INFRARED SELECTED HIGHLY OBSCURED QSO

1. INFRARED SELECTEDHIGHLY OBSCURED QSO C. Feruglio (INAF-OAR) & F. Fiore, E. Piconcelli, R. Maiolino, + many others (OABo, UniBo, MPE, ASDC)

2. High MIR/O High luminosity obscured AGN SAMPLE SELECTION High MIR/Optical flux ratio indicates the presence of an obscured AGN Strong correlation of MIR/O with 24 um luminosity for moderately obscured AGN Recalls the correlation between X/O and L(2-10 keV) for moderately obscured AGN selected in X-rays Filled symbols=moderately obscured AGN X-ray samples; GOODS-MUSIC, ELAIS-S1, HELLAS2XMM (Pozzi et al 2007)

3. MIR/O correlated with R-K color Bimodal distribution of R-K for sourcess with MIR/O>1000, separate population SAMPLE SELECTION (Fiore et al 2007) This selection is equilvalent to SFR (IR) >> SFR (UV)

4. 0.3-1.5 keV 1.5-4 keV F24um/FR >1000 R-K>4.5 The stack produces a detection in both soft and hard bands 0.3-1.5 keV 1.5-4 keV F24um/FR <100 R-K>4.5 Detection only in 0.3-1.5 keV (Fiore et al 2007)

5. A new population of CT AGN Using the observed counts rate and hardness ratios we evaluated the fraction of highly obscured AGN (logNH>24) in the samples Assuming a reasonable LIR/LX ratio, a flat NH distribution from logNH=24-26 and a reflection component =1% of the direct one Stack of Chandra images excluding X-ray detections Fiore et al. 2007

6. Elais S1 Elais N1 Elais N2 Lockman Hole XMM-LSS HIGH MIR/O SWIRE SOURCES • Large area (50 deg2) with sensitive IR (Spitzer) and optical data, suitable for searching for type2 QSO • Small fraction covered with shallow X-ray observations below 10 keV • ~ 30% of the high MIR/O sources with XMM/Chandra coverage are detected below 10 keV Blue circles = XMM pointings; Red polygons = Chandra ACIS-I and ACIS-S pointings

7. SWIRE SWIRE highly obscured QSO About 30 SWIRE sources with MIR/O > 2000 Flux(24um) > 2 mJy and R-mag(3.6um)>4.5 SWIRE CDFS X-ray sources

8. Bright MIPS sources Fl 24 um > 4 mJy with faint optical counterparts (R>24)

9. IRAS 09 SDSS spectrum The template obscured QSO: IRAS 09104+4109 • Template Compton-thick QSO • High L(IR)/Lx ratio • No PAH emission features in IRS spectrum • IR SED dominated by the AGN Abell 112690#75 (Pozzi et al 2007) IRAS 09

10. log(L/ L 2-10 keV ) l rest The template obscured QSO: IRAS 09104+4109 L(2-10 keV) = 8.8 1044 cgs Use the observed SED and L(24 um) to evaluate L(2-10 keV) for high MIR/O sources

11. Candidate highly obscured QSO targets for Simbol-X SW110013.92+581034.9 SW163515.61+405607 z = 1 L (24 um) = 3.2 1045 L (2-10 keV) = 1.1 1044 z = 1.5 L (24 um) = 5.8 1045 L (2-10 keV) = 4.7 1044 IRAS09104+4109 SWIRE

12. Simbol-X view ofSW110013.92+581034.9z=1 • Binned, bkg-subtracted, 200 ks spectrum; • A typical Compton-thick source spctrum is assumed : NH = 2 1024 cm-2 , Gamma=1.8, EW(Fe Ka )= 1keV • Normalization of the reflected vs transmitted component : A_refl/A_trans =0.2 (e.g. Circinus, Matt et al. 99) L(2-10 keV) = 1.1 1044 cgs intermediate luminosity AGN F(2-10 keV) = 7.1 10 -15 cgs F(20-40 keV)=1.7 -14 cgs

13. Simbol-X view ofSW163515.61+405607 z=1.5 The same model with T_exp=300 ks L(2-10 keV)=3.03 1044 , F(2-10 keV)=1.07 10 -14 cgs, F(20-40 keV)=1.7 10-14 cgs SX allows to constrain NH for the most heavily obcured AGN up to z=2 with ~ 30% error at 2 sigma

14. Conclusions • We selected a sample of ~ 30 candidate type 2 QSOs using deep IR and optical photometry in the SWIRE fields • These are going to be targets of several present and future observatories (Chandra, XMM, Herschel, ALMA...) • We used the SED of IRAS09104+4109 and Abell112690 to evaluate the intrinsic X-ray luminosity • Assuming NH typical of a Compton thick AGN we obtained simulations of SX observationsThe simulations show that the sources are detected up to 60 keV and the 90% uncertainty on NH is < 30% • SX Observations of this sample of IR selected QSOs will allow us to : 1) obtain a complete census of SMBH up to z 1.5-2 ; 2) obtain a well constrained NH distribution