/874/8 : Follow-up sp. of SDSS changing-look QSOs (Macleod+, 2019) J/ApJ/887/15 : Xinglong sp. of two changing-look SDSS AGNs (Wang+, 2019) J/MNRAS/491/4925 : Changing-state quasars with CRTS (Graham+, 2020) J/ApJ/905/52 : Extreme variability QSOs from SDSS DR16 (Guo+, 2020) J/ApJ/901/55 : SDSS-RM project: MgII lags (Homayouni+, 2020) J/ApJS/249/17 : SDSS QSO DR14 spectral properties (Rakshit+, 2020) J/ApJS/252/32 : MIR outbursts in SDSS gal. (MIRONG). I. (Jiang+, 2021) J/ApJ/933/180 : TDSS. Changing-look quasars candidates (Green+, 2022) J/MNRAS/514/164 : Opt. variability of 190 Quasars in S82 region (Stone+, 2022) Byte-by-byte Description of file: spdesi.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 19 I19 --- TargetID DESI target identifier (TARGETID) 21- 29 F9.5 deg RAdeg Right Ascension, DESI (J2000) (RA) 31- 39 F9.5 deg DEdeg [-10.1/68] Declination, DESI (J2000) (Dec) 41- 47 F7.5 --- zspec [0.059/0.9] Spectroscopic redshift from DESI (Redshift) 49- 55 A7 --- Survey Survey ID (SURVEY) (1) 57- 62 A6 --- Prog DESI program ID (PROGRAM) 64- 68 I5 --- Healpix [34/49105] HEALPIX pixel ID (HEALPIX) 70- 74 I5 d MJD [51578/58514] Mean modified Julian Data of coadded spectra (MJD) 76- 83 F8.5 [10-7W] logL5100 [40.3/45.2] Log, Continuum luminosity at 5100{AA} (LOG_L5100) 85- 93 F9.5 [10-7W] e_logL5100 [0.0028/146.5] Uncertainty in logL5100 (LOG_L5100_ERR) 95- 102 F8.5 [10-7W] logL2500 [40/45.5] Log, Extrapolated luminosity at 2500{AA} (LOG_L2500) 104- 112 F9.5 [10-7W] e_logL2500 [0.0028/146.5] Uncertainty in logL2500 (LOG_L2500_ERR) 114- 121 F8.5 [10-7W] logLMgII [39.6/43.7]? Log, broad MgII line luminosity (LOG_LMgII) 123- 129 F7.5 [10-7W] e_logLMgII [0.028/3]? Uncertainty in logLMgII (LOG_LMgII_ERR) 131- 138 F8.5 [10-7W] logLHb [36.3/43.4] Log, broad H{beta} line luminosity (LOG_LHB) 140- 147 F8.6 [10-7W] e_logLHb [0/3] Uncertainty in logLHb (LOG_LHB_ERR) 149- 156 F8.5 [10-7W] logLHa [39.29/43.3]? Log, broad H{alpha} line luminosity (LOG_LHA) 158- 165 F8.6 [10-7W] e_logLHa [0/2.6]? Uncertainty in logLHa (LOG_LHA_ERR) 167- 173 F7.5 [Msun] logMBH-Hb [6.49/9.51]? Log, black hole mass from H{beta} (LOG_MBH_HB) 175- 181 F7.5 [Msun] e_logMBH-Hb [0.12/0.9]? Uncertainty in logMBH-Hb (LOG_MBH_HB_ERR) 183- 189 F7.5 [Msun] logMBH-Ha [5.2/9.2]? Log, black hole mass from H{alpha} (LOG_MBH_HA) 191- 198 F8.5 [Msun] e_logMBH-Ha [0.13/85]? Uncertainty in logMBH-Ha (LOG_MBH_HA_ERR) -------------------------------------------------------------------------------- Note (1): See Note (7) in DESI Col., 2025, V/161: Although the primary focus of DESI DR1 is on the new main-survey data, DR1 also includes all the survey validation (SV) data which were taken before the start of the main survey: 1. SV1 (Target Selection Validation) tiles were used to verify and refine the target-selection algorithms for the main survey, and include dedicated secondary-target tiles which were used for special programs before we developed the special survey. 2. SV2 (Operations Development) tiles were used to test survey-like DESI operations; and 3. SV3 (One Percent Survey) tiles comprised a high-completeness sample of observations using the final set of DESI target selection algorithms. -------------------------------------------------------------------------------- Byte-by-byte Description of file: spsdss.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 19 A19 --- SDSS SDSS position-based target identifier (SDSS_NAME) 21- 29 F9.5 deg RAdeg Right Ascension, SDSS (J2000) (RA) 31- 39 F9.5 deg DEdeg Declination, SDSS (J2000) (Dec) 41- 47 F7.5 --- zspec [0.059/0.91] Spectroscopic redshift from SDSS (Redshift) 49- 53 I5 --- Plate [266/11561] Plate ID (PLATE) 55- 59 I5 d MJD [51578/58514] MJD of SDSS spectrum (MJD) 61- 64 I4 --- Fiber [1/1000] Fiber ID (FIBERID) 66- 68 A3 --- Trans Changing state (Turn-on or Turn-off) (Transition) 70- 77 F8.5 [10-7W] logL5100 [39.7/45.2] Log, Continuum luminosity at 5100A (LOG_L5100) 79- 87 F9.5 [10-7W] e_logL5100 [0.0016/123] Uncertainty in logL5100 (LOG_L5100_ERR) 89- 96 F8.5 [10-7W] logL2500 [39.4/45.7] Log, Extrapolated luminosity at 2500A (LOG_L2500) 98- 106 F9.5 [10-7W] e_logL2500 [0.0016/123] Uncertainty in logL2500 (LOG_L2500_ERR) 108- 115 F8.5 [10-7W] logLMgII [39.8/43.71]? Log, broad MgII line luminosity (LOG_LMgII) 117- 123 F7.5 [10-7W] e_logLMgII [0.029/3]? Uncertainty in logLMgII (LOG_LMgII_ERR) 125- 132 F8.5 [10-7W] logLHb [35.7/43.3] Log, broad H{beta} line luminosity (LOG_LHB) 134- 142 F9.6 [10-7W] e_logLHb [0/2.8] Uncertainty in logLHb (LOG_LHB_ERR) 144- 151 F8.5 [10-7W] logLHa [37/43.5]? Log, broad H{alpha} line luminosity (LOG_LHA) 153- 161 F9.6 [10-7W] e_logLHa [0/0.91]? Uncertainty in logLHa (LOG_LHA_ERR) 163- 169 F7.5 [Msun] logMBH-Hb [6.5/9.5]? Log, black hole mass from H{beta} (LOG_MBH_HB) 171- 177 F7.5 [Msun] e_logMBH-Hb [0.12/0.9]? Uncertainty in logMBH-Hb (LOG_MBH_HB_ERR) 179- 185 F7.5 [Msun] logMBH-Ha [5/9.1]? Log, black hole mass from H{alpha} (LOG_MBH_HA) 187- 194 F8.5 [Msun] e_logMBH-Ha [0.13/71.4]? Uncertainty in logMBH-Ha (LOG_MBH_HA_ERR) -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Prepared by [AAS], Emmanuelle Perret [CDS] 13-Feb-2026