J/PASJ/70/S36 X-ray-bright optically faint AGN (Terashima+, 2018)
X-ray-bright optically faint active galactic nuclei in the
Subaru Hyper Suprime-Cam wide survey.
Terashima Y., Suganuma M., Akiyama M., Greene J.E., Kawaguchi T.,
Iwasawa K., Nagao T., Noda H., Toba Y., Ueda Y., Yamashita T.
<Publ. Astron. Soc. Jap., 70, S36 (2018)>
=2018PASJ...70S..36T 2018PASJ...70S..36T (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; QSOs ; X-ray sources ;
Millimetric/submm sources
Keywords: galaxies: active - galaxies:: supermassive black holes -
X-rays: galaxies
Abstract:
We construct a sample of X-ray-bright optically faint active galactic
nuclei by combining Subaru Hyper Suprime-Cam, XMM-Newton, and infrared
source catalogs. Fifty-three X-ray sources satisfying i-band magnitude
fainter than 23.5mag and X-ray counts with the EPIC-PN detector larger
than 70 are selected from 9.1 deg2, and their spectral energy
distributions (SEDs) and X-ray spectra are analyzed. Forty-four
objects with an X-ray to i-band flux ratio FX/Fi>10 are classified as
extreme X-ray-to-optical flux sources. Spectral energy distributions
of 48 among 53 are represented by templates of type 2 AGNs or
star-forming galaxies and show the optical signature of stellar
emission from host galaxies in the source rest frame. Infrared/optical
SEDs indicate a significant contribution of emission from dust to the
infrared fluxes, and that the central AGN is dust obscured. The
photometric redshifts determined from the SEDs are in the range of
0.6-2.5. The X-ray spectra are fitted by an absorbed power-law
model, and the intrinsic absorption column densities are modest
(best-fit logNH=20.5-23.5cm-2 in most cases). The
absorption-corrected X-ray luminosities are in the range of
6x1042-2x1045erg/s. Twenty objects are classified as type 2
quasars based on X-ray luminosity and NH. The optical faintness is
explained by a combination of redshifts (mostly z>1.0), strong dust
extinction, and in part a large ratio of dust/gas.
Description:
The XMM-Newton Large Scale Structure Survey (LSS: Pierre et al., 2004,
J. Cosmol. Astropart. Phys., 9, 11) and its extension (the Ultimate
XMM-Newton survey, XXL; Pierre et al. 2016A&A...592A...1P 2016A&A...592A...1P, Cat. IX/49)
are X-ray surveys covering large consecutive fields (25 deg2 in the
northern field), which enable us to study large-scale structures and
to find rare X-ray-emitting populations. We use a part of the XXL
northern field covered by HSC and the Spitzer space telescope.
The XMM serendipitous source catalogue data release 6 (3XMM-DR6: Rosen
et al., 2016A&A...590A...1R 2016A&A...590A...1R, See Cat. IX/50) is used as an X-ray
source catalog. The 3XMM-DR6 catalog utilizes XMM-Newton observations
performed by 2015 June 4, and contains some pointed observations in
the XXL region with a longer exposure time than those of the original
survey. Thus we fully utilize X-ray sources detected in such
additional pointings. Since our aims are to select X-ray-bright
optically faint sources and understand their nature, we use objects
with X-ray counts obtained with the EPIC-PN detector in 0.2-12keV
listed in the 3XMM-DR6 catalogue greater than 70 so that X-ray
spectral fits can be performed. This count limit roughly corresponds
to an X-ray flux of ∼10-14erg/s/cm2 in the 2-10keV band, though
conversion to an X-ray flux depends on exposure time and assumed X-ray
spectra. If an X-ray source is observed more than twice, the
observation giving the largest X-ray counts is used.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 56 53 Results of SED fits
table4.dat 70 53 Results of power-law fits to X-ray spectra
table5.dat 55 53 Results of absorbed power law fits to X-ray
spectra
table6.dat 50 53 Flux ratios
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See also:
IX/49 : XXL Survey: First results (Pierre+, 2016)
IX/50 : XMM-Newton Serendipitous Source Catalogue 3XMM-DR6 (XMM-SSC, 2016)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- 3XMM 3XMM name (JHHMMSS.s+DDMMSS)
18- 22 F5.3 --- zph Photometric redshift
24- 27 F4.2 mag AV Extinction in V band
29- 37 A9 --- SED Adopted SED template (1)
39- 42 A4 --- Class1 Classification of SED type (AGN1, AGN2 or SF)
44- 48 F5.3 --- zsp ? Spectroscopic redshift presented in
Akiyama et al. (2015PASJ...67...82A 2015PASJ...67...82A)
50- 52 A3 --- Class2 Spectroscopic classification in
Akiyama et al. (2015PASJ...67...82A 2015PASJ...67...82A) (2)
54- 56 A3 --- Note [a,bc ] Note (3)
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Note (1): "+ IR" denotes the existence of infrared excess compared to model
in fit without Spitzer data.
