ulirg workshop cornell 2006 agn conference, xi‘an, 2006e. sturminfrared dust properties dust in...

ULIRG Workshop Cornell 2006

AGN Conference, Xi‘an, 2006 E. SturmInfrared Dust Properties

Dust in the Infrared – a prime tool for AGN diagnostics

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Eckhard Sturm

The QUEST Collaboration



Infrared dust spectra can help us to understand• AGN torus and NLR - physical properties • AGN unification • AGN host galaxies • AGN – Starburst connection• AGN evolution• ...

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The dust components of mid-infrared galaxy spectra

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Silicate

Ices

silicate

Pier & Krolik 92



I) The continuum

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Weedman et al. 2005

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Weedman et al. 2005

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Weedman et al. 2005

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Buchanan et al. 2006

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Also read: poster by Rajesh et al.-> talks by Hao, Ogle



The slope of the continuum

Weedman et al. 2005Sturm et al. 2000

Sturm et al. 2006, Rupke et al.

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IR-faint LINERs

IR-bright LINERs

Sturm et al. 2006Rupke et al., in prep.

Selection based on Ho et al. 1997, Satyapal et al 2003, Veilleux et al. 1995

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SDSS Simpson et al. 2005

Decreasing Type2 fraction with increasing luminosity?

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Lutz et al. 2004Sturm et al. 2006

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II) Silicates

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QUEST (Veilleux et al.)Schweitzer et al. 2006

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Silicate emission in Type 2 objects!

NGC 4725: Type 2 AGN from Ho sample (SINGS data, Kennicutt et al.)

QSO2s: Sturm et al. 2006

IRASF10214+4724: Teplitz et al. 2006

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Dust outside sublimation Radius: > ~0.5 L46

0.5pc

Silicate emitting dustRadius: ~200 L46

0.5pc

?AGN

Silicate emission – where from?

The simplest cartoon

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Dust outside sublimation Radius: > ~0.5 L46

0.5pc

Silicate emitting dustRadius: ~200 L46

0.5pc

?AGN


The simplest cartoon

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Similar Galactic SEDs: flared, passive irradiated protostellar disks

Dullemond et al. 2001, 2004

… but of course cannot be scaled simply!


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Shi et al. 2006


One alternative cartoon

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NGC 3998 (Liner 1.9), Sturm et al. 2005

Finding silicate around weaker AGN or, e.g., in ULIRGs is more difficult due to PAH “contamination”

Schweitzer et al. 2006

Silicate emission observed also at lower luminosity

Silicate emission – luminosity dependent?

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• Sizeable population of Type 1 AGN with silicate emission

• Incidence as a function of luminosity and other factors still under investigation

• Demonstrates presence of a significant component of optically thin silicate dust

Is this the “unified” silicate emission from the torus?

• Cold Temperatures ~140K-220K (from feature ratio and ISM silicate emissivity profile). Too cold for inner side of torus near sublimation but ok for dust further out, e.g. in the NLR? • emission also in Type II objects

Silicate emission – the Torus?

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Average QSO SED: three mid-infrared bumps

3m bump –1000-1500K Two silicate bumps

QUEST

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Intrinsic QSO SED

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Netzer et al. (in prep)



III) PAHs(Polycyclic Aromatic

Hydrocarbons)

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AGN Conference, Xi‘an, 2006 E. SturmInfrared Dust Properties 26/35



QUEST (Veilleux et al.)Schweitzer et al. 2006

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PAHs in Quasar host galaxies



Average spectra: PAH is widespread


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The origin of QSO far-infrared emission

Rowan-Robinson (1995) pure AGN SED – strong far-infrared then must be star formation

Sanders et al. 1989: warped disk couldprovide enough cold but AGN-heated dust

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The origin of the far-IR emission in QSOs (Starburst-AGN connection)


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• Widespread presence of PAH emission in z<0.3 PG QSOs indicating the presence of powerful starburst activity (νLν60 ~ 2x1010 … 2x1012 L_sun)

•Far-infrared emission in QSOs arises mostly from star formation

• The star formation environments in the QSO hosts are very similar to ULIRGs

• Star formation activity and AGN luminosity correlate up to high luminosity, and starbursts and AGN phase coexist

The origin of the far-IR emission in QSOs (Starburst-AGN connection)

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Selection based on Ho et al. 1997, Satyapal et al 2003, Veilleux et al. 1995

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IR-bright LINERs

Sturm et al. 2006Rupke et al., in prep.

IR-faint LINERs

PAHs in LINER host galaxies



Mid-Infrared diagnostics of LINERs

Sturm et al 2006, Rupke et al. (in prep.), SINGS (J.D. Smith et al., in prep.)

cp. Hony et al. 2001 (HII regions, YSOs, evolved stars)cp. Cesarsky et al. 1998, Pagani et al 1999 (star forming regions in M31)

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Same methods can now be applied at high redshifts

Yan et al. 2005, Houck et al. 2005, Lutz et al. 2005, Weedman et al. 2005b, Desai et al. 2006, Valiante et al. 2006, etc.

Appilication at high redshift

z~2.8 SMG from Lutz et al. 05

z~1.3 ULIRG from Desai et al. 06

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Continuum shape (flux ratios 15/6 and 30/6): tool to distinguish AGN types?Continuum ratio mid-IR/X-ray: unification, luminosity dependence of TypeII/TypeI?Silicates: unification (Torus and/or extended emission?)Silicates: luminosity dependence? Crystallization? Grain size distribution?PAHs in QSOs: host galaxy diagnosticPAHs in QSOs: origin of far-IR continuumPAHs in LINERs: tool to distinguish LINER types at high redshift?Continuum + silicates + PAHs: tool to analyse high redshift dusty galaxiesContinuum + silicates + PAHs: tool to study AGN evolution

Summary

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ulirg workshop cornell 2006 agn conference, xi‘an, 2006e. sturminfrared dust properties dust in...

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