1. Granada, May 27thThe X-ray Universe 2008 X-ray selected Type-2 QSOs: high luminosity in heavily obscured AGN Vincenzo Mainieri ESO G. Hasinger, M. Brusa, N. Cappelluti, K. Iwasawa, M. Salvato M. Bolzonella, A. Comastri, F. Fiore, R. Gilli, S. Lilly, J. Silverman, G. Zamorani + COSMOS -

2. Granada, May 27thThe X-ray Universe 2008 OUTLINE: COSMOS Survey Selection criteria Comparison with SDSS QSO-2 Comparison with MIR selection criteria Multi-wavelength properties Host galaxy properties Morphology Stellar masses Star formation rates Conclusions

3. Granada, May 27thThe X-ray Universe 2008 Why studying QSO-2? Quantifying the population of obscured quasars is essential for many applications: relating the present mass density of BH to the accretion history of the entire AGN population (e.g. Soltan 1982; Yu & Tremaine 2002; Marconi et al. 2004) understand the origin of the cosmic XRB (e.g. Comastri et al. 1995; Gilli et al. 2007) studying the effects of luminosity on AGN structure (e.g. Lawrence 1991; Urry & Padovani 1995; Hopkins et al. 2006; Hasinger 2008)

4. Granada, May 27thThe X-ray Universe 2008 QSO-2 selection criteria Radio: radio-loud QSO-2 have been know for decades from radio surveys, narrow line radio galaxies (see McCarthy 1993 for a review). They probably represents ~10% of the whole population Optical : candidates selected as objects with narrow ( FWHM<1000 km s -1 ) permitted emission lines and high ionization line ratios characteristic of non- stellar ionizing radiation (e.g. Djorgovski et al. 2001, DPSS) SDSS (Zakamska et al. 2003; Reyes et al. 2008): 887 QSO-2 with z<0.83 M B L[OIII] > 3 x 10 8 L SUN X-ray: hard X-ray spectra and high X-ray luminosity N H >10 22 cm -2 L X >10 44 erg s -1 (e.g. Norman et al. 2001, Dawson et al. 2001, Mainieri et al. 2002, Stern et al. 2002, Della Ceca et al. 2003, Perola et al. 2004, Szokoly et al. 2004, Barger et al. 2005, Mateos et al. 2005, Krumpe et al. 2008, ….) Mid-IR: the emission absorbed by the circumnuclear material is thermally re- emitted in the IR (e.g. Lacy et al. 2005, Stern et al. 2005, Martinez-Sansigre et al. 2006, Polletta et al. 2007, Daddi et al. 2008, Fiore et al. 2008)

5. Granada, May 27thThe X-ray Universe 2008 http://cosmos.astro.caltech.edu/ PI N. Scoville

6. Granada, May 27thThe X-ray Universe 2008 + MAMBO, CFHT, Bolocam and (future) others COSMOS major components (in order of appearance) : HST/ACS (I-band – 590 orbits – I(AB)~27) 2002-2003: Subaru imaging (~25 nights - b,v,r,i,z=26/27) VLA (265 hours – 24 μ Jy) GALEX deep (200 ks, AB~25) XMM-Newton (800 ks – 10 -15 cgs) 2004-2005: XMM-Newton (600 ks) VLT (540 hours) & Magellan (12+ nights) SPITZER-IRAC (200 hours - ~1 μ Jy) 2006: SPITZER-MIPS (200 hours - ~70 μ Jy ) Chandra (1.8 Ms) http://www.astro.caltech.edu/cosmos/ XMM-Newton PI: G. Hasinger soft 0.5-2.0 keV medium 2.0-4.5 keV hard 4.5-10.0 keV Cosmos Survey 2 deg 2 (PI: N. Scoville) http://cosmos.astro.caltech.edu ApJS special issue vol. 172

7. XMM-COSMOS 2 deg 2 -16 -15 -14 -13 Flux 2-10 keV (cgs) CDFN-CDFS 0.1deg2 Barger et al. 2003; Szokoly et al. 2004 EGS/AEGIS 0.5deg2 Nandra et al. 2006 HELLAS2XMM 1.4 deg2 Fiore et al. 20003 Cocchia et al. 2006 Champ 1.5deg2 Silverman et al. 2005 XBOOTES 9 deg2 Murray et al. 2005, Brand et al. 2005 Relative sizes of X-ray surveys SEXSI 2 deg2 Eckart et al. 2006 Area (see Brandt & Hasinger 2005 review (ARA&A 43, 827) E-CDFS 0.3deg2 Lehmer et al. 2005 ELAIS-S1 0.5deg2 Puccetti et al. 2006

