J/ApJ/815/L13 Compton-thick AGNs from the 70-month Swift/BAT cat. (Ricci+, 2015)
Compton-thick accretion in the local universe.
Ricci C., Ueda Y., Koss M.J., Trakhtenbrot B., Bauer F.E., Gandhi P.
<Astrophys. J., 815, L13 (2015)>
=2015ApJ...815L..13R 2015ApJ...815L..13R (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; X-ray sources ; Redshifts ;
Equivalent widths ; Cross identifications
Keywords: galaxies: active; galaxies: Seyfert; quasars: general;
X-rays: diffuse background; X-rays: general
Abstract:
Heavily obscured accretion is believed to represent an important stage
in the growth of supermassive black holes and to play an important
role in shaping the observed spectrum of the cosmic X-ray background.
Hard X-ray (E>10keV) selected samples are less affected by absorption
than samples selected at lower energies, and are therefore one of the
best ways to detect and identify Compton-thick (CT, logNH≥24)
active galactic nuclei (AGNs). In this letter we present the first
results of the largest broadband (0.3-150keV) X-ray spectral study of
hard X-ray selected AGNs to date, focusing on the properties of
heavily obscured sources. Our sample includes the 834 AGNs (728
non-blazar, average redshift z∼0.055) reported in the 70-month catalog
of the all-sky hard X-ray Swift/Burst Alert Monitor survey. We find 55
CT AGNs, which represent 7.6-2.1+1.1% of our non-blazar sample. Of
these, 26 are reported as candidate CT AGNs for the first time. We
correct for selection bias and derive the intrinsic column density
distribution of AGNs in the local universe in two different luminosity
ranges. We find a significant decrease in the fraction of obscured
Compton-thin AGNs for increasing luminosity, from 46±3% (for
logL14-195=40-43.7) to 39±3% (for logL14-195=43.7-46). A similar
trend is also found for CT AGNs. The intrinsic fraction of CT AGNs
with logNH=24-25 normalized to unity in the logNH=20-25 range is
27±4%, and is consistent with the observed value obtained for AGNs
located within 20Mpc.
Description:
Our group has recently carried out the largest study of broadband
X-ray emission of AGNs (C. Ricci et al. 2015, in preparation),
analyzing in detail the 0.3-150keV spectra of the 834 AGNs reported in
the latest release (70 months, Baumgartner et al. 2013, J/ApJS/207/19)
of the Swift/BAT catalog. We present here the first results of our
work, focused on the detection of 55 Compton-thick (CT) AGNs, 26 of
which are reported for the first time as candidate CT sources.
We collected the best X-ray data below 10keV available as of 2013
March, using spectra from XMM-Newton, Chandra, Suzaku, Swift/XRT, and
ASCA (Advanced Satellite for Cosmology and Astrophysics).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 151 55 Compton-thick (CT, logNH≥24) AGNs in the
Swift/BAT 70-month catalog
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-2014)
B/xmm : XMM-Newton Obs. Log (XMM-Newton Science Operation Center, 2012)
VII/274 : The Roma BZCAT - 5th edition (Massaro+, 2015)
J/ApJ/808/185 : NuSTAR surveys: COSMOS catalog (Civano+, 2015)
J/ApJ/802/89 : Luminosity function of X-ray-selected AGNs (Buchner+, 2015)
J/ApJS/207/19 : Hard X-ray survey from Swift-BAT 2004-2010 (Baumgartner+, 2013)
J/ApJ/763/111 : X-ray spectral analysis of Swift/BAT AGNs (Vasudevan+, 2013)
