J/ApJS/282/13 AGN flares from ZTF DR23 (He+, 2026)
A systematic search for active galactic nucleus flares in ZTF Data Release 23.
He L., Liu Z.-Y., Niu R., Zhou M.-S., Zou P.-R., Gao B.-Z., Liang R.-D.,
Zhu L.-G., Wang J.-M., Jiang N., Cai Z.-Y., Jiang J.-A., Dai Z.-G.,
Yuan Y.-F., Chen Y.-J., Zhao W.
<Astrophys. J. Suppl. Ser., 282, 13 (2026)>
=2026ApJS..282...13H 2026ApJS..282...13H
ADC_Keywords: Active gal. nuclei; QSOs; Photometry; Optical; Redshifts;
Supernovae
Keywords: Active galactic nuclei ; Quasars
Abstract:
Active galactic nuclei (AGNs) are known to exhibit stochastic
variability across a wide range of timescales and wavelengths. AGN
flares are extreme outbursts that deviate from this typical behavior
and may trace a range of energetic physical processes. Using 6yr of
data from Zwicky Transient Facility Data Release 23, we conduct a
systematic search for AGN flares among a sample of well-sampled AGNs
and AGN candidates. We construct two catalogs: the AGN Flare Coarse
Catalog, containing 28,504 flares identified via Bayesian blocks and
Gaussian processes, and the AGN Flare Refined Catalog, comprising 1984
high-confidence flares selected using stricter criteria. We analyze
their spatial distribution, temporal characteristics, host-AGN type,
and potential origins. Some flares can be associated with known
supernovae, tidal disruption events, or blazars, and a few may be
linked to binary black hole mergers or microlensing events.
Description:
The Zwicky Transient Facility (ZTF) is a wide-field time-domain survey
utilizing a 47deg2 field-of-view camera mounted on the Palomar 48inch
Samuel Oschin Schmidt telescope. ZTF has been operating since
2018-March, covering approximately 3π sr across the northern sky.
Our analysis is based on ZTF DR23, publicly released on 2025-Jan-21.
This release consolidates all observations from public surveys up to
2024 October 31 and private surveys prior to 2023 June 30.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 251 28504 AGN flares identified using Gaussian Processes,
showing features distinct from AGN variability
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See also:
VII/274 : The Roma BZCAT - 5th edition (Massaro+, 2015)
II/363 : The band-merged unWISE Catalog (Schlafly+, 2019)
I/356 : Gaia DR3 Part 2. Extra-galactic (Gaia Collaboration, 2022)
I/358 : Gaia DR3 Part 4. Variability (Gaia Collaboration, 2022)
VII/294 : The Million Quasars (Milliquas) catalogue, version 8 (Flesch, 2023)
V/161 : DESI DR1 redshift catalog (DESI Col.+ 2025)
J/ApJ/696/870 : Catalina Real-time Transient Survey (CRTS) (Drake+, 2009)
J/ApJ/698/895 : Variations in QSOs optical flux (Kelly+, 2009)
J/AJ/151/24 : LAMOST quasar survey: QSO properties from the DR1 (Ai+, 2016)
J/MNRAS/463/296 : PS1 slow-blue nuclear hypervariables (Lawrence+, 2016)
J/ApJS/234/23 : The WISE AGN candidates catalogs (Assef+, 2018)
J/AJ/155/189 : LAMOST Quasar Survey: QSO properties from DR2&3 (Dong+, 2018)
J/ApJS/240/6 : LAMOST Quasar Survey: Data Releases 4 and 5 (Yao+, 2019)
J/A+A/674/A41 : Composite quasar spectra from Gaia DR3 (Gaia Coll., 2023)
J/ApJS/265/25 : LAMOST Quasar Survey DR6-DR9 (Jin+, 2023)
J/ApJ/951/134 : X-ray/UV & optical evolution of ASASSN -14ko (Payne+, 2023)
J/ApJ/964/69 : Quaia, the Gaia-unWISE Quasar catalog (Storey-Fisher+, 2024)
http://www.ztf.caltech.edu/ : The Zwicky Transient Facility homepage
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1 I1 --- AGNFRC [0/1] 1=high-confidence flare (1)
3- 21 A19 --- Name AGN name (JHHMMSS.ss+DDMMSS.s)
23- 42 F20.16 deg RAdeg Right Ascension (J2000)
44- 63 F20.16 deg DEdeg [-30/88] Declination (J2000)
