J/ApJ/749/21 AGNs detected by 60 month Swift/BAT survey (Ajello+, 2012)
The 60 month all-sky Burst Alert Telescope survey of active galactic nucleus
and the anisotropy of nearby AGNs.
Ajello M., Alexander D.M., Greiner J., Madejski G.M., Gehrels N., Burlon D.
<Astrophys. J., 749, 21 (2012)>
=2012ApJ...749...21A 2012ApJ...749...21A
ADC_Keywords: Active gal. nuclei ; X-ray sources ; Surveys ; Redshifts
Mission_Name: Swift
Keywords: cosmology: observations - diffuse radiation - galaxies: active -
surveys - X-rays: diffuse background
Abstract:
Surveys above 10 keV represent one of the best resources to provide an
unbiased census of the population of active galactic nuclei (AGNs). We
present the results of 60 months of observation of the hard X-ray sky
with Swift/Burst Alert Telescope (BAT). In this time frame,
BAT-detected (in the 15-55keV band) 720 sources in an all-sky survey
of which 428 are associated with AGNs, most of which are nearby. Our
sample has negligible incompleteness and statistics a factor of ∼2
larger over similarly complete sets of AGNs. Our sample contains (at
least) 15 bona fide Compton-thick AGNs and 3 likely candidates.
Compton-thick AGNs represent ∼5% of AGN samples detected above 15keV.
We use the BAT data set to refine the determination of the log N-log S
of AGNs which is extremely important, now that NuSTAR prepares for
launch, toward assessing the AGN contribution to the cosmic X-ray
background. We show that the log N-log S of AGNs selected above 10 keV
is now established to ∼10% precision. We derive the luminosity
function of Compton-thick AGNs and measure a space density of
7.9+4.1-2.9x10-5/Mpc3 for objects with a de-absorbed luminosity
larger than 2x1042erg/s. As the BAT AGNs are all mostly local, they
allow us to investigate the spatial distribution of AGNs in the nearby
universe regardless of absorption. We find concentrations of AGNs that
coincide spatially with the largest congregations of matter in the
local (≤85Mpc) universe. There is some evidence that the fraction of
Seyfert 2 objects is larger than average in the direction of these
dense regions.
Description:
For the analysis presented here, we use 60 months of Swift/BAT
observations taken between 2005 March and 2010 March. Data screening
and processing was performed according to the recipes presented in
Ajello et al. (2008, Cat. J/ApJ/678/102) and Ajello et al. (2008,
Cat. J/ApJ/673/96). The chosen energy interval is 15-55 keV. The
all-sky image is obtained as the weighted average of all the shorter
observations.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 105 428 The 428 AGNs detected by BAT
table2.dat 67 18 Known Compton-thick AGNs detected in the BAT sample
--------------------------------------------------------------------------------
See also:
J/ApJS/207/19 : Hard X-ray survey from Swift-BAT 2004-2010 (Baumgartner+, 2013)
J/ApJ/728/58 : Swift-BAT survey of AGNs (Burlon+, 2011)
J/ApJ/739/57 : Ultra hard X-ray AGNs in the Swift/BAT survey (Koss+, 2011)
J/A+A/510/A48 : Palermo Swift-BAT Hard X-ray Catalogue (Cusumano+, 2010)
J/A+A/524/A64 : The 54-month Palermo BAT-survey catalogue (Cusumano+, 2010)
J/ApJS/186/378 : Hard X-ray survey from Swift-BAT 2004-2006 (Tueller+, 2010)
J/ApJ/699/603 : Evolution of Swift/BAT blazars (Ajello+, 2009)
J/ApJ/681/113 : Swift BAT survey of AGNs (Tueller+, 2008)
J/ApJ/673/96 : BAT X-ray Survey. III. (Ajello+, 2008)
J/ApJ/678/102 : BAT X-ray survey. I. (Ajello+, 2008)
J/ApJ/633/L77 : SWIFT/BAT detections of AGN (Markwardt+, 2005)
J/ApJS/121/473 : A diagnostic diagram for Seyfert 2 Galaxies (Bassani+, 1999)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- SWIFT Swift name (JHHMM.m+DDMM)
14- 20 F7.3 deg RAdeg Right Ascension in decimal degrees (J2000)
22- 28 F7.3 deg DEdeg Declination in decimal degrees (J2000)
30- 34 F5.3 arcmin ePos [0.4/7] Position error
36- 40 F5.2 10-14W/m2 Flux [0.6/57] Swift/BAT observed flux in the
15-55keV band (in 10-11erg/s/cm2)
42- 46 F5.1 --- S/N [5/278] Signal to Noise ratio
48- 74 A27 --- ID Source identification
75 A1 --- u_ID [?] Uncertain ID
77- 82 A6 --- Type Source type (AGN, BLAZAR, GiP, LINER, QSO, Sy
or RG) (1)
84- 89 F6.4 --- z [0.001/3.4]? Redshift
91- 94 F4.2 --- Gamma [1.2/3.7] Photon index Γ
96-100 F5.2 --- e_Gamma [0.01/14] Uncertainty in Gamma
102-105 F4.1 [10-7W] logLX [40/49]? Log of X-ray luminosity; in erg/s
--------------------------------------------------------------------------------
Note (1): AGN are sources lacking an exact optical classification.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 A18 --- ID AGN name
20- 22 A3 --- f_ID [,a-d] Flag(s) on ID (1)
24- 28 A5 --- OType AGN type (Sy1, Sy1.8 or Sy2)
30- 37 F8.6 --- z [0.001/0.03] Redshift
39- 46 F8.4 deg RAdeg Right ascension in decimal degrees (J2000)
48- 55 F8.4 deg DEdeg Declination in decimal degrees (J2000)
57 A1 --- l_NH Limit flag on NH
59- 63 F5.2 10+24cm-2 NH [1/10] Hydrogen column density (2)
65- 67 A3 --- r_NH [,ef] Flag(s) on NH (1)
--------------------------------------------------------------------------------
Note (1): Flag as follows:
a = Part of the sample of candidate Compton-thick objects in Della Ceca et
al. (2008MmSAI..79...65D 2008MmSAI..79...65D).
b = NGC 1365 is a complex source that shows a column density that can vary
from log NH∼23 to ≥24 on timescales of ∼10hr (Risaliti et al.
2009MNRAS.393L...1R 2009MNRAS.393L...1R). According to Risaliti et al. (2009ApJ...705L...1R 2009ApJ...705L...1R),
the source has an absorber with log NH∼24.6 which covers ∼80% of the
source.
c = UGC 4203 (also called the "Phoenix" galaxy) is known to exhibit changes in
the absorbing column density from the Compton-thin to the Compton-thick
regime (see, e.g., Risaliti et al. 2010MNRAS.406L..20R 2010MNRAS.406L..20R).
d = Reported to be Compton-thick by Reynolds et al. (1994MNRAS.268L..55R 1994MNRAS.268L..55R), and
Bassani et al. (1999, Cat. J/ApJS/121/473).
e = For the value of the absorbing column density, see Della Ceca et al.
(2008MmSAI..79...65D 2008MmSAI..79...65D) and references therein.
f = Piconcelli et al. (2011A&A...534A.126P 2011A&A...534A.126P) report that this source might be
absorbed by log NH≥25.
Note (2): Unless flagged, the values of the absorbing column density come
from Burlon et al. (2011, Cat. J/ApJ/728/58).
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 08-Nov-2013