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(Obscured) Supermassive Black Holes

The Space Density of CT AGN and the XRB. (Obscured) Supermassive Black Holes. Ezequiel Treister (IfA) Meg Urry, Shanil Virani, Priya Natarajan (Yale). Credit: ESO/NASA, the AVO project and Paolo Padovani. Supermassive Black Holes. Many obscured by gas and dust. How do we know that?

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(Obscured) Supermassive Black Holes

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  1. The Space Density of CT AGN and the XRB (Obscured) Supermassive Black Holes Ezequiel Treister (IfA) Meg Urry, Shanil Virani, Priya Natarajan (Yale) Credit: ESO/NASA, the AVO project and Paolo Padovani

  2. Supermassive Black Holes Many obscured by gas and dust • How do we know that? • Local AGN Unification • Explain Extragalactic X-ray “Background” Credit: ESO/NASA, the AVO project and Paolo Padovani

  3. Compton Thick AGN • Defined as obscured sources with NH>1024 cm-2. • Very hard to find (even in X-rays). • Observed locally and needed to explain the X-ray background. • Number density highly uncertain. • High energy (E>10 keV) observations are required to find them.

  4. Swift INTEGRAL

  5. ISDC Swift Sources Tueller et al. 2007

  6. Deep INTEGRAL Survey (3 Msec) Significance Image, 20-50 keV

  7. Log N-Log S Treister et al. in prep.

  8. Log N-Log S Treister et al. in prep.

  9. Fraction of CT AGN X-ray background does not constrain density of CT AGN Treister et al. in prep.

  10. Gilli et al. 2007 Most likely solution CT AGN Space Density CT AGN and the XRB Treister et al. in prep.

  11. X-Ray Background Synthesis Treister et al. in prep.

  12. Contribution of CT AGN to the XRB Only 1% of the XRB comes from CT AGN at z≥2.  We can increase the # of CT AGN by ~10x and still fit the XRB. 50% 80% 90% Treister et al. in prep.

  13. CT AGN at High Redshift Treister et al. in prep.

  14. How Many CT AGN? • At low redshift (z<0.05), ~5-10 CT AGN from HEAO, BeppoSAX, INTEGRAL, Swift, etc. • At high redshift, candidates from X-ray and mid-IR selections. • Nothing at intermediate redshifts (z~0.5-1), when most of the XRB is emitted until EXIST, NuSTAR and Simbol-X.

  15. CT AGN Space Density (Lx>1045) Polletta+06 Treister et al. in prep.

  16. CT AGN Space Density (Lx>1045) Polletta+06 Treister et al. in prep.

  17. CT AGN Space Density (Lx>1044) Alexander+08 Tozzi+06 Treister et al. in prep.

  18. CT AGN Space Density (Lx>1044) Alexander+08 Tozzi+06 Treister et al. in prep.

  19. CT AGN Space Density (Lx>1043) Fiore+08 Tozzi+06 Risaliti+99 INTEGRAL Treister et al. in prep.

  20. CT AGN Space Density (Lx>1043) Fiore+08 Tozzi+06 Risaliti+99 INTEGRAL Treister et al. in prep.

  21. CT AGN Space Density (Lx>1042) Daddi+07 Treister et al. in prep.

  22. Mid-IR selection: • No NH • Ref-dominated • AGN • Interlopers CT AGN Space Density (Lx>1042) Daddi+07 Treister et al. in prep.

  23. SMBHs Spatial Density Natarajan & Treister, 2008

  24. UMBHs Spatial Density Natarajan & Treister, 2008

  25. UMBHs Spatial Density • Self-Regulation • Momentum-driven winds (Murray et al. 2004). • Radiation pressure (Haehnelt et al. 98) • Energy Driven Superwind (King 05) Natarajan & Treister, 2008

  26. Summary • The number of CT AGN in the local Universe can be constrained, thanks to Swift and INTEGRAL. • Number of CT AGN still roughly consistent with XRB, but can be increased by ~4x. • Strong decrease in the number of UMBHs -> Self regulation process. (???)

  27. Observed X-ray “Background” Frontera et al. (2006)

  28. AGN in X-rays Photoelectric absorption affect mostly low energy emission making the observed spectrum look harder. Increasing NH

  29. How to find high-z CT AGN NOW? X-rays? Trace rest-frame higher energies at higher redshifts  Less affected by obscuration Tozzi et al. claimed to have found 14 CT AGN (reflection dominated) candidates in the CDFS. Polletta et al. (2006) report 5 CT QSOs (transmission dominated) in the SWIRE survey. Tozzi et al. 2006

  30. Extremely Red X-ray Objects (ERXOs) • ERXOs are new class of X-ray emitters about which little is known • 7 found in CDFS (Koekemoer et al, 2004) • Defined by very red colors: R-K > 7 (Vega) • Given X-ray detection and very red optical-IR spectrum, either: • very high redshift AGN – z > 6 • very obscured AGN with old or dusty host galaxies at z~2-3 Probably a heterogeneous population?

  31. ERXOs Examples in the ECDF-S Urry et al. in prep.

  32. ECDF-S K band vs Hard X-ray Flux * ERXOs Urry et al. in prep.

  33. Confirming the ERXOs Nature • No GALEX or GEMS counterparts • NIR spectroscopy crucial to determine the intrinsic nature → no ERXO has a measured spectroscopic redshift • 4 ERXOs in ECDFS are bright enough to perform NIR spectroscopy. • Targeted with VLT/SINFONI IFU. Three sources observed.

  34. Sinfoni Spectroscopy Lx= 4.1x1044 erg/s  = 1.2±0.4 Lx= 2.6x1043 erg/s  = 1.5±0.4 Lx= 1.2x1043 erg/s  = 1.3±1.0 Urry et al. in prep.

  35. How to find high-z CT AGN NOW? Mid-IR? X-ray Stacking F24/FR>1000 F24/FR<200 • 4 detection in X-ray stack. Hard spectral shape, harder than X-ray detected sources. • Good CT AGN candidates. • Similar results found by Daddi et al. (2007) Fiore et al. 2008

  36. NuSTAR

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