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 J Sy INTEGRAL/Chandra 200/3.2
IGR J Sy INTEGRAL/Chandra /3.2
IGR J Sy INTEGRAL/Chandra /3.2
NGC Sy INTEGRAL/ASCA /40
ESO 103-G Sy INTEGRAL/XMM 44/12
IC 4518A Sy INTEGRAL/XMM 898/11.5
IGR J Sy INTEGRAL/XMM /13
IGR J Sy INTEGRAL/XMM /17
LEDA Sy INTEGRAL/XMM 135/9
IGR J Sy INTEGRAL/XMM /13
ESO Sy INTEGRAL/XMM /20
FRL Sy INTEGRAL/XMM /5(16)
4U Sy INTEGRAL/XMM 1042/25
IGR J Sy INTEGRAL/XMM /7
IGR J Sy INTEGRAL/XMM /6
IGR J Sy INTEGRAL/XMM /12
… … …. …
From Bassani et al and no more from XMM-AO6 large program .
(*) optical spectroscopy, Masetti et al. 2006
We applied in XMM AO7 to observe 22 AGN selected at E>10 keV by INTEGRAL to finally build a complete sample of 70 AGN in keV

3. Sample selection Absorbed objects i.e. NH>1022 cm-2
Type 2 AGN with F( keV) < 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*
LEDA Sy INTEGRAL/Chandra 200/
IGR J Sy INTEGRAL/Chandra 968/
IGR J Sy INTEGRAL/Chandra /
NGC Sy INTEGRAL/ASCA 594/
ESO 103-G35 Sy INTEGRAL/XMM 44/
IC 4518A Sy INTEGRAL/XMM 898/
IGR J Sy INTEGRAL/XMM 626/
* In 2-10 keV. In cgs

5. Thermal vs scattered scenario
Broad band observations are a powerful and unique tool to investigate the physics geometry of Innermost regions of AGN
Nature/geometry of the absorbing gas
IGR J
Absorption: NH
type 2 vs type 1 objects
CXRB synthesis study
Spectral slope and high energy cut-off: , Ec
Iron line together with the Compton reflection hump: EW, R,AFe
Compton thick vs Compton thin sources
Nature/geometry of the reflecting gas
Geometry at few Rg from the SMBH: AD? WSM?
Thermal vs scattered scenario
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-law+Ecut-off+Reflection+Fe 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/F[OIII] 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 r=0.0709
Is the absorbing gas able to produce the observed reflection hump?
For NH ~ 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 C=1 at 20 keV for INTEGRAL/XMM-Chandra-ASCA (Kirsch et al. 2005)
SAX average values

9. The Compton reprocessing components: II. The iron lines observations
The lines are due to cold iron and with narrow profile <0.3 keV
SAX
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 => increasing the EW
The NH values we found are in cm-2 would produce EW(Fe)= 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 ). 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
Reflected continuum
& Fe line
Comptonized continuum
Cold thick disc
torus =100
scattered-thermal component
NLR

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
SAX
NGC 788
IC 4518A
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. We observe different behaviour of the unabsorbed component
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: kT= keV - Scattered component:ASC/AIC fews%
We observe different behaviour of the unabsorbed component
II. Gradual upward curvature emerging below 4-5 keV BUT they are two peculiar case:
Starburst
SXV/SiXIV line
I. Sharp increase below 1-2keV

14. Conclusions 
All the object show significant cold absorption NH>1023 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?
Variability studies (that we completely miss in this analysis) need very deep INTEGRAL observations joint to multi-wavelength campaign with XMM (hoping to have success with the large program as proposed), Chandra and Swift.
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…