J/MNRAS/454/1202 INTEGRAL sample of non-blazar AGN at |b|>5deg (Sazonov+, 2015)
Does the obscured AGN fraction really depend on luminosity?
Sazonov S., Churazov E., Krivonos R.
<Mon. Not. R. Astron. Soc., 454, 1202-1220 (2015)>
=2015MNRAS.454.1202S 2015MNRAS.454.1202S (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Redshifts ; X-ray sources
Keywords: galaxies: active - galaxies: nuclei - galaxies: Seyfert
Abstract:
We use a sample of 151 local non-blazar active galactic nuclei (AGN)
selected from the INTEGRAL all-sky hard X-ray survey to investigate if
the observed declining trend of the fraction of obscured (i.e. showing
X-ray absorption) AGN with increasing luminosity is mostly an
intrinsic or selection effect. Using a torus-obscuration model, we
demonstrate that in addition to negative bias, due to absorption in
the torus, in finding obscured AGN in hard X-ray flux-limited surveys,
there is also positive bias in finding unobscured AGN, due to Compton
reflection in the torus. These biases can be even stronger taking into
account plausible intrinsic collimation of hard X-ray emission along
the axis of the obscuring torus. Given the AGN luminosity function,
which steepens at high luminosities, these observational biases lead
to a decreasing observed fraction of obscured AGN with increasing
luminosity even if this fraction has no intrinsic luminosity
dependence. We find that if the central hard X-ray source in AGN is
isotropic, the intrinsic (i.e. corrected for biases) obscured AGN
fraction still shows a declining trend with luminosity, although the
intrinsic obscured fraction is significantly larger than the observed
one.
Description:
The catalogue contains 151 non-blazar (i.e. Seyfert-like) AGN at
|b|>5 deg. All AGN have known distances and reliable estimates of
their absorption columns based on X-ray spectroscopy.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 75 151 INTEGRAL sample of non-blazar AGN at |b|>5 deg
refs.dat 65 65 References
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See also:
J/A+A/523/A61 : INTEGRAL all-sky survey of hard X-ray sources
(Krivonos+, 2010)
J/MNRAS/510/4796 : INTEGRAL/IBIS 17-yr hard X-ray all-sky survey
(Krivonos+, 2022)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/518] Running number (1)
5- 25 A21 --- Name Object name
27- 33 F7.3 deg RAdeg Right Ascension (J2000)
35- 41 F7.3 deg DEdeg Declination (J2000)
43- 48 F6.1 Mpc Dist Distance
50 A1 --- f_Dist Distance flag (2)
52- 57 F6.4 --- z Redshift
59- 63 F5.2 [10-7W] logL Logarithm of 17-60keV luminosity, erg/s
65 A1 --- l_NH [<≳] Limit flag on NH (3)
66- 69 I4 10+22cm-2 NH Absorption column density
71- 75 A5 --- r_NH NH reference paper
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Note (1): The corresponding running number of the INTEGRAL 7-year survey
(Krivonos et al., 2010A&A...523A..61K 2010A&A...523A..61K, Cat. J/A+A/523/A61).
Note (2): Flag indicates that distance is adopted from the Extragalactic
Distance Database, rather than calculated from the redshift.
Note (3): The type of NH value, specified in column:
< = lower limit, > = upper limit, ∼ = approximate value,
else measured value.
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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- 2 I2 --- Ref Reference number
4- 22 A19 --- BibCode BibCode
24- 43 A20 --- Aut Author's name
45- 65 A21 --- Com Comments
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Acknowledgements:
Roman Krivonos, krivonos(at)cosmos.ru
(End) Patricia Vannier [CDS] 10-Jan-2025