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The Cosmological properties of AGN in the
XMM-Newton Hard Bright Survey
Roberto Della Ceca INAF Osservatorio
Astronomico di Brera,Milan
On behalf of the XMM-Newton Survey Science
Centre
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Co-authors A. Caccianiga (INAF OABrera,
Milan, Italy) P. Severgnini (INAF
OABrera, Milan, Italy) T. Maccacaro (INAF
OABrera, Milan, Italy) H. Brunner (Max
Planck, Garching, Germany) F.J. Carrera
(IFCA, Santander, Spain) F. Cocchia
(INAF-OARoma, Italy) S. Mateos
(Leicester University, UK) M.J. Page
(MSSL, UK) J.A. Tedds
(Leicester University, UK)
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Why hard X-ray surveys are important
Most direct probe of the SMBH accretion activity
SMBH census
Constraints to models for the formation and
evolution of structures in the Universe
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A few key questions.
Which are the cosmological properties (e.g. XLF)
of the absorbed and unabsorbed AGN population?
Is the ratio absorbed/unabsorbed AGN a function
of Lx and/or z?
How the results compare with the Unification
models of AGN?
What about the heavily absorbed (NHgt1024 cm-2)
Compton Thick AGN?
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The XMM-Newton Bright Survey

• The XMM Bright Survey is aimed at selecting and
  spectroscopically identifying a large and
  statistically representative sample of bright
  (fxgt7x10-14 c.g.s) serendipitous XMM sources in
  two complementary energy bands.

0.5-4.5 keV energy band Bright Sample (BS)
4.5-7.5 keV energy band Hard Bright Sample
(HBSS)
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The XMM-Newton Bright Survey in pills
Della Ceca et al., 2004 Caccianiga et al., 2008
XMM fields used 237 Sources
400 (fx gt 7x10-14 cgs)
Identified 348 (87) (240 sources
from us) Covered Area (deg2) 28
Spectroscopic Classification
Type 1 AGN 70
Type 2 AGN
10 Other Extragalactic
4 Stars
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Optical and X-ray spectral analysis is possible
for almost all the sources in the XBS!!
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The X-ray sky above 5 keV the HBSS sample
Intrinsic NH vs. Intrinsic Lx
NH 4x1021
67 X-ray src 65 with ID Spectroscopic ID ?
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Intrinsic NH
Intrinsic Luminosity
40 Unabsorbed AGN 22 Absorbed AGN
NH 4x1021 ? Av2
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Lx-z plane
HBSS Sample
Redshift Distribution
Unabsorbed AGN 40 obj. Absorbed AGN 22
obj.
Luminosity Distribution
ltLog Lxgt 44.2
ltLog Lxgt 43.7
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De-evolved (z0) X-ray luminosity functions
Absorbed AGN vs. Unabsorbed AGN
NHlt4x1021
1/Vmax method (Schmidt, 1968), correcting for
the bias due to the photoelectric absorption.
40 obj
Absorbed AGN have a steeper XLF than the
unabsorbed ones
22 obj
4x1021ltNHlt1024
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Fraction of absorbed AGN in the HBS survey
Abs.AGN (4x1021ltNHlt1024 cm-2) --------------------
-------- All AGN (NHlt1024 cm-2)
Beckman et al., 2006
Bassani et al., 2006
Markwardt et al., 2006
HBSS
Lxgt3x1042 erg s-1
Sazonov et al., 2007
Absorbed AGN/All AGN (NHlt1024 cm-2)
Fraction 0.57?0.11
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Fraction of absorbed AGN in the HBS survey
Abs.AGN (4x1021ltNHlt1024 cm-2) --------------------
-------- All AGN (NHlt1024 cm-2)
Beckman et al., 2006
Bassani et al., 2006
Markwardt et al., 2006
HBSS
Lxgt3x1042 erg s-1
Sazonov et al., 2007
Very good agreement
Absorbed AGN/All AGN (NHlt1024 cm-2)

• From Integral/Swift
• Egt 10 keV
• fxgt10-11 cgs

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Fraction of absorbed AGN vs. Intrinsic Lx
First pointed out by Lawrence and Elvis,1982
In agreement with e.g. Ueda et al., 2003 La
Franca et al., 2005 Akylas et al.,
2006 Ballantyne et al., 2006
The fraction of obscured AGN decrease with Lx
From the HBSS sample (z0) using the best fit XLF
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Fraction of absorbed AGN vs. Intrinsic Lx
From Akylas et al., 2006
ltzgt0.8
ltzgt2.4
ltzgt1.2
ltzgt1.3
ltzgt1.5
From the HBSS sample (z0)
Redshift dependence?
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Fraction of obscured AGN vs. Intrinsic Lx
Rescaled to z0 using (1z)0.4 from (Treister
and Urry, 2006, Ballantyne et al., 2006)
The fraction of obscured AGN probably increase
with z
From the HBSS sample (z0)
See also La Franca et al., 2005
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Comparison with Unification models
The simplest unification scheme of AGN is ruled
out
HBSS
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Comparison with Unification models
Standard receding torus model Lawrence (1991)
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Comparison with Unification models
Modified receding torus model h ? L? with ?0.23
Simpson (2005) Honig and Beckert (2007)
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Comparison with optical samples
Fraction of optically Narrow line AGN Simpson
(2005)
Compton Thin AND Compton Thick
HBSS
Only Compton Thin AGN
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The intrinsic XLF of Compton Thick AGN
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The intrinsic XLF of Compton Thick AGN
XLFThick 2 x XLF4E21-E24
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The intrinsic XLF of Compton Thick AGN
XLFThick 4 x XLF4E21-E24
XLFThick XLF4E21-E24
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The intrinsic XLF of Compton Thick AGN
Independent measurements
Thick AGN from Sazonov et al., (2007) INTEGRAL
17-60 keV Sample ID rate 93 4 CT AGN
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The intrinsic XLF of Compton Thick AGN
Thick AGN from Daddi et al. (2007) rescaled to
z0 (SpitzerChandra) data
Independent measurements
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The intrinsic XLF of Compton Thick AGN
Independent measurements
Thick AGN from Fiore et al. (2008) rescaled to
z0 (SpitzerChandra) data ONE OF THE NEXT TALKS
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The intrinsic XLF of Compton Thick AGN
Very good agreement with independent
X-ray-infrared samples of CT AGN
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Compton Thin AGN vs. Compton Thick AGN
Compton Thick AGN NHgt1024 cm-2 -------------------
--------------------- Compton Thick AGN NHlt1024
cm-2
The fraction of CT AGN decrease with Lx
1.08?0.44
0.57?0.22
0.23?0.15
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Conclusions
We have discussed here the HBSS AGN sample.

• Absorbed AGN have a steeper XLF than the
  unabsorbed ones

• The intrinsic fraction of absorbed (Thin) AGN
  with Lxgt3x1042 cgs is 0.57?0.11. In excellent
  agreement with local samples of hard (gt10 keV)
  selected AGN at a flux limit of 10-11 cgs

• The fraction of abs. AGN is a function of Lx
  and, probably, of z

• Our results support the modified receding torus
  model

• We have derived, in an indirect way, the XLF of
  Compton Thick
• AGN and found that XLFThick 2 x
  XLF4E21-E24

• The fraction Thick AGN/Thin AGN decreases with
  Lx.

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Astro-ph/0805.1919
THANKS
The projects presented here have received partial
financial support from ASI, MIUR and INAF grants
over the last few years.