J/ApJ/749/21 : AGNs detected by 60 month Swift/BAT survey (Ajello+, 2012)
J/MNRAS/413/1206 : XMM survey of 12um selected galaxies (Brightman+, 2011)
J/ApJ/739/57 : Ultra hard X-ray AGNs in the Swift/BAT survey (Koss+, 2011)
J/ApJ/728/58 : Swift-BAT survey of AGNs (Burlon+, 2011)
J/A+A/524/A64 : The 54-month Palermo BAT-survey catalogue (Cusumano+, 2010)
J/A+A/520/A47 : Blazars in the Swift-BAT hard X-ray sky (Maselli+, 2010)
J/A+A/505/417 : Second INTEGRAL AGN catalogue (Beckmann+, 2009)
J/ApJ/681/113 : Swift BAT survey of AGNs (Tueller+, 2008)
J/ApJ/673/96 : BAT X-ray Survey - III (Ajello+, 2008)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- --- [SWIFT]
7- 19 A13 --- SWIFT Swift identifier (JHHMM.m+DDMMA)
21- 25 A5 --- f_SWIFT Flag on SWIFT (1)
27- 50 A24 --- XID Counterpart name
52- 54 F3.1 --- Type ? Optical classification (2)
55 A1 --- r_Type [c] Flag on Type (1)
57- 62 F6.4 --- z [0.001/0.3] Redshift
64- 68 F5.2 cm-2 logNH [24/25.6] Hydrogen column density
70- 74 F5.2 cm-2 b_logNH [23.7/25.1] 90% confidence lower value of logNH
76- 80 F5.2 cm-2 B_logNH [24/25.5]? 90% confidence upper value of logNH
82 A1 --- fBlogNH [n] n: B_logNH is not constrained
84- 85 A2 --- l_EW [≤> ] Limit flag on EW
87- 90 I4 eV EW [0/7300]? Fe Kα equivalent width
92- 95 I4 eV E_EW [32/4056]? Positive error on EW
97-100 I4 eV e_EW [6/5641]? Negative error on EW
102 A1 --- f_EW [n] n: EW is not constrained
104-108 F5.2 --- Gam2-10 [-3/1.3]? 2-10keV photon index (3)
110-113 F4.2 --- E_Gam2-10 [0.02/5.1]? Positive error on Gam2-10
115-118 F4.2 --- e_Gam2-10 [0/2.6]? Negative error on Gam2-10
120 A1 --- f_Gam2-10 [n] n: Blank value(s) are not constrained
122-125 F4.2 --- Gamma [1.4/2.8] 0.3-150keV photon index
127-130 F4.2 --- E_Gamma [0.01/0.9] Positive error on Gamma
132-135 F4.2 --- e_Gamma [0.01/1] Negative error on Gamma
137-141 F5.2 [10-7W] logL2-10 [41.3/45.3] 2-10keV intrinsic luminosity
(i.e., absorption and k-corrected) in erg/s
143-147 F5.2 [10-7W] logL [42/45.3] 14-150keV intrinsic luminosity
(i.e., absorption and k-corrected) in erg/s
149-151 A3 --- Obs X-ray observatory used for the soft
X-ray spectra (4)
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Note (1): Flag as follows:
* = Newly identified Compton-thin AGNs.
a = Sources reported to be Compton-thin by previous works due to the narrower
energy band used for the X-ray spectral analysis.
b = Fe Kα line not detected because of the low signal-to-noise ratio of
the Swift/XRT observation.
c = Optical classification from the literature.
d = Sources reported to be CT by M. Koss et al. (2015, in preparation)
thanks to NuSTAR observations.
e = Swift/BAT flux due to the combined emission of NGC 6921 & MCG+04-48-002.
The 14-150keV luminosity reported refers only to NGC 6921.
Note (2): The optical classifications are taken from the Swift/BAT Spectral
Survey (BASS paper I; M. Koss et al. 2016, in preparation) unless
stated otherwise. BASS will report the optical characteristics of more
than 500 BAT-selected AGNs.
Note (3): Photon index obtained by fitting the spectrum in the 2-10keV range
with a power law.
Note (4): X-ray observatory as follows:
CA = Chandra/ACIS;
SuX = Suzaku/XIS;
SX = Swift/XRT;
XE = XMM-Newton/EPIC
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 09-Mar-2016