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The Evolution of AGN Obscuration

The Evolution of AGN Obscuration. Ezequiel Treister (ESO) Meg Urry (Yale) Julian Krolik (JHU) Shanil Virani (Yale) Eric Gawiser (Rutgers). broad lines. blazars, Type 1 Sy/QSO. The AGN Unified Model. Urry & Padovani, 1995. radio galaxies, Type 2 Sy/QSO narrow lines.

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The Evolution of AGN Obscuration

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  1. The Evolution of AGN Obscuration EzequielTreister (ESO) Meg Urry (Yale) Julian Krolik (JHU) ShanilVirani (Yale) Eric Gawiser (Rutgers)

  2. broad lines blazars, Type 1 Sy/QSO The AGN Unified Model Urry & Padovani, 1995

  3. radio galaxies, Type 2 Sy/QSO narrow lines The AGN Unified Model Urry & Padovani, 1995

  4. 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

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

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

  7. X-ray Background XRB well explained using a combination of obscured and unobscured AGN. # w NH > 1023 cm-2 still uncertain. • Setti & Woltjer 1989 • Madau et al. 1994 • Comastri et al. 1995 • Gilli et al. 1999,2001 • And others… Treister & Urry, 2005

  8. COSMOS E-CDF-S • XMM+ChandraCoverage • 2 deg2 • FX=~10-15erg cm-2s-1 • ~1100 X-ray sources • Chandra Coverage • 0.25 deg2 • FX=~10-16erg cm-2s-1 • ~800 X-ray sources Multiwavelength Surveys • HardX-rayspenetrate most obscuration • Energy re-radiated ininfrared • High resolutionopticalseparates host galaxy, constrains redshifts

  9. Extended Chandra Deep Field South(optical)

  10. Extended Chandra Deep Field South(x-rays)

  11. Hardness Ratio vs. Luminosity More unobscured AGN at high X-ray luminosity? Treister et al in prep.

  12. NH vs. Luminosity In general good agreement between optical and X-ray classification. Treister et al in prep.

  13. NH vs. Redshift Obscuration increases with redshift? Or selection effect due to X-rays K correction? Treister et al in prep.

  14. HST ACS color image (0.3% of GOODS)

  15. HST+Spitzer color image (0.3% of GOODS)

  16. IR Fraction vs Flux AGN are bright IR sources! Treister et al 2006

  17. IR Luminosity Distribution On average, AGN are ~10x brighter than normal galaxies For fainter AGN, the host galaxy makes a significant contribution Treister et al 2006

  18. X-Ray to mid-IR Ratio Significant separation between obscured and unobscured sources. Unobscured QSO Template Smaller separation at shorter wavelength (host galaxy) and largest at longer wavelength (self-absorption). Obscured QSO Template Treister et al in prep.

  19. X-Ray to mid-IR Ratio More separation at lower luminosities. Change in the opening angle with luminosity? Larger opening angle, ie less self-absorption. Treister et al in prep.

  20. Infrared Background AGN (+ host galaxy) contribute ~3-10% of the total extragalactic background light Treister et al 2006

  21. NH Distribution:What do we know so far? • More obscured AGN at low luminosity (Steffen et al. 2003, Ueda et al. 2003, Barger et al. 2005, Akylas et al. 2006) • More obscured AGN at high-z? (Ueda et al. 2003: No, La Franca et al. 2005: yes, Ballantyne et al. 2006: yes) • Problems: • Low number of sources • Selection effects: • - X-ray selection (missed obscured sources) • - Optical incompleteness (no redshifts) • - X-ray classification: “K correction”

  22. Meta-Survey • 7 Surveys, • 2341 AGN, 1229 w Ids • 631 Obscured • (no broad lines) • 1042<Lx<1046, 0<z<5 Treister & Urry, 2006

