J/A+A/693/A35 Changing-look active galactic nuclei (Jana+, 2025)
Investigating changing-look active galactic nuclei with long-term optical
and X-ray observations.
Jana A., Ricci C., Temple M.J., Chang H.-K., Shablovinskaya E.,
Trakhtenbrot B., Diaz Y., Ilic D., Nandi P., Koss M.
<Astron. Astrophys. 693, A35 (2025)>
=2025A&A...693A..35J 2025A&A...693A..35J (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Spectroscopy ; Optical ; Ultraviolet ;
X-ray sources
Keywords: accretion, accretion disks - galaxies: active - galaxies: nuclei -
quasars: supermassive black holes - X-rays: galaxies
Abstract:
Changing-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.
Description:
We conducted a comprehensive study of 20 optically identified
changing-look active galactic nuclei in the local Universe (z < 0.06)
using quasi-simultaneous optical and X-ray observations from BASS.
The table contains the information of optical and X-ray observations.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 196 20 List of CLAGNs
tablec.dat 98 528 Information of optical and X-ray observations
for the 20 clusters (tables C1-C20)
refs.dat 71 235 References
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- No Sequential number
4- 18 A15 --- Name Cluster name
20- 23 I4 --- BAT BAT ID
25- 32 F8.4 deg RAdeg right ascension (J2000)
34- 40 F7.3 deg DEdeg Decliination (J2000)
42- 47 F6.4 --- z Redshift
49- 52 F4.2 [Msun] logMBH Mass of the black hole
54- 57 F4.2 [Msun] e_logMBH ? Mass of the black hole error
59 I1 --- r_logMBH [1/3] References for black hole mass (1)
61-196 A136 --- CLTrans Information of the optical spectral states
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Note (1): References for MBH as follows:
1 = Koss et al. (2017ApJ...850...74K 2017ApJ...850...74K, Cat. J/ApJ/850/74)
2 = Koss et al. (2022ApJS..261....2K 2022ApJS..261....2K, Cat. J/ApJ/261/2)
3 = Feng et al. (2021ApJ...916...61F 2021ApJ...916...61F)
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Byte-by-byte Description of file: tablec.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Cluster name
17- 26 A10 "date" Obs.date UT observation date
28 A1 --- BroadHb [YN-] Broad Hbeta Y = present, N = absent
30 A1 --- BroadHa [YN-] Broad Halpha Y = present, N = absent
32- 34 F3.1 --- Type ?=- Optical spectral state
36- 42 A7 --- TelO Optical Telescope (1)
44- 48 F5.2 [10-7W] logLbol ?=- Bolometric luminosity (erg/s)
50- 53 F4.2 [10-7W] e_logLbol ?=- Error of Lbol (erg/s)
55- 59 F5.2 --- Eddratio ?=- Eddington ratio
61- 64 F4.2 --- e_Eddratio ?=- Error of Eddington ratio
66- 70 F5.2 [cm-2] logNH ?=- Hydrogen column density
