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(Obscured) Supermassive Black Holes. Ezequiel Treister ( IfA ) Meg Urry , Shanil Virani , Priya Natarajan (Yale), Julian Krolik (JHU), Eric Gawiser (Rutgers), Anton Koekemoer (STSCI). 3C-273: Bright Quasar. Credit: SDSS. NGC1068: Obscured AGN. Credit: SDSS.

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obscured supermassive black holes

(Obscured) Supermassive Black Holes

EzequielTreister (IfA)

Meg Urry, ShanilVirani, PriyaNatarajan (Yale),

Julian Krolik (JHU), Eric Gawiser (Rutgers), Anton Koekemoer (STSCI)

supermassive black holes
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

observed x ray background
Observed X-ray “Background”

Frontera et al. (2006)

agn i n x rays
AGN in X-rays

Photoelectric absorption

affect mostly low energy

emission making the

observed spectrum

look harder.

Increasing NH

compton thick agn
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.
slide10

Swift

INTEGRAL

slide11

ISDC

Swift Sources

Tueller et al. 2007

deep integral survey 3 msec
Deep INTEGRAL Survey (3 Msec)

Significance Image, 20-50 keV

log n log s
Log N-Log S

Treister et al. in prep.

log n log s euclidean
Log N-Log S (Euclidean)

Treister et al. in prep.

ct agn log n log s
CT AGN Log N-Log S

X-ray background does not constrain density of CT AGN

Treister et al. in prep.

ct agn and the xrb

Gilli et al. 2007

Most likely solution

CT AGN

Space Density

CT AGN and the XRB

Treister et al. in prep.

x ray background synthesis
X-Ray Background Synthesis

Treister et al. in prep.

contribution of ct agn to the xrb
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.

ct agn at high redshift
CT AGN at High Redshift

Treister et al. in prep.

how to find high z ct agn now
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

extremely red x ray objects erxos
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?

erxos examples in the ecdf s
ERXOs Examples in the ECDF-S

Urry et al. in prep.

ecdf s k band vs hard x ray flux
ECDF-S K band vs Hard X-ray Flux

* ERXOs

Urry et al. in prep.

confirming the erxos nature
Confirming the ERXOs Nature
  • No GALEX or GEMS counterparts
  • NIR spectroscopy crucial to determine the intrinsic nature

→ no ERXO has a measuredspectroscopicredshift

  • 4 ERXOs in ECDFS are bright enough to perform NIR spectroscopy.
  • Targeted with VLT/SINFONI IFU. Three sources observed.
sinfoni spectroscopy
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.

how to find high z ct agn now1
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

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.
ct agn space density l x 10 45
CT AGN Space Density (Lx>1045)

Polletta+06

Treister et al. in prep.

slide31

CT AGN Space Density (Lx>1045)

Polletta+06

Treister et al. in prep.

slide32

CT AGN Space Density (Lx>1044)

Alexander+08

Tozzi+06

Treister et al. in prep.

slide33

CT AGN Space Density (Lx>1044)

Alexander+08

Tozzi+06

Treister et al. in prep.

slide34

CT AGN Space Density (Lx>1043)

Fiore+08

Tozzi+06

Risaliti+99

INTEGRAL

Treister et al. in prep.

slide35

CT AGN Space Density (Lx>1043)

Fiore+08

Tozzi+06

Risaliti+99

INTEGRAL

Treister et al. in prep.

slide36

CT AGN Space Density (Lx>1042)

Daddi+07

Treister et al. in prep.

slide37

CT AGN Space Density (Lx>1042)

Daddi+07

Treister et al. in prep.

smbhs spatial density
SMBHs Spatial Density

Natarajan & Treister, 2008

umbhs spatial density
UMBHs Spatial Density

Natarajan & Treister, 2008

umbhs spatial density1
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

summary
Summary
  • Apparent lack of CT AGN in the local Universe compared to space density at high-z.
  • Number of CT AGN still roughly consistent with XRB, but can be increased ~4x
  • Strong decrease in the number of UMBHs -> Self regulation process. (???)