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.
<Astrophys. J. Suppl. Ser., 278, 28 (2025)>
=2025ApJS..278...28G 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 Hβ, 149 Hα, 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
λEdd∼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 Hβ 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 ΛCDM cosmology with
H0=67km/s/Mpc, ΩΛ=0.68, and Ωm=0.32.
File Summary:
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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
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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
5100Å (LOG_L5100)
85- 93 F9.5 [10-7W] e_logL5100 [0.0028/146.5] Uncertainty in logL5100
(LOGL5100ERR)
95- 102 F8.5 [10-7W] logL2500 [40/45.5] Log, Extrapolated luminosity at
2500Å (LOG_L2500)
104- 112 F9.5 [10-7W] e_logL2500 [0.0028/146.5] Uncertainty in logL2500
(LOGL2500ERR)
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
(LOGLMgIIERR)
131- 138 F8.5 [10-7W] logLHb [36.3/43.4] Log, broad Hβ line
luminosity (LOG_LHB)
140- 147 F8.6 [10-7W] e_logLHb [0/3] Uncertainty in logLHb (LOGLHBERR)
149- 156 F8.5 [10-7W] logLHa [39.29/43.3]? Log, broad Hα line
luminosity (LOG_LHA)
158- 165 F8.6 [10-7W] e_logLHa [0/2.6]? Uncertainty in logLHa
(LOGLHAERR)
167- 173 F7.5 [Msun] logMBH-Hb [6.49/9.51]? Log, black hole mass from
Hβ (LOGMBHHB)
175- 181 F7.5 [Msun] e_logMBH-Hb [0.12/0.9]? Uncertainty in logMBH-Hb
(LOGMBHHB_ERR)
183- 189 F7.5 [Msun] logMBH-Ha [5.2/9.2]? Log, black hole mass from
Hα (LOGMBHHA)
191- 198 F8.5 [Msun] e_logMBH-Ha [0.13/85]? Uncertainty in logMBH-Ha
(LOGMBHHA_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.
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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
(LOGL5100ERR)
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
(LOGL2500ERR)
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
(LOGLMgIIERR)
125- 132 F8.5 [10-7W] logLHb [35.7/43.3] Log, broad Hβ line
luminosity (LOG_LHB)
134- 142 F9.6 [10-7W] e_logLHb [0/2.8] Uncertainty in logLHb
(LOGLHBERR)
144- 151 F8.5 [10-7W] logLHa [37/43.5]? Log, broad Hα line
luminosity (LOG_LHA)
153- 161 F9.6 [10-7W] e_logLHa [0/0.91]? Uncertainty in logLHa
(LOGLHAERR)
163- 169 F7.5 [Msun] logMBH-Hb [6.5/9.5]? Log, black hole mass from
Hβ (LOGMBHHB)
171- 177 F7.5 [Msun] e_logMBH-Hb [0.12/0.9]? Uncertainty in logMBH-Hb
(LOGMBHHB_ERR)
179- 185 F7.5 [Msun] logMBH-Ha [5/9.1]? Log, black hole mass from
Hα (LOGMBHHA)
187- 194 F8.5 [Msun] e_logMBH-Ha [0.13/71.4]? Uncertainty in logMBH-Ha
(LOGMBHHA_ERR)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 13-Feb-2026