The X-ray view of absorbed INTEGRAL AGN A. De Rosa On behalf of the INTEGRAL/AGN survey team

The broad-band INTEGRAL AGN sample (part of…) Source Type z* Observations exp(ks) IGR J12391-1610 Sy2 0.037 INTEGRAL/Chandra 200/3.2 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 135/9 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 …. .. … …. … From Bassani et al. 2006. 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 0.2-200 keV

Sample selection Absorbed objects i.e. NH>1022 cm-2 Type 2 AGN with F(20-100 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

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

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 J10404-4625 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

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

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

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 ~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 C=1 at 20 keV for INTEGRAL/XMM-Chandra-ASCA (Kirsch et al. 2005) SAX average values

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 4-40 1022 cm-2 would produce EW(Fe)=10-200 eV.

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

The sketch: a “grazing incidence” reflection Reflected continuum & Fe line Comptonized continuum Cold thick disc torus =100 scattered-thermal component NLR

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

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=0.2-0.9 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

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     

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…