Note (2): Spectroscopic classification as follows:
NLA = narrow-line AGN
BLA = broad-line AGN
Note (3): Notes as follows:
a = Redshift range in fit was restricted to 1<z<2
b = Spitzer data was excluded in fit
c = Redshift range in fit was restricted to 2<z<3
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- 3XMM 3XMM name (JHHMMSS.s+DDMMSS)
18- 27 I10 --- ObsID Observation ID
29- 31 I3 ct NetCt Net counts in the 0.5-10keV band (counts
from all the available sensors are summed)
33- 36 F4.2 10+20cm-2 NH Galactic absorption column density
38- 41 F4.2 --- GAMMA Photon index
42 A1 --- --- [+]
43- 46 F4.2 --- E_GAMMA Error on Photon index (upper value)
47 A1 --- --- [-]
48- 51 F4.2 --- e_GAMMA Error on Photon index (lower value)
53- 57 F5.2 10-17W/m2 Flux Observed flux in the 2-10keV band
in units of 10-14erg/cm2/s
59- 64 F6.2 --- C C statistic
65 A1 --- --- [/]
66- 68 I3 --- DOF Degrees of freedom
70 A1 --- Note [a-f] Notes (1)
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Note (1): Notes as follows:
a = Different normalization of power law for EPIC-PN and EPIC-MOS are
allowed in fit. Flux is for EPIC-PN
b = Only EPIC-PN is used. At chip boundary in EPIC-MOS1 and EPIC-MOS2
c = Only EPIC-PN and EPIC-MOS1 are used. Out of field of view of EPIC-MOS2
d = Only EPIC-PN and EPIC-MOS1 are used. Located at chip boundary in
EPIC-MOS1
e = Only EPIC-PN is used. Not clearly visible in EPIC-MOS1 image and
located at chip boundary in EPIC-MOS2
f = Only EPIC-PN is used. Out of field of view of EPIC-MOS1 and at edge
of field of view of EPIC-MOS2
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- 3XMM 3XMM name (JHHMMSS.s+DDMMSS) (1)
18- 23 F6.3 10+22cm-2 NH Intrinsic absorption column density at
source redshift (2)
24 A1 --- --- [+]
25- 30 F6.3 10+22cm-2 E_NH Error on NH (upper value)
31 A1 --- --- [-]
32- 36 F5.3 10+22cm-2 e_NH Error on NH (lower value)
38- 44 F7.4 10+37W L2-10 X-ray luminosity in 2-10keV corrected for the
Galactic and intrinsic absorption (3)
47- 51 F5.1 --- C C statistic
52 A1 --- --- [/]
53- 55 I3 --- DOF Degrees of freedom
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Note (1): Observation ID and assumed Galactic absorption column density are
the same as in table 4.
Note (2): Photometric or spectroscopic (when available) redshifts are assumed in
the spectral fits.
Note (3): Photometric or spectroscopic (when available) redshifts are assumed.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- 3XMM 3XMM name (JHHMMSS.s+DDMMSS)
18- 23 F6.3 mag imag Cmodel magnitude in the i band, Galactic
extinction is not corrected
25- 29 F5.1 --- FX/Fi X-ray to i-band flux ratio (1)
31- 34 F4.2 --- FX/F24 ?=- X-ray to 24um flux ratio (2)
36- 39 F4.2 mag i-[3.6] Subaru-IRAC i-[3.6] colour index
41- 44 F4.2 mag [3.6]-[4.5] IRAC [3.6]-[4.5] colour index
46- 50 F5.2 mag i-[24] ?=- Subaru-IRAC i-[24] colour index
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Note (1): FX is X-ray flux in the 2-10keV band corrected for Galactic
absorption, and Fi is ΔλFλ in the i band corrected for
Galactic extinction.
Note (2): FX is the X-ray flux in the 2-10keV band corrected for Galactic
absorption, and F24 is λFλ, the flux density at 24um
in units of erg/s/cm2/Å.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 11-Feb-2019