1. The spatial clustering of X-ray selected AGN at z~1 R. Gilli Istituto Nazionale di Astrofisica (INAF) Osservatorio Astronomico di Bologna and the XMM-COSMOS team G. Zamorani, M. Brusa, N. Cappelluti, F. Civano, A. Comastri, F. Fiore, G. Hasinger, V. Mainieri, T. Miyaji, J. Silverman et al.

2. On small scales (< 1 Mpc): What are the mechanisms triggering nuclear activity? Mergers (Hopkins +06), fly by (Cavaliere & Vittorini 00) or self regulating processes unrelated to galaxy interactions (Granato +04)? Any relation with star formation? On large scales (>1 Mpc): What is the location of AGN within the cosmic web? In which dark matter halos do they reside? What is their typical environment? Do obscured and unobscured AGN inhabit similar environments? A few questions (for AGN at all redshifts and luminosities)

3. Put figure from li for agn and starforming galaxies.. Local SDSS narrow-line AGN Star formation seems triggered by galaxy interactions, still no evidence for the majority of AGN Li +07 Projected cross-correlation function AGNStar forming galaxies

4. Shen +07 (SDSS) Optical QSOs at z>0 2QZ QSOs halo mass ~ constant ~ 3 10 12 M sun Even from the largest optical samples (2QZ, Porciani +06) there is still no clear evidence for any dependence of r 0 on luminosity 2QZ

5. Goals * Provide the best measurements to date of the correlation function of X-ray selected AGN * Provide for the first time a reliable measurement of the correlation function of obscured AGN up to z~1 (so far only SDSS results for local, narrow line, optically selected AGN) * Investigate the evolution with redshift and/or luminosity, AGN type * Compare with galaxy clustering, estimate host galaxies * Estimate masses of DM halos hosting X-ray nuclear activity * Estimate lifetimes of X-ray selected AGN * Estimate descendants of z~1 AGN

6. Large scatter (Vikhlinin +95, Basilakos +04, Gandhi +06, Puccetti +06, Miyaji +07, Basilakos +07). Dependence on flux/luminosity (eg Plionis +07)? Debated. Generation of random control samples problematic: uncertainties in the sensitivity maps. Also AGN redshift distribution is broad  radial dimension usually much larger than the transverse dimension Attempts to measure angular X-ray clustering Plionis +07

7. X-ray fields with measured 3D clustering Field Area/deg 2 S lim [cgs] N/deg 2 N(zspec)z med logL med Ref. NEP 81 2 10 -14 102200.444.7Mullis 03 BOOTES 9 5 10 -15 350 COSMOS 2 7 10 -16 9006201.043.8in prep. CLASXS 0.4 5 10 -16 15002301.143.8Yang 05 CDFS 0.1 5 10 -17 60001300.843.0Gilli 05 CDFN 0.13 2 10 -17 80002400.943.2 ’’ Surveys with different sensitivities sample different z and L x regimes Need large areas to cope with cosmic variance

8. XMM-COSMOS CDF-S/N CLASXS 0.1 deg 2 0.4 deg 2 2 deg 2 Hasinger +07

9. Distribution of XMM-COSMOS AGN on the sky 1822 X-ray sources 621 secure id and z-spec Spectroscopic follow-up with IMACS@Magellan and VIMOS@VLT (also SDSS) z-spec

10. Luminosity vs redshift distribution z-spec only

11. I-band magnitude vs redshift REFERENCE SAMPLE: 538 X-ray selected objects with I AB <23 and 0.2<z<3.0 z-spec z-phot For I AB <23 completeness is ~60% and the redshift distribution of z-spec is similar to that of the global XMM sample 

12. Redshift distribution of the reference sample: prominent spike at z~0.36 ~40 AGN with z=0.34-0.38 z~1 sample

13. Statistical description of LSS: the 2-point correlation function Spatial Correlation Function: excess probability over random of finding a source in dV 1 and another in dV 2 separated by a distance r Projected correlation function w(r p ): Allows to get rid of distortions in redshift space (i.e. peculiar velocities, redshift errors) π max =40 Mpc/h, random control sample contains >20000 objects: same ra,dec of real sources, redshifts resampled from the observed smoothed distribution

