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The evolution of SMBH from Hard X-ray surveys

The evolution of SMBH from Hard X-ray surveys. The XRB as a tracer of SMBH mass density Hard X-ray surveys: observational results Near-IR observations of hard X-ray sources Evidences of merging Conclusions and perspectives. Andrea Comastri (INAF – Osservatorio di Bologna – Italy).

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The evolution of SMBH from Hard X-ray surveys

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  1. The evolution of SMBH from Hard X-ray surveys • The XRB as a tracer of SMBH mass density • Hard X-ray surveys: observational results • Near-IR observations of hard X-ray sources • Evidences of merging • Conclusions and perspectives Andrea Comastri (INAF – Osservatorio di Bologna – Italy)

  2. Hard X-ray Surveys • Most direct probe of the super-massive black hole (SMBH) accretion activity recorded in the XRB spectral energy density • Chandra and XMM surveys: SMBH census is almost complete (integral)  obscured AGN make the bulk of the XRB • The light-up and evolution of obscured accreting SMBH is still largely unknown (differential)  XLF evolution of obscured AGN

  3. The deepest X-ray sky Chandra Surveys, 1 Ms exposures CDFS (Giacconi et al. 2002) HDFN (Brandt et al. 2001)

  4. The origin of the cosmic XRB A truly diffuse component not exceeding 10% of the observed flux (warm IGM, missing baryons …)may still be present in the soft (below 2 keV) X-ray band  the hard XRB (2-100 keV) is due to single sources (X-ray surveys, CMB argument) OBSCURED AGN

  5. SMBH mass density from XRB (Fabian & Iwasawa 1999)

  6. Where all the SMBH have gone ? N(L), N(z), efficiency, bolometric correction ?

  7. DEEP FIELDS: Redshift Distributions • CDFN, Barger et al. 2002 CDFS, Gilli 2003

  8. Cosmic Sheets Z=0.67 CDFS CDFN

  9. X-ray source clusteringYang et al. 2003 (astro-ph/0302137) • Hard X-ray sources more clustered than soft ones

  10. The same LSS is traced by both X-ray and near IR surveys Gilli et al. 2003 (astro-ph/0304177)

  11. Luminosity function: • Cowie et al. 2003 astro-ph/0301231 • Hasinger 2003 astro-ph/0302574

  12. Space density: • Cowie et al. 2003: rho_BH ~ 2x105 Hasinger 2003

  13. Deep Chandra surveys: limits • Small solid angle  lack of high z high L objects • Soft X-ray response  biased against highly obscured objects • Limited by faint optical counterparts and thus incomplete at high-z

  14. The Hellas2XMM survey • Wide and shallow: 3 deg2 (15 XMM public fields) ~30 sources/field, Fx>10-14  Bulk of the XRB • Rare and peculiar sources, avoid cosmic variance • Relatively “easy” multi-wavelength follow-up (ESO-VLT,3.6m, ATCA, VLA, TNG & Chandra)

  15. X/O -------- fX/fopt > 10 Likely to be highly obscured Undetected in the R-band at R=24-25 (shallow), even R>27-28 (deep) Constant fraction over a large range of fluxes Shallow surveys pick-up brightest sources  optical identification is possible

  16. Redshift from X-ray linesin the CDFN - R ~ 24 z= 1.15+-0.05

  17. 317 sources (Hellas2XMM + Lockman + CDFN + SSA13 -15 < logFx < -13.3 , 70% identified) Fiore et al. 2003

  18. Redshift distribution (Opt +stat. ids)

  19. The evolution of number and luminosity densities (Fiore et al. 2003) rho_BH ~ 4-6x105

  20. K-band observations of high X/0 Selection: • 11 sources • R > 24.5 • Flx(2-10) > 1.2 10-14 • VLT/ISAAC • 1 hour exp. in K • Seeing < 0.7 arcsec • Mag lim. ≈ 21

  21. ISAAC VLT K-band observations of high X/O 10/11 sources with a bright IR counterpart in the error box: ALL with R-K>5 ————————— Extremely red colors up to R-K~7 ! ————————— Extended morphologies Only two objects are compact (high z AGN ?) Elliptical, K=17.9, R-K=6.5 Pointlike, K=17.7, R-K>6.8 Cluster CD ?, K=18.7, R-K=6.0 Disky, K=18.4, R-K=5.8 (Mignoli et al, in prep.)

  22. High quality imaging • Surface brightness and effective radius BH mass estimate via FP and M(BH) vs. sigma relation NEED z Red=de Vaucouleurs Blue=exponential

  23. The X/O ratio is correlated with the R-K color:hope to get spectroscopic redshifts in the infrared

  24. Evidences of interacting SMBH

  25. Near IR imaging of hard X-ray sources:X-ray bright optically normal galaxies

  26. Concluding Remarks • The XRB appears to be dominated by low-z low-L objects • The SMBH mass density is almost equally accounted for by unobscured and obscured AGN (lower mass on average) • Obscured AGN are hosted by a wide variety of galaxy types • Redshifts for optically faint (high X/O) obscured sources urgently needed

  27. Broad Iron Lines at high z ?

  28. Comastri, Civano & Brusa (in prep.)

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