(Obscured) Supermassive (Obscured) Supermassive Black HolesBlack Holes

Ezequiel Treister (IfA)Ezequiel Treister (IfA)Meg Urry, Shanil Virani, Priya Natarajan Meg Urry, Shanil Virani, Priya Natarajan

(Yale)(Yale)

Credit: ESO/NASA, the AVO project and Paolo Padovani

The Space Density of The Space Density of CT AGN and the XRBCT AGN and the XRB

Supermassive Black Supermassive Black Holes Holes

Credit: ESO/NASA, the AVO project and Paolo Padovani

Many obscured by gas and dustMany obscured by gas and dust

How do we know that?How do we know that?

Local AGN Unification

Explain Extragalactic X-ray “Background”

Compton Thick AGNCompton 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.

SwiftSwift INTEGRALINTEGRAL

ISDC

Swift Sources

Tueller et al. 2007

Significance Image, 20-50 keV

Deep INTEGRAL Survey (3 Msec)Deep INTEGRAL Survey (3 Msec)

Log N-Log SLog N-Log S

Treister et al. in prep.

Log N-Log SLog N-Log S

Treister et al. in prep.

Fraction of CT AGNFraction of CT AGN

Treister et al. in prep.

X-ray background does not constrain density of CT AGN

CT AGN and the XRBCT AGN and the XRB

CT AGN Space Density

Most likely solution

Gilli et al. 2007

Treister et al. in prep.

X-Ray Background X-Ray Background SynthesisSynthesis

Treister et al. in prep.

Contribution of CT AGN to the Contribution of CT AGN to the XRBXRB

Treister et al. in prep.

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.

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.

CT AGN at High RedshiftCT AGN at High Redshift

Treister et al. in prep.

How Many CT AGN?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.

• 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.

CT AGN Space Density CT AGN Space Density (L(Lxx>10>104545))

Treister et al. in prep.

Polletta+06

Treister et al. in prep.

Polletta+06

CT AGN Space Density CT AGN Space Density (L(Lxx>10>104545))

Treister et al. in prep.

Tozzi+06

Alexander+08

CT AGN Space Density CT AGN Space Density (L(Lxx>10>104444))

Treister et al. in prep.

Tozzi+06

Alexander+08

CT AGN Space Density CT AGN Space Density (L(Lxx>10>104444))

Treister et al. in prep.

Tozzi+06

Fiore+08

Risaliti+99

INTEGRAL

CT AGN Space Density CT AGN Space Density (L(Lxx>10>104343))

Treister et al. in prep.

INTEGRAL

Tozzi+06

Fiore+08

Risaliti+99

CT AGN Space Density CT AGN Space Density (L(Lxx>10>104343))

Treister et al. in prep.

Daddi+07

CT AGN Space Density CT AGN Space Density (L(Lxx>10>104242))

Treister et al. in prep.

Daddi+07

CT AGN Space Density CT AGN Space Density (L(Lxx>10>104242))

Mid-IR selection:- No NH

- Ref-dominated AGN- Interlopers

SMBHs Spatial DensitySMBHs Spatial Density

Natarajan & Treister, 2008

UMBHs Spatial DensityUMBHs Spatial Density

Natarajan & Treister, 2008

UMBHs Spatial DensityUMBHs Spatial Density

Natarajan & Treister, 2008

Self-RegulationSelf-Regulation

Momentum-driven Momentum-driven winds (Murray et winds (Murray et al. 2004).al. 2004).

Radiation Radiation pressure pressure (Haehnelt et al. (Haehnelt et al. 98)98)

Energy Driven Energy Driven Superwind (King Superwind (King 05)05)

Self-RegulationSelf-Regulation

Momentum-driven Momentum-driven winds (Murray et winds (Murray et al. 2004).al. 2004).

Radiation Radiation pressure pressure (Haehnelt et al. (Haehnelt et al. 98)98)

Energy Driven Energy Driven Superwind (King Superwind (King 05)05)

SummarySummary

• 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. (???)

• 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. (???)

Observed X-ray Observed X-ray “Background”“Background”

Frontera et al. (2006)

AGN in X-raysAGN in X-rays

Increasing NH

Photoelectric absorptionaffect mostly low energy emission making the observed spectrum look harder.

How to find high-z CT AGN NOW?How to find high-z CT AGN NOW?

X-rays?X-rays?

Tozzi et al. 2006

Trace rest-frame higher energies at higher redshifts Less affected by obscurationTozzi 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.

Extremely Red X-ray Objects Extremely Red X-ray Objects (ERXOs)(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:

1. very high redshift AGN – z > 6

2. very obscured AGN with old or dusty host galaxies at z~2-3

Probably a heterogeneous population?

ERXOs Examples in the ECDF-SERXOs Examples in the ECDF-S

Urry et al. in prep.

ECDF-S K band vs Hard X-ray FluxECDF-S K band vs Hard X-ray Flux

Urry et al. in prep.

* ERXOs

Confirming the ERXOs NatureConfirming 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.

• 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.

Sinfoni SpectroscopySinfoni Spectroscopy

Urry et al. in prep.

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

Fiore et al. 2008

How to find high-z CT AGN NOW?How to find high-z CT AGN NOW?

Mid-IR?Mid-IR? X-ray StackingX-ray Stacking

FF2424/F/FRR>1000>1000

FF2424/F/FRR<200<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)

NuSTARNuSTAR