8. Granada, May 27thThe X-ray Universe 2008 180 counts X-ray spectral analysis Fit statistic Cash-statistic with a binning of 1 count per bin: it recovers the input values better than  2 for faint sources (see also Tozzi et al. 2006 and Krumpe et al. 2008) Input models PL : powerlaw APL: powerlaw + intrinsic absorption at the redshift of the source Additional component to account for the photoelectric absorption due to the Galactic column density (N H Gal ~2.7 x 10 20 cm -2, Dickey & Lockman 1990) Soft excess: black body model or a double powerlaw (pcfabs) FeK  line: Gaussian centered at 6.4 keV rest-frame We have used the F-test to measure the significance for each spectral component (confidence threshold of 95%).

9. X-ray zoo [0.5-2] [2-4.5] [4.5-10] keV PL APL APL+soft APL+Fe

10. Granada, May 27thThe X-ray Universe 2008 QSO-2: X-ray selection criteria L X deabs [0.5-10 keV]>10 44 erg/s N H >10 22 cm -2 121 QSO-2 Probably the largest sample of X-ray selected QSO-2 : 14 (Krumpe et al. 2008) 6 (Mainieri et al. 2002) 10 (Szokoly et al. 2004) 6 (Mateos et al. 2005) SDSS: 887

11. Granada, May 27thThe X-ray Universe 2008 QSO-2 : N H distribution

12. Granada, May 27thThe X-ray Universe 2008 N H versus Redshift Statistical fluctuations in the X-ray spectrum can lead to spurious high values of N H at high redshift (e.g. Tozzi et al. 2006, Akylas et al. 2006). We find no trend of the N H values with redshift.

13. Granada, May 27thThe X-ray Universe 2008 25 arcsec ACS/HST z=0.1248 (SDSS spectrum) pexrav+gauss Compton-thick

14. Granada, May 27thThe X-ray Universe 2008 Stacked X-ray spectrum Only the rest-frame 2.1-10.1 keV band was used for each spectrum. Spectral binning was designed to match a fixed rest-frame 200eV intervals. The total accumulated counts are 4763.3 Assuming  =1.8 --> N H =(3.7± 0.6) 10 22 cm -2 EW(FeK  )~200 eV

15. Granada, May 27thThe X-ray Universe 2008 I AB =24 X-ray to optical flux ratios For I AB <24, 42% of the QSO-2 have spectroscopic redshifts. Above I AB =24, only photometric redshifts are available. 10% of the QSO-2 have X/O>10

16. Granada, May 27thThe X-ray Universe 2008 Photometric redshifts for AGN Improved templates, including hybrids of galaxy+AGN Photometry from >30 bands (SDSS, Subaru including IB, CFHT, J, K, IRAC)  = 0.017 Less than 10% of catastrophic errors Salvato et al., 2008

17. Granada, May 27th The X-ray Universe 2008 ESO - PI S. Lilly

18. Granada, May 27thThe X-ray Universe 2008 QSO-2 Redshift distribution 34 spectroscopic redshifts (28%) : 17 from IMACS/Magellan, 13 from zCOSMOS VIMOS/VLT and 4 from DEIMOS/Keck. 15 out of 34 (44%) do not show any sign of AGN activity from the optical spectra. z spec

19. Granada, May 27thThe X-ray Universe 2008 X-ray vs L[OIII] 5007 luminosity X-ray selected QSO-2 have lower L[OIII] compared to optically selected ones. Their L 2-10 /L [OIII] ratios are higher than opticaly seleted AGN : =0.6 for Seyfert-2 from Heckman et al. (2005) Their L 2-10 /L [OIII] ratios are consistent with what observed for local sample of X- ray selected AGN: =2.2 from Heckman et al. (2005) We measured L[OIII] 5007 for 6 QSO-2 and 112 AGN:

20. Granada, May 27thThe X-ray Universe 2008 X-ray vs optical QSO-2: optical colors Stellar locus z~0.8

21. Granada, May 27thThe X-ray Universe 2008 z=0-2 z=2-7 QSO-2: X-ray vs MIR selection Lacy’s wedge Stern’s wedge MIR selection: good (86% of X-ray QSO-2 inside Lacy’s wedge, 75% of X-ray QSO-2 inside Stern’s wedge) …but not perfect :high contamination by starburst (all z) and elliptical (z>2) galaxies

