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

2. INTEGRAL (INTErnational Gamma-Ray Astrophysics Laboratory) INTEGRAL (INTErnational Gamma-Ray Astrophysics Laboratory) Astronomical satellite for observing the gamma-ray sky launched on October 17, 2002 The imager IBIS (Imager on Board the INTEGRAL Satellite) IBIS achieves an angular resolution of 12 arcmin over an energy range between 15 keV and 200 keV in the case of ISGRI (Integral Soft Gamma-Ray Imager)

3. 3 survey provided so far, 4 th on-going 3 survey provided so far, 4 th on-going http://www.integral.soton.ac.uk/projects/ibis_survey/data_access/access.html 2 nd catalogue (209 sources) + 1 st HE catalogue (2006) 1 st catalogue (2005) 126 sources 3 rd catalogue (2007) 421 sources 4 th LE and 2 nd HE catalogue on going 40000 pointed science windows 63 Ms Spans a duration of IJD = 1052 - 2688 1600+ days 1600+ days

4. The sky according to IBIS AGN distribution (131 sources) (131 sources)

5. Optical spectroscopy of most likely counterparts http://www.iasfbo.inaf.it/extras/IGR/main.html Telescopes: Loiano-Bologna Italy, South Africa, CTIO-Chile, La Silla Chile, CASLEO Argentina Sey1 Sey2 Narrow-Line Sey1 X-ray bright optically dull AGN A first catalogue of 60 AGN (Bassani et al. 2006) 82% Seyferts Sey2/Sey1=1 Gamma ray selection favours broad line sources Masetti et al. 2004, 2006 2008

6. The IBIS complete sample of AGNs The INTEGAL AGN complete sample 74 objects: 36 type 1 74 objects: 36 type 1 30 type 2 30 type 2 8 blazars/QSO 8 blazars/QSO The IBIS AGN total sample: 131 objects 58 type 1 (circles) 60 type 2 (squares) 13 blazars (triangles) + 21 AGN candidates

7. Broad-band observations Characterization of X-ray/gamma-ray spectra  Measurement of the column density  Definition of the primary (Γ, Cut-off energy and Reflection) X-ray Observations: SWIFT-XRT Chandra XMM (AO4, AO5, current AO C approved targets) ASCA BeppoSAX/MECS Gamma-ray Observations: INTEGRAL (IBIS) BeppoSAX (PDS), when available Primary Objectives: Secondary Objective:  study other source features (soft X-ray excess, soft emission lines)

8. INTEGRAL type 1 Seyferts: sample selection (Panessa et al. 2008) Sample of type 1 and 1.5 Seyfert galaxies with F(20-100 keV) > 5 mCrab Sample of type 1 and 1.5 Seyfert galaxies with F(20-100 keV) > 5 mCrab New XMM-Newton data (AO3/AO4) New XMM-Newton data (AO3/AO4) first data below 10 keV with this high sensitivity Nearby sources with z<0.054 Nearby sources with z<0.054 Representative of the INTEGRAL type 1 AGN population Representative of the INTEGRAL type 1 AGN population

9. INTEGRAL Type 2 Seyferts: sample selection (De Rosa et al. 2008) ● Absorbed objects i.e. N H >10 22 cm -2 ● Type 2 AGN with F(20-100 keV) < 5 mCrab ● 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 that 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

10. Broad band observations: the physics geometry of innermost regions of AGN Spectral slope and high energy cut-off: , E c Absorption: N H type 2 vs type 1 objects Nature/geometry of the absorbing gas Iron line together with the Compton reflection hump: EW, R,  A Fe CXRB synthesis study Nature/geometry of the reflecting gas Compton thick vs Compton thin sources Soft X-ray excess: kT, A sc /A IC Thermal vs scattered scenario Geometry at few Rg from the SMBH: AD? WSM? IGR J10404-4625

11. The NH distribution in the overall sample N H galactic N H intrinsic 37 < 22 36 > 22 ~50% BAT 55%

12. The NH distribution: type 1 vs type 2 N H galactic N H intrinsic 3 unabsorbed Sy2s: IGR J12415-5757 IGR J16024-6107 IGR J16024-6107 IGR J16351-5806 IGR J16351-5806

13. The Compton reprocessing components I. The Reflection Hump For N H ~10 23 -10 24 -10 25 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) 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 SAX average values Is the absorbing gas (the torus) able to produce the observed reflection hump?

14. The Compton reprocessing components: II. The iron line observations The lines are due to cold iron and with narrow profile  <0.3 keV If the line is produced far away the central source (TORUS?), at higher N H the continuum photons will be absorbed BUT not the line photons => increasing the EW The N H values we found are in 4-40 10 22 cm -2 would produce EW(Fe)=10-200 eV. SAX

15. 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 N H 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

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

17. 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. 2008). 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 al. 1997).. hard to check. Possible with larger sample and deep observations

18. IBIS SPECTRA 15-100 keV Photon index distribution of type 1 & 2 (59 objects) Weighted Mean =2.01±0.01 BAT =2.00±0.07 preliminary…

19. Photon index distribution: type 1 vs type 2 =2.07±0.02 BAT: =2.23±0.11 =1.96±0.02 BAT: =1.86±0.10 Sey 2s have harder X-ray spectra than Sey 1s BUT =2.06±0.02

20. Conclusions We presented the broad-band study of absorbed INTEGRAL AGN with the main goal to investigate the properties of the absorption/reflection and the intrinsic continuum characterization 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 1 and Type 2 broad line AGNs...but correlations gamma vs flux, gamma vs Ecut-off have to be checked The fraction of absorbed/unabsorbed sources is ~50%, in agreement with BAT results …but highly absorbed AGNs (SAX results by Risaliti 1999) are missing in our sample 

21. What we need now? INTEGRAL extragalactic fields are now available (2Ms on NEP) & the 4th cat/survey will double the number of AGN detected. This will allow us to build a larger sample to search for correlations and variability study. Variability studies (that we completely miss in this analysis) need very deep INTEGRAL observations joint to multi-wavelength campaign with XMM, Chandra and Swift.