65- 69 F5.3 --- z [0/4.7]? Redshift from source catalog
71- 79 A9 --- r_z Source catalog (2)
81- 86 A6 --- Type Source type (3)
88-101 A14 --- Class Classification result from the ALeRCE,
Section 4.3 (4)
103-107 F5.3 --- Pdiff [0/1]? Difference, highest and second-highest
ALeRCE class probabilities
109-113 F5.3 arcsec Offset [0.001/3]? Angular separation, ZTF alert
position (from ALeRCE) and AGN coordinates
115-121 F7.1 d t0 [58188/60623.5] Peak time of the flare, MJD
(JD-2400000.5)
123-128 F6.1 d te [0/4000] Exponential decay timescale of the
flare
130-135 F6.1 d tg [0/4000] Gaussian rise timescale of the flare
137-144 F8.2 uJy r0-g [5.5/11822] Baseline flux density in g band
146-153 F8.2 uJy r0-r [6.9/25150] Baseline flux density in r band
155-162 F8.2 uJy Amp-g [0/40649] Flare amplitude in g band
164-171 F8.2 uJy Amp-r [0/20086] Flare amplitude in r band
173-178 F6.1 d Maxgap [54.2/1793.1] Maximum observational gap in
light curve
180-184 F5.2 --- Sig-gPk [0.7/18] Significance level, peak g band flux
186-190 F5.2 --- Sig-rPk [0.8/18.71] Significance level, peak r band
flux
192-195 F4.1 --- Ng [0/57] Number, non-flare points exceeding
3σ, g band
197-200 F4.1 --- Nr [0/46] Number, non-flare points exceeding
3σ, r band
202-207 F6.1 --- DelBIC [-47.6/1944.4] Difference, BIC for constant
model and flare model
209-213 F5.1 --- Np-g [0/446] Number of points within the flare
interval (t0-tg,t0+te), g band
215-219 F5.1 --- Np-r [0/486] Number of points within the flare
interval (t0-tg,t0+te), r band
221-223 F3.1 --- Fl1 [0/1] Boolean flag, Maxgap>500days
225-227 F3.1 --- Fl2 [0/1] Boolean flag, min(Sig-gPk,Sig-rPk)<3
229-231 F3.1 --- Fl3 [0/1] Boolean flag, Ng+Nr>2
233-235 F3.1 --- Fl4 [0/1] Boolean flag, DelBIC<10
237-239 F3.1 --- Fl5 [0/1] Boolean flag,
t0+te>max(MJD) or t0-tg<min(MJD)
241-243 F3.1 --- Fl6 [0/1] Boolean flag, min(Np-g,Np-r)<(tg+te)/20
245-247 F3.1 --- Fl7 [0/1] Boolean flag,
min(Amp-g/r0-g, Amp-r/r0-r)<0.2
249-251 F3.1 --- Fl8 [0/1] Boolean flag, AGN is confused with
other sources
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Note (1): All entries are members of the AGN Flare Coarse Catalog
(AGNFCC); entries flagged with a value of AGNFRC=1 are a subset
1,984 AGN flares from the AGNFCC, refined through more stringent
criteria (AGN Flare Refined Catalog).
Note (2): Source catalog as follows:
M = Million Quasars Catalog (Milliquas), v8 (Flesch 2023, VII/294)
D = DESI AGN Catalog, DESI. Coll. (2025, V/161)
L = LAMOST AGN Catalog, Ai+ (2016, J/AJ/151/24);
Dong+ (2018, J/AJ/155/189); Yao+ (2019, J/ApJS/240/6);
Jin+ (2023, J/ApJS/265/25)
Q = Quaia AGN Catalog, Storey-Fisher+ 2024, J/ApJ/964/69
W = WISE AGN R90 Catalog, Assef+ 2018, J/ApJS/234/23
Note (3): Source type as follows:
Blazar = 830 occurrences
SN = supernova (59 occurrences)
TDE = tidal disruption event (2 occurrences)
Note (4): Highest probability class from the Automatic Learning for the Rapid
Classification of Events (ALeRCE) broker classifier
(Sanchez-Saez+ 2021AJ....161..141S 2021AJ....161..141S). Class as follows:
QSO = 4582 occurrences
AGN = 3278 occurrences
Blazar = 2039 occurrences
CV/Nova = 126 occurrences
SN = 402 occurrences
SLSN = 87 occurrences
SNII = 28 occurrences
SNIa = 46 occurrences
SNIbc = 22 occurrences
YSO = 96 occurrences
VS = 55 occurrences
RRL = 7 occurrences
LPV = 4 occurrences
Periodic-Other = 16 occurrences
asteroid = 40 occurrences
bogus = 584 occurrences
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History:
From electronic version of the journal
License: CC-BY-4.0
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 10-Jul-2026