The%20X-ray%20view%20of%20absorbed%20INTEGRAL%20AGN

1
The X-ray view of absorbed INTEGRAL AGN

• A. De Rosa
• On behalf of the INTEGRAL/AGN survey team

2
The broad-band INTEGRAL AGN sample (part of)

• Source Type
  z Observations exp(ks)
• IGR J12391-1610 Sy2 0.037 INTEGRAL/Chandra 2
  00/3.2
• IGR J07565-4139 Sy2 0.021
  INTEGRAL/Chandra 968/3.2
• IGR J12026-5349 Sy2 0.028 INTEGRAL/Chandra
  728/3.2
• NGC 788 Sy2 0.014
  INTEGRAL/ASCA 594/40
• ESO 103-G35 Sy2 0.013
  INTEGRAL/XMM 44/12
• IC 4518A Sy2 0.016 INTEGRAL/XMM 898/11.5
• IGR J10404-4625 Sy2 0.024 INTEGRAL/XMM
  626/13
• IGR J18027-1455 Sy1 0.035 INTEGRAL/XMM
  2024/17
• LEDA168563 Sy1 0.029 INTEGRAL/XMM 13
  5/9
• IGR J07597-3842 Sy1.2 0.040
  INTEGRAL/XMM 837/13
• ESO 209-12 Sy1.5 0.040 INTEGRAL/XMM
  936/20
• FRL 1146 Sy1.5 0.031 INTEGRAL/XMM
  1041/5(16)
• 4U 1344-60 Sy1.5 0.0129 INTEGRAL/XMM 1042/25
• IGR J16482-3036 Sy1 0.0313 INTEGRAL/XMM
  1723/7
• IGR J16558-5203 Sy1.2 0.0054 INTEGRAL/XMM
  1509/6
• IGR J17418-1212 Sy1 0.0372 INTEGRAL/XMM
  1274/12
• . .. .

• We applied in XMM AO7 to observe 22 AGN selected
  at Egt10 keV by INTEGRAL to finally build a
  complete sample of 70 AGN in 0.2-200 keV

3
Sample selection

• Absorbed objects i.e. NHgt1022 cm-2
• Type 2 AGN with F(20-100 keV) lt 5 mCrab
• X-ray data available (XMM/Chandra/ASCA)
• We excluded sources with broad-band data already
  studied by BeppoSAX
• One well known source was retained (even if
  already studied by BeppoSAX) as a posteriori
  check for our analysis taht is affected by
  limitation of using non simultaneous X and
  soft-gamma rays measurements

• Our sample is representative of the populations
  of type 2 AGN observed by INTEGRAL above 10 keV

4
Our small Type 2 AGN sample

• Source Type z Observations
  exp(ks) Flux
• LEDA170194 Sy2 0.03
  INTEGRAL/Chandra 200/3.2 4.0
• IGR J07565-4139 Sy2 0.021
  INTEGRAL/Chandra 968/3.2 1.1
• IGR J12026-5349 Sy2 0.028 INTEGRAL/Chandra
  728/3.2 3.3
• NGC 788 Sy2 0.014 INTEGRAL/ASCA 594/40 1.
  4
• ESO 103-G35 Sy2 0.013 INTEGRAL/XMM 44/12
  7.9
• IC 4518A Sy2 0.016 INTEGRAL/XMM 898/11.5
  2.9
• IGR J10404-4625 Sy2 0.024 INTEGRAL/XMM 626/13.
  5 2.5
• In 2-10 keV. In 10-11 cgs

5
Broad band observations are a powerful and unique
tool to investigate the physics geometry of
Innermost regions of AGN
Absorption NH
Spectral slope and high energy cut-off ?, Ec
Iron line together with the Compton reflection
hump EW, R,????AFe
Soft X-ray excess kT, Asc/AIC
6
Spectral analysis. Broad-band fit

• Hard-X/soft-gamma components
• Absorbed power-law
  Fe K? line
• Absorbed power-law Ecut-off Fe
  K? line
• Absorbed power-lawEcut-offReflectionFe K? line
• Soft X-rays component
• Thermal emission
• Scattered power-law