72- 75 F4.2 [cm-2] e_logNH ?=- Error of N_H
77- 85 A9 --- TelX X-ray telescope (2)
87- 93 A7 --- Refs References, in refs.dat file
95 A1 --- l_tCL Limit flag on tCL
96- 98 I3 d tCL ?=- CL Transition time
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Note (1): Optical telescopes as follows:
AAT1 = AAT/IDS
AAT2 = AAT/IPCS
AAT3 = AAT 3.9m/RGOS
ANU1 = ANU 2.3m/DBS
ANU1 = ANU 2.3m/WiFeS
APO = APO 3.5m/DIS
BAO = BAO 2.16m/OMS
CA2 = CAO 2.2m/B&C
CA3 = CAO 3.5m/TWIN
CA1 = CA 3.5m
CA5 = CAO 2.2m/CAFOS
CAO = CAO 3.5m/CCDS
CMO = CMO 2.5m
CMO1 = CMO/SAI 2.5m
CNPq = CNPq 1.6m
CTIO1 = CTIO 1.5m/RCS
CTIO2 = CTIO 2.1m/RCS
CTIO4 = CTIO 4m/R-C
CrAO = CrAO 2.6m
Danish = Danish 1.54m/DFOSC
ESO1e = ESO/EC
ESO1i = ESO3.6m/IDS
ESO2b = ESO 2.2m/BCS
ESO2i = ESO1.5m/IDS
ESO3 = ESO 1.52m/BCS
ESO4 = ESO/NTT
ESOb = ESO 1.52m/BCS
ESOc = ESO 1.5m
ESOd = ESO 3.6m/CAS
ESOe = ESO 3.6m/EFOSC2
FAST = FLWO 1.5m/FAST
GHO = GHO 2.1m/B&C
Gemini = Gemini 8.1m/GMOS-IFU
HST = HST/FOS
HST2 = HST/STIS
Hale1 = Hale 200inch/DBPS
Hale2 = Hale/5.08m
KPNO = KPNO 2.1m/Goldcam
Keck = Keck 10m/LRIS
LBT = LBT 8.4m/MODS
LCO = LCO/FLOYD
Lick-N = Lick-Nickel 40inch
Lick = Lick 3m/Shane
Lick2 = Lick-Shane 3m/Kast
Lijang = Lijang 2.4m/YFOSC
Lowell1 = Lowell-Perkins/Deveny
Lowell2 = Lowell/IDS
MDM-B = MDM 1.3m/BCS
MDM1 = MDM 1.3m/CCDS
MDM2 = MDM 2.4m/OSMOS
MDM3 = MDM 1.3m
MDM4 = MDM 2.4m
MMT = MMT/BCS
MSO = MSO/IT
Mag = Magellan/MagE
Mayall = Mayall 4m/KOSMOS
Mt. HT = Mt. Hopkins 1.6m
NTT = ESO-NTT/EMMI
Oky = Okayama 188cm
Palomar = Palomar 1.5m/SIT
Perkins = Lowell-Perkins 1.8m/IDS
RCT = RCT/REOSC
SALT1 = SALT 10m
SALT2 = SALT/RSS
SAO6 = SA0 6m/UAGS
SAO1 = SAO 1m/UAGS
SAOO1 = SAOO 1.9m
SAOOm = SAOO/MASTER-IIs
SOAR = SOAR/SIFS
Subaru = Subaru 8.2m/HDS
UCSD = UCSD/UMinn 1.5m
UH88 = UH 88inch/SNIFS
UKS = UK Schmidt 1.2m
VLT-F = VLT/FORS2
VLT-M = VLT/MUSE
VLT-X = VLT/Xshooter
WIRO = WIRO 2.3m
WO = Wise 1m
duPONT = duPONT/B&C
Note (2): X-ray telescopes as follows:
A-V = Arial V /SSI
ASCA = ASCA/GIS+SIS
BS = BeppoSAX /PDS
Ch = Chandra/ACIS
Ch = Chandra/ACIS-LETG
EXO1 = EXOSAT/LE+ME
EXO2 = EXOSAT/ME
EinI = Einstein/IPC
EinM = Einstein/MPC
G = Ginga/LAC
Ginga = Ginga/LAC
H-1 = HEAO-1
H1 = HEAO-1
Nu = NuSTAR/FPMA+FPMB
ROSAT1 = ROSAT/HRI
ROSAT2 = ROSAT/PSPC
RXTE = RXTE/ PCA
Suz = Suzaku/XIS
Swift = Swift/XRT
XMM = XMM-Newton/EPIC-PN
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Ref Reference code
5- 31 A27 --- Aut Author's name
33- 51 A19 --- BibCode BibCode
53- 71 A19 --- Com Comments
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Acknowledgements:
Arghajit Jana, argha0004(at)gmail.com
(End) Patricia Vannier [CDS] 15-Nov-2024