Boston, November 2006 Extragalactic X-ray surveys Paolo Tozzi Spectral analysis of X-ray sources in the CDFS

0.3-1 keV 1-3 keV 3-7 keV Rosati et al National Geographic, Dec 2002 Detailed spectral analysis of X-ray sources Tozzi, Gilli, Mainieri et al. 2006, A&A, 451, 457

Deep X-ray Surveys: some open issues The distribution of intrinsic absorption among AGN Detection of Compton-Thick AGN The unresolved fraction of the XRB at high energies

Compton thick candidates

N H vs redshifts for the whole sample

Detected fraction as a function of N H and z Sampling different luminosity and spectral population at different z Selection effects are relatively easy to model in the X-ray band z < < z <1.5 z > 1.5

N H histogram corrected for completeness Corrected for completeness and sources outside the detectability region ~ 23.1 dispersion = 1.1 5% C-thick (14 reflection +4 sources N H > cm -2 ) density ~ deg -2 in agr w XRB model by Gilli, Comastri, Hasinger (2006)

N H distribution vs Optical Type

Whole sample (321) Cthick candidates (14) Consistent with evolutionary sequence: pre-QSO phase C-thin absorbed QSO high z) unobscured QSO activity quiescent spheroidal galaxy Alexander et al. 2005; Stevens et al Model: Granato et al Part of the missing XRB is from intermediate z strongly absorbed moderate luminosity, possibly C-thick sources, in a secondary, relatively low-z phase of accretion (see “downsizing” or anti- hierarchical behaviour) Whole sample (321) QSOII (44)

Missing XRB: N H = cm z=0.8 ~50% not resolved yet for E> 5 keV (Worsley et al. 2004, 2005) The unresolved fraction increases with the energy band

Compute the contribution of the absorbed sources to the XRB N H > cm -2 N H > cm -2

Worsley et al This work After computing the skycoverage according to the spectral shape of each source

CONCLUSIONS Detailed X-ray Spectral Analysis of faint X-ray sources: Towards an universal distribution of intrinsic absorption (selection effects can be easily modelled in X-rays) >~80% of the AGNs agree with simple unification models (TypeI/TypeII Unobscured/Obscured corr.) Evidence for strongly absorbed, C-thick z~1, and a substantial QSOII population at z>~2 Part of the missing XRB is already observed in agreement with most recent XRB synthesis models

C-thick candidates in IRAC/MIPS colors

Use secure spectral identifications in CDFS and CDFN Norman et al galaxies with good spectra in the CDFS and emission line ratios consistent with starbursts or normal galaxies give the X-ray priors. A Bayesian approach allows us to identify 74 galaxies in the CDFS and 136 in the CDFN (2 Ms)

SFR densities C ompilation from Tresse et al. 2002: Gallego et al (H ) Gronwall 1999 Hopkins et al Pascual et al Tresse et al Sullivan et al Lilly et al Lines from 60  m Saunders et al. 1990, Takeuchi et al Norman et al XLF consistent with a PLE ~ (1+z) 2.7 Consistent with an evolution of SFR  (1+z) 2.7 for 0<z<1. XLF of Star Forming Galaxies is a goal for future X-ray missions (Con-X, XEUS)

Daddi et al K20 survey

IR selected galaxies at z~2 with massive SF Daddi et al Stacked image of 23 BzK galaxies; HR< 2sigma ; L 2-10 ~10 42 erg/sec SFR ~ 170 M ⊙ yr -1 (4 higher than LBG). SFRD of 0.04 M ⊙ /yr/Mpc 3 We are witnessing the massive spheroid formation epoch (the peak of just the low-z tail?) Soft Hard

The evolution of the obscured fraction with redshift This work Ueda et al. 2003

Average N H artificially increases towards high-z Tozzi, Gili, Mainieri et al N H ~ cm and 80 net counts

Ueda et al 2003 Hasinger et al Luminosity dependent density evolution: downsizing or anti-hierarchical behaviour

Extended CDFS PI N. Brandt ~1000 sources (Lehmer et al. 2005) 1Ms + 4 X 240 ks

AGN Contribution to the hard XRB CDFS (1Ms): XRB(S> 4.5 × ) = (1.70 ± 0.15) × erg s -1 cm -2 deg -2 90% resolved in keV 93% resolved in 2-8 keV AGN contribution 83% in keV 95% in 2-8 keV (Bauer et al. 2004) CDFN (2Ms): XRB(S> 2 × ) = (2.07 ± 0.15) × erg s -1 cm -2 deg -2

Worsley et al. 2004; 2005 Missing XRB: N H = cm z=0.8 ~50% not resolved yet for E> 5 keV (Worsley et al. 2004, 2005) The unresolved fraction increases with the energy band

Compute the contribution of the absorbed sources to the XRB

Worsley et al This work After computing the skycoverage according to the spectral shape of each source