7
The absorption

• The spectra of all sources are absorbed at low
  energies from a gas with column density in the
  range (4-40)1022 cm-2. This suggests/confirms a
  Compton thin nature for the sources.
• Other indicators of thick absorption support this
  evidence (e.g. FX/FOIII and X/FIR)
• We associated the absorption medium with the
  molecular torus

8
The Compton reprocessing components I. The
Reflection Hump
Test the correlation between the photon index and
R as proposed by Zdziarski et al. (1999) .. hard
to check! Possible with the larger
sample Correlation factor r0.0709
Is the absorbing gas able to produce the observed
reflection hump?

• For NH 1023-1024-1025 cm-2 the contribution of
  the torus at the flux at 30 keV is 8, 29 and 55
  per cent respectively (Ghisellini et al. 1994).
• Value of R higher than 2 can be 2 real or due
  to low flux state of the source or miscalibration
  between X-ray and gamma-ray instruments
• Cross-calibration constant measuerments on stable
  source (Crab) suggests C1 at 20 keV for
  INTEGRAL/XMM-Chandra-ASCA (Kirsch et al. 2005)

9
The Compton reprocessing components II. The
iron lines observations
The lines are due to cold iron and with narrow
profile ?lt0.3 keV
If the line is produced far away the central
source (TORUS?), at higher NH the continuum
photons will be absorbed BUT not the line photons
gt increasing the EW
The NH values we found are in 4-40 1022 cm-2
would produce EW(Fe)10-200 eV.
10
The origin of the Compton reflection features

• Question Is this component produced in the
  absorbing medium? R and EW are too high to be
  produced in the absorber with the measured NH
• Solution the absorber is not homogeneous and the
  thick medium covers a large fraction of the solid
  angle but not the line of sight (already proposed
  by Risaliti et al. 2002). Clumpy torus
• The alternative scenario a grazing incidence of
  the intrinsic continuum on the inner edge of the
  torus the high-energy photons

11
The sketch a grazing incidence reflection
12
The intrinsic continuum ? vs Ec

• All the values of Ec we measure (even if lower
  limits) suggest that this feature is a common
  property of Seyfert galaxies.
• In a pair of AGN the photon index is flatter than
  the average observed in Seyfert. Also including
  type 1 INTEGRAL AGN (Panessa et al. 2007). This
  evidence can be or real (as expected in the
  CXRB synthesis model, Gilli et al. 2007) or to
  the presence of complex absorption

An anti-correlation between photon index and Ec
is expected in a Comptonizzation model (Haardt et
l. 1997).. hard to check. Possible with larger
sample and deep observations
13
The soft X-ray excess
High resolution X-ray spectroscopy
(HETG-LETG/Chandra and RGS/XMM) associated this
component to photoionization of the NLR by the
primary continuum (Bianchi et al. 2006) or
thermal component due to starburst. Thermal
component kT0.2-0.9 keV - Scattered
componentASC/AIC fews
We observe different behaviour of the unabsorbed
component
14
Conclusions
?

• All the object show significant cold absorption
  NHgt1023 cm-2 in good agreement with the optical
  classification. All the sources are Compton thin
  (as confirmed by the ratio FX/OIII). We
  associated the absorber to the torus
• Compton reprocessing components (R Fe line)
  tell us that the reflection/absorbing medium can
  be one and the same even if with some particular
  constraint (not homogeneous, grazing incidence).
• .. but variability studies can help to
  investigate a different scenario R vs flux
  relation. Link the iron line properties with the
  reflection
• The value of the high energy cut-off we found
  suggests that it is a common property of Type 2
  AGN
• ...but correlations gamma vs flux, gamma vs
  Ecut-off have to be check
• We detect a soft excess in all the source. The
  origin seems to be different in different
  sources photoionized plasma and/or warm
  scattering medium

?
?
?
?
?
15
What we need now?

• Spend substantial amount of the INTEGRAL program
  on extragalactic field. This will allow to build
  a larger sample to search for correlations We
  stress that in 3th/2th IBIS ratio of detected AGN
  is 2