14. The projected correlation function All AGN r 0 = 8.4 ± 0.4 γ = 1.9 ± 0.1 No spike r 0 = 6.3 ± 0.6 γ = 1.9 ± 0.1 0.4<z<1.6 r 0 = 5.7 ± 0.7 γ = 1.8 ± 0.1 Most significant clustering measurement for X-ray selected AGN to date (~20σ Poisson errors ~10σ Bootstrap errors)

15. Clustering dependence on optical type / X-ray absorption / redshift BLAGN non-BLAGN High photon statisticsreference sample

16. Clustering dependence on: optical type r 0 = 7.2 ± 0.9 r 0 = 7.2 ± 0.8 γ = 2.0 ± 0.2 γ = 1.7 ± 0.2 X-ray absorption r 0 = 10.4 ± 0.5 r 0 = 6.5 ± 0.9 r 0 = 4.9 ± 1.7 γ = 1.9 ± 0.1 γ = 1.8 ± 0.2 γ = 2.4 ± 0.7 redshift r 0 = 6.9 ± 1.0 r 0 = 7.7 ± 0.4 r 0 = 5.1 ± 0.7 γ = 2.0 ± 0.2 γ = 1.8 ± 0.1 γ = 1.9 ± 0.2 No spike

17. The connection with host DM halos and galaxies Halo catalogs from the Millennium simulation (Springel et al. 2005) XMM-COSMOS AGN hosted by halos with M>3 10 12 Msun/h Their correlation length is similar to that of LIRGs and absorption line galaxies at the same redshift (Coil +04, Gilli +07)  moderately luminous z~1 AGN hosted by massive galaxies with stellar mass > 3 10 10 M sun (see also Nandra +07, Silverman +08) z~1 (0.4-1.6)

18. Clustering as a function of redshift XMM-COSMOS AGN cluster similarly to optically selected QSOs at the same redshifts Millennium halos CDFS

19. AGN lifetime (t Q ) from clustering For XMM-COSMOS AGN (Lx~10 44 erg/s; z~1): t Q ~ 3-6 10 8 yr The estimated lifetime is longer by a factor of a few than that of optically selected QSOs at the same redshift: this mainly reflects the higher space density of X-ray selected objects. Two basic assumptions: 1)QSOs reside in halos above a given halo mass threshold M min 2) there is one BH per halo known from CDM models and N-body simulations known from clustering AGN space density, known from LF Hosting halo density Halo lifetime; eg assumed to be Hubble time at z

20. A simple scenario for clustering evolution conserving scenario (Nusser & Davis 94, Fry 96 Moscardini +98): objects with a given bias simply evolve without merging along the density field b 2 (z)=ξ AGN /ξ DM b(z)= 1 + [b(0)-1]/D(z) The relics of the accreting SMBH observed in XMM-COSMOS will be hosted by local bright (L~L * ) ellipticals by z=0 z~1 sample Local ellipticals

21. Next: 1 deg 2 Chandra-COSMOS 890 X-ray objects fainter than XMM limit Probe clustering at lower luminosities Also with E-CDFS (~350 z-spec already in hand) Elvis +08 Puccetti +08 Civano +08 Fiore +08

22. Summary XMM-COSMOS provides 1) the most significant clustering measurement for X-ray selected AGN to date 2) the first significant measurement of clustering of obscured AGN beyond the local Universe No significant differences between clustering of obscured and unobscured AGN Presence of a significant redshift structure at z~0.36 which produces enhanced clustering signal at z<1 Clustering of XMM-COSMOS AGN at z~1 suggests they are hosted by massive galaxies, either passive or very actively starforming (LIRGs) Halo host masses are M>3 10 12 M sun, comparable to those obtained for optically selected QSOs at the same redshift Estimated lifetimes are longer by almost an order of magnitude than those estimated for optical QSOs  this reflects the higher space density of X-ray selected objects The relics of the accreting SMBH observed in XMM-COSMOS will be hosted by local bright (L~L * ) ellipticals by z=0