the evolution of agn obscuration
DESCRIPTION
The Evolution of AGN Obscuration. Ezequiel Treister (ESO) Meg Urry (Yale) Julian Krolik (JHU) Shanil Virani (Yale) Priya Natarajan (Yale). Host Galaxy. Active Galactic Nucleus (AGN). supermassive black hole actively accreting matter 1-1000 x galaxy luminosity from few lt-hrs. - PowerPoint PPT PresentationTRANSCRIPT
The Evolution of The Evolution of AGN ObscurationAGN Obscuration
Ezequiel Treister (ESO)Ezequiel Treister (ESO)Meg Urry (Yale)
Julian Krolik (JHU)Shanil Virani (Yale)
Priya Natarajan (Yale)
Active Galactic Nucleus Active Galactic Nucleus (AGN)(AGN)
supermassive black hole
actively accreting matter
1-1000 x galaxy luminosity from few lt-hrs
Host Galaxy
The AGN Unified ModelThe AGN Unified Model
blazars, Type 1 Sy/QSO
broad lines
Urry & Padovani, 1995
The AGN Unified ModelThe AGN Unified Model
radio galaxies, radio galaxies, Type 2 Sy/QSOType 2 Sy/QSO
narrow linesnarrow lines
Urry & Padovani, 1995
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”
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.
X-ray BackgroundX-ray Background
Treister & Urry, 2005
XRB well explained using a combination of obscured and unobscured AGN.
•Setti & Woltjer 1989•Madau et al. 1994•Comastri et al. 1995•Gilli et al. 1999,2001•And others…
# w NH > 1023 cm-
2
still uncertain.
What do we know so What do we know so far?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:Problems:• Low number of sources• Selection effects: - X-ray selection (missed obscured sources) - Optical incompleteness (no redshifts) - X-ray classification: “K correction”
Meta-SurveyMeta-Survey
• 7 Surveys, • 2341 AGN, 1229 w Ids• 631 Obscured (no broad lines)• 1042<Lx<1046, 0<z<5
Treister & Urry, 2006
Total effective area of meta-Total effective area of meta-surveysurvey
Treister & Urry, 2006
Ratio vs RedshiftRatio vs Redshift
Treister & Urry, 2006
Ratio vs RedshiftRatio vs Redshift
Treister & Urry, 2006
Ratio vs RedshiftRatio vs Redshift
Treister & Urry, 2006
Ratio vs RedshiftRatio vs Redshift
See also:La Franca et al. 2005Ballantyne et al. 2006Akylas et al. 2006
Key input: Luminosity dependence of obscured AGN fraction.
Treister & Urry, 2006
Ratio vs LuminosityRatio vs Luminosity
Treister & Urry, 2006
Ratio vs LuminosityRatio vs Luminosity
Treister & Urry, 2006
Ratio vs LuminosityRatio vs Luminosity
Treister & Urry, 2006
Hasinger et al.
The AGN Unified ModelThe AGN Unified Model
Urry & Padovani, 1995
obsc
obsc
bol
IR
f
f
L
L
1
A Changing Torus?A Changing Torus?A change in the IR/NUV flux ratio may indicate a change in torus geometry.
~2x
Granato & DaneseTorus model
Torus StructureTorus StructureSampleSample
Completely unobscured AGNNarrow redshift range, 0.8<z<1.2Wide range in luminosityData at 24 µm from Spitzer
High LHigh 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
Low LLow L•GOODS: North+South fields•10 unobscured AGN•All Spitzer 24 µm photometry•8 with GALEX UV data
Mid LMid L•COSMOS•19 unobscured AGN•14 Spitzer 24 µm photometry•All with GALEX UV data
Torus StructureTorus StructureBolometric luminosityconstructed from NUVto mid-IR.
No change in NUV/Bolratio with luminosity!
Treister et al, ApJ submitted.
Torus StructureTorus Structure
Change in 24 µm/Bolratio with luminosity!
Lower ratio at high L Consistent with larger opening anglesat higher luminosities.
Treister et al, ApJ submitted.
Fraction of Obscured AGNFraction of Obscured AGNSimilar luminositydependence as foundon X-ray surveys.
Higher values from fIR/fbol method. Obscured AGNObscured AGNmissed by X-raymissed by X-raysurveys. Detectedsurveys. Detectedin mid-IR?in mid-IR?
Treister et al, ApJ submitted.
HST ACS color image (0.3% of GOODS)
HST+Spitzer color image (0.3% of GOODS)
IR Fraction vs FluxIR Fraction vs Flux
Treister et al 2006
AGN are bright IR sources!
IR Luminosity IR Luminosity DistributionDistribution
Treister et al 2006
On average, AGN are ~10x brighter than normal galaxies
For fainter AGN, the host galaxy makes a significant contribution
Infrared BackgroundInfrared Background
Treister et al 2006
AGN (+ host galaxy) contribute ~3-10% of the total extragalactic background light
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.
INTEGRAL SurveyINTEGRAL Survey
• PIs: Meg Urry, Shanil Virani, Ezequiel Treister• Exp. Time (Msec): 0.7 (archive)+1.5 (2005)+ 1
(2008). Deepest extragalactic INTEGRAL survey
• Field: XMM-LSS (largest XMM field)• Flux limit: ~4x10-12 ergs cm-2 s-1 (20-40 keV)• Area: ~1,000 deg2
• Sources: ~20• Obscured AGN: ~15 (~5 Compton-thick)
INTEGRAL Mosaic (2.2 Ms)INTEGRAL Mosaic (2.2 Ms)
Significance Image, 20-50 keVSignificance Image, 20-50 keV
MCG-02-08-014MCG-02-08-014
MCG-02-08-014MCG-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 candidateGood CT AGN candidate
INTEGRAL AGN logN-logSINTEGRAL AGN logN-logS
Treister et al, submitted
Data points from Beckmann et al. 2006
Space Density of CT AGNSpace Density of CT AGN
Treister et al, submitted
X-ray background does not constrain density of CT AGN
CT AGN and the XRBCT AGN and the XRB
Treister et al, submitted
XRB Intensity
HEAO-1 +40%
Treister & Urry, 2005
CT AGN and the XRBCT AGN and the XRB
Treister et al, submitted
XRB IntensityHEAO-1 OriginalHEAO-1 +10%HEAO-1 +40%
Treister & Urry, 2005
Gilli et al. 2007
CT AGN and the XRBCT AGN and the XRB
Treister et al, submitted
XRB IntensityHEAO-1 OriginalHEAO-1 +10%HEAO-1 +40%
Treister & Urry, 2005
CT AGN Space Density
Most likely solution
Gilli et al. 2007
Treister & Urry 2005
X-ray Background X-ray Background SynthesisSynthesis
X-ray Background X-ray Background SynthesisSynthesis
Treister & Urry 2005
SummarySummaryAGN unification can account well for the observed
properties of the X-ray 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.AGN are luminous infrared sources, but contribute ~5%
to extragalactic infrared backgroundSurvey at high energies starts to constrain the spatial
density of CT AGN.