22. http://www.exp-astro.phys.ethz.ch/ZEST/ Host galaxy morphology Zurich Estimator of Strutural Type (Scarlata et al. 2007, ApJS, 172, 406) Five non-parametric diagnostics (asymmetry A, concentration C, Gini coefficient G, 2 nd order moment of the brightest 20% of galaxy pixels M 20, ellipticity  ) Sersic index n ZEST morphological type: 1 Early type 2 Disk 2.0 Bulge dominated disk (n>2.5) 2.1 … (1.25<n<2.5) 2.2 … (0.75<n<1.25) 2.3 Pure disk galaxy (n<0.75) 3 Irregular Since optical radiation from QSO-2 is heavily obscured there is no significant contamination from the bright central source

23. Granada, May 27th The X-ray Universe 2008 ZEST morphological classification for 29 QSO-2 Host galaxy morphology ELL SPIRAL IRR B/D Comparison sample of 36000 galaxies morphologically classified The majority the QSO-2 host galaxies are late type or irregular. Several of the irregular hosts can be described as undergoing merger activity or show tidal debris. SDSS QSO-2 (Zakamska et al. 2006): 6/9 de Vaucouleurs light profiles 1/9 disk dominated 2/9 marginal disk detection

24. Granada, May 27thThe X-ray Universe 2008 1.0 2.0 2.1 2.2 3.0 ACS/HST F814 W (5”x5”)

25. Granada, May 27thThe X-ray Universe 2008 1.4 GHz (2’x2’) Radio Loudness R=log(f 1.4GHz /f V ) Radio loudness defined in terms of the ratio of radio flux to broadband optical flux (e.g. Kellermann et al. 1989): assuming  r ~0.7 --> R~1.4 23/121 (~19%) radio loud QSO-2

26. Granada, May 27thThe X-ray Universe 2008 Type-2 QSO: Spectral Energy Distribution [0.1-20  m] The mean SED of our QSO-2 is consistent with the typical SED of Type-2 AGN (Schmitt et al. 1997) and rule out Type-1 SED in which L rises by ~2 orders of magnitude below 1  m (Elvis et al. 1994).

27. Granada, May 27thThe X-ray Universe 2008 Tyep-2 QSOs: stellar masses of the host galaxies The majority (75%) of QSO-2 have stellar masses above log M * ~10.5M SUN. This is similar to the characteristic mass for obscured AGN (Kauffmann et al. 2003) and radio-loud AGN (Best et al. 2005) in the SDSS. It is also consistent with the more general result that the fraction of galaxies hosting AGN increases with the stellar mass ( e.g. Silverman et al. 2008). Comparison sample of 22157 galaxies with 0.7<z<3.7 Estimate of the stellar masses Bolzonella et al. 2008: SED fitting to the multi-band photometry in COSMOS (U,B,V,g,r,I,z,K,3.6,4.5): BC03/CB07/M05 libraries + Chabrier/Kroupa IMF+ smooth exponential SFHs

28. Granada, May 27thThe X-ray Universe 2008 Tyep-2 QSOs: star formation rates of the host galaxies Comparison sample of 22157 galaxies with 0.7<z<3.7 Estimate of the stellar masses Bolzonella et al. 2008: SED fitting to the multi-band photometry in COSMOS (U,B,V,g,r,I,z,K,3.6,4.5): BC03/CB07/M05 libraries + Chabrier/Kroupa IMF+ smooth exponential SFHs The host galaxies of QSO-2 have ongoing star formation higher that the comparison sample of galaxies. This is consistent with the host galaxies be manly late types or irregulars. 60% of QSO-2 have SFR in range 1-1000 M SUN /yr.

29. Granada, May 27thThe X-ray Universe 2008 Conclusions We have selected a large (121) sample of QSO-2 based on their X-ray properties (N H >10 22 cm -2 & L X >10 44 erg/s) on a wide redshift range: 0.6<z<3.7 Their L 2-10 /L [OIII] ratios are higher than optically selected AGN-2. Different selection methods (radio, mid-IR, optical, X-ray) of QSO-2 are affected by different selection effect therefore select different samples. The majority the QSO-2 host galaxies are late type or irregular. Several can be described as undergoing merger activity or show tidal debris. The mean SED of our QSO-2 is consistent with the typical SED of Type-2 AGN. The majority (75%) of QSO-2 host galaxies have stellar masses above log M * ~10.5M SUN and have ongoing star formation, ~100 M SUN /yr