J/A+A/707/A213 5 AGNs soft excess and X-ray continuum (Jana+, 2026)
Multiwavelength properties of changing-state active galactic nuclei.
I. The evolution of soft excess and X-ray continuum.
Jana A., Ricci C., Tortosa A., Dimopoulos G., Trakhtenbrot B., Bauer F.E.,
Temple M., Koss M., Gupta K.K., Chang H.-K., Diaz Y., Illic Y., Kallova K.,
Shablovinskaya E.
<Astron. Astrophys. 707, A213 (2026)>
=2026A&A...707A.213J 2026A&A...707A.213J (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; X-ray sources ; Accretion
Keywords: accretion, accretion disks - galaxies: active - galaxies: nuclei -
quasars: supermassive black holes - X-rays: galaxies
Abstract:
Changing-state active galactic nuclei (CSAGNs) exhibit rapid
variability, with mass accretion rates that can change by several
orders of magnitude in a few years. This provides us with a unique
opportunity to study the evolution of the inner accretion flow almost
in real time. Here, we used over 1000 observations to study the
broadband X-ray spectra of a sample of five CSAGNs, spanning three
orders of magnitude in Eddington ratio (λEdd), using
phenomenological models to trace the evolution of key spectral
components. We derive several fundamental parameters, such as the
photon index, soft excess strength, reflection strength, and
luminosities of the soft excess and primary continuum. We find that
the soft excess and primary continuum emissions show a very strong
positive correlation (p≪10-10), suggesting a common physical
origin. The soft excess strength does not show any dependency on the
reflection parameter, suggesting that in these objects the soft excess
is not dominated by a blurred ionized reflection process. On the other
hand, the strength of the soft excess is found to be strongly
positively correlated with the Eddington ratio (p≪10-10), and we
find that the soft excess vanishes below log λEdd~-2.5.
Moreover, we find a clear 'V'-shaped relation for
Γ-λEdd, with a break at logλEdd=-2.47±0.09. Our
findings indicate a change in the geometry of the inner accretion flow
at low Eddington ratios, and that the soft excess is primarily
produced via warm Comptonization.
Description:
The table contains the information of optical and X-ray observations
of our sample of changing look AGNs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 61 5 General properties of the sample of CSAGNs
tableb.dat 111 214 Data analysis result (tables B1-B5)
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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- 15 A15 --- Name Common name
17- 20 I4 --- BAT BAT ID
22- 28 F7.3 deg RAdeg Right ascension (J2000)
30- 36 F7.3 deg DEdeg Declination (J2000)
38- 43 F6.4 --- z Redshift
45- 49 F5.1 Mpc dL Luminosity distance
51- 54 F4.2 Msun MBH Black hole mass
56- 59 F4.2 Msun e_MBH ? Black hole mass error
61 A1 --- r_MBH Black hole mass reference (1)
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Note (1): References for mass as follows:
A = Koss et al. (2022ApJS..261....6K 2022ApJS..261....6K, Cat. J/ApJS/261/6)
B = Feng et al. (2021ApJ...912...92F 2021ApJ...912...92F, Cat. J/ApJ/912/92)
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Byte-by-byte Description of file: tableb.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Name (1)
18- 20 I3 --- ID [1/214] Sequential number
22- 29 F8.2 d ObsStart Observation start date (MJD)
31- 38 F8.2 d ObsEnd Observation end dat (MJD)
40 I1 --- Type Spectral type
42- 44 I3 eV kTBB Temperature of BB
46- 47 I2 eV e_kTBB ? Error of kTBB
49- 52 F4.2 --- Gamma Photon index
54- 57 F4.2 --- e_Gamma Error of Gamma
59 A1 --- l_logLSE Limit flag on Gamma
60- 64 F5.2 [10-7W] logLSE 0.5-2 keV SE luminosity
66- 69 F4.2 [10-7W] e_logLSE ? Error of SE luminosity
71- 75 F5.2 [10-7W] logLPC 2-10 keV PC luminosity
77- 80 F4.2 [10-7W] e_logLPC Error of L_PC
82- 86 F5.2 --- logEddR ? Eddington Ratio
88- 91 F4.2 --- e_logEddR ? Error of Eddington ratio
93 A1 --- l_logQ Limit flag on logQ
94- 98 F5.2 --- logQ Soft excess strength
100-103 F4.2 --- e_logQ ? Error of SE strength
105-107 I3 --- C Cash-statistics
109-111 I3 --- dof Degrees-of-freedom
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Note (1): NGC1566 (ID 1-37), NGC2617 (ID 38-115), MRK1018 (ID 175-194),
IRAS23226-3843 (ID 195-214).
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Acknowledgements:
Arghajit Jana, argha0004(at)gmail.com
(End) Patricia Vannier [CDS] 16-Jan-2026