  23. Total effective area of meta-survey Treister & Urry, 2006

  24. Ratio vs Redshift Treister & Urry, 2006

  25. Ratio vs Redshift Treister & Urry, 2006

  26. Ratio vs Redshift Treister & Urry, 2006

  27. Ratio vs Redshift Key input: Luminosity dependence of obscured AGN fraction. See also: La Franca et al. 2005 Ballantyne et al. 2006 Akylas et al. 2006 Treister & Urry, 2006

  28. Ratio vs Luminosity Treister & Urry, 2006

  29. Ratio vs Luminosity Treister & Urry, 2006

  30. Ratio vs Luminosity Hasinger et al. Treister & Urry, 2006

  31. The AGN Unified Model Urry & Padovani, 1995

  32. Low L • GOODS: North+South fields • 10 unobscured AGN • All Spitzer 24 µm photometry • 8 with GALEX UV data • High L • SDSS DR5 Quasar sample • 11938 quasars, 0.8<z<1.2 • 192 with Spitzer 24 µm photometry • 157 of them with GALEX UV data Torus StructureSample • Completely unobscured AGN • Narrow redshift range, 0.8<z<1.2 • Wide range in luminosity • Data at 24 µm from Spitzer • Mid L • COSMOS • 19 unobscured AGN • 14 Spitzer 24 µm photometry • All with GALEX UV data

  33. Torus Structure Bolometric luminosity constructed from NUV to mid-IR. No change in NUV/Bol ratio with luminosity! Treister et al. 2008

  34. Torus Structure Change in 24 µm/Bol ratio with luminosity! • Lower ratio at high L • Consistent with larger opening angles at higher luminosities. Treister et al. 2008

  35. Fraction of Obscured AGN Similar luminosity dependence as found on X-ray surveys. • Higher values from • fIR/fbol method. • Obscured AGN • missed by X-ray • surveys. Treister et al. 2008

  36. 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.

  37. INTEGRAL Survey • PIs: MegUrry, ShanilVirani, Ezequiel Treister • Exp. Time (Msec): 0.7 (archive)+1.5 (2005)+ 1 (2008). Deepestextragalactic INTEGRAL survey • Field: XMM-LSS (largestXMM field) • Flux limit: ~4x10-12ergs cm-2 s-1(20-40 keV) • Area: ~1,000 deg2 • Sources: ~20 • Obscured AGN: ~15 (~5 Compton-thick)

  38. MCG-02-08-014 INTEGRAL Mosaic (2.2 Ms) Significance Image, 20-50 keV

  39. MCG-02-08-014 • z=0.0168 • Optical class: Galaxy • IR source (IRAS) • Radio source (NVSS) • Narrow line AGN • (based on OIII emission) • No soft X-rays (ROSAT) • Good CT AGN candidate

  40. Space Density of CT AGN X-ray background does not constrain density of CT AGN Treister et al, submitted

  41. Treister & Urry, 2005 CT AGN and the XRB XRB Intensity HEAO-1 +40% Treister et al, submitted

  42. Treister & Urry, 2005 Gilliet al. 2007 CT AGN and the XRB XRB Intensity HEAO-1 Original HEAO-1 +10% HEAO-1 +40% Treister et al, submitted

  43. Treister & Urry, 2005 Gilliet al. 2007 Most likely solution CT AGN Space Density CT AGN and the XRB XRB Intensity HEAO-1 Original HEAO-1 +10% HEAO-1 +40% Treister et al, submitted

  44. X-ray Background Synthesis

  45. NH Distribution

  46. Summary • AGN unification can account well for the observed properties of the X-ray background. • AGN are luminous infrared sources, but contribute ~5% to extragalactic infrared background • The obscured AGN fraction decreases with increasing luminosity. • Ratio of IR to Bolometric luminosity in unobscured AGN suggest this is due to a change in opening angle. • The obscured AGN fraction increases with redshift as (1+z)0.4. • Survey at high energies starts to constrain the spatial density of CT AGN.

  47. SBH Spatial Density Natarajan & Treister, in prep

  48. XRB Intensity

  49. Ratio vs Luminosity Treister & Urry, 2006

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