Luminous obscured quasars in the Luminous obscured quasars in the HELLAS2XMM survey: HELLAS2XMM survey: the the SpitzerSpitzer perspective perspective

Cristian VignaliCristian VignaliDipartimento di Astronomia, Dipartimento di Astronomia,

Universita`degli Studi di BolognaUniversita`degli Studi di Bologna

F. PozziF. Pozzi, A. Comastri, C. Gruppioni, , A. Comastri, C. Gruppioni,

L. Pozzetti, M. Mignoli, C. Lari, G. L. Pozzetti, M. Mignoli, C. Lari, G. Zamorani, M. Brusa Zamorani, M. Brusa

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The HELLAS2XMM collaborationThe HELLAS2XMM collaboration

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The culprit …The culprit …Who inspired this work …Who inspired this work …

Radio-quiet quasarsRadio-quiet quasars Radio-loud quasarsRadio-loud quasars

Elvis et al. 1994

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……and some recent results …and some recent results …

Richards et al. 2006

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Talk outlineTalk outline

The importance of obscured AGNobscured AGN: the X-ray view

Why SpitzerSpitzer?

Sample selection: luminous, obscured quasars in the luminous, obscured quasars in the HELLAS2XMMHELLAS2XMM survey and KS-band morphology of their hosts

A quick look at the Spitzer IRACIRAC and MIPS dataMIPS data

Broad-band spectral energy distributions spectral energy distributions using IRAC+MIPS24 data: first results

Physical properties of the X-ray selected obscured quasar population from HELLAS2XMM: bolometric corrections, BH masses, and bolometric corrections, BH masses, and Eddington ratiosEddington ratios

Mission impossible: all in 10 minutes! Mission impossible: all in 10 minutes!

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The importance of obscured AGN: The importance of obscured AGN: the X-ray viewthe X-ray view

A large fraction of the accretion-driven energy density in the Universe is obscured by dust and gas

(e.g., Fabian 1999)

Ingredient of the X-ray background synthesis models (e.g., Comastri et al. 1995; Gilli, Comastri & Hasinger 2007)

the high-luminosity, obscured AGN population (Type 2 Type 2 quasarsquasars), expected on the basis of Unification schemes, only partially found

Obscured phase of the AGN growth linked to the host galaxy formation?

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Why Spitzer?Why Spitzer?

The nuclear emission is re-processed in the IR band (by the dusty torus envisaged by the model?), less affected by extinction

Spitzer provides coverage over the 3.6-24 μm wavelength range (and also at 70 and 160 μm is some cases)

IR emission important to compute the resulting bolometric luminosity of obscured, luminous AGN through their SEDs

REQUIRED: removal of the galaxy contributionREQUIRED: removal of the galaxy contribution

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Sample selection: obscured quasarsSample selection: obscured quasarsfrom the HELLAS2XMM surveyfrom the HELLAS2XMM survey

•SAMPLE: HELLAS2XMM F2-10 keV >10-14 erg cm-2 s-1 over 1.4 deg2

•Optically faint (R>24) sources with no optical identificationhigh X-ray-to-optical flux ratio (X/O>10) sources with indications of X-ray obscuration

Mignoli et al. 2004Mignoli et al. 2004

• ALL bright in the KS band

• All have R-KS>5 Extremely Red Objects (EROs), some are extreme• Most have elliptical profiles, two are point-like (Mignoli et al. 2004)

ISAAC KISAAC KSS-band follow-up-band follow-up

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High X/O population unveiled also by High X/O population unveiled also by ChandraChandra

e.g., SEXSI survey: Eckart et al. 2006

Log (X/O)>1Log (X/O)>1≈≈10-20% of the sources 10-20% of the sources detected in the X-ray detected in the X-ray surveys have X/O>1surveys have X/O>1

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BLAGN

EROs

X/O>10 Lx=1044.7

z=1.2

Point-like + steep PL SED

Extended + galaxy-dominated SED (Civano et al., in prep.)

a significant fraction of EROs is associated with X/O>10 sourcesEROs have larger X/O than broad-line AGN

similarly, in the COSMOS survey…similarly, in the COSMOS survey…

Lx=1045

z=1.59

acs

acs

mips 24mips 24

mips 24mips 24

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What about the source redshifts?What about the source redshifts?

Estimated redshift range: 0.8<z<2.40.8<z<2.4 (from photometry, Mignoli et al. ’04) – 6/8 sources6/8 sources

2/8 sources: secure spectroscopic redshifts from ISAAC (Maiolino et al. ’06)

Maiolino et al. 2006Maiolino et al. 2006LINER (X/O=52)LINER (X/O=52) QSO 1.9 (X/O=78)QSO 1.9 (X/O=78)

NNHH~10~102323 cm cm-2 -2 + L + L2-10 keV2-10 keV>10>104444 erg/s erg/s Type 2 QSOsType 2 QSOs

J H KJ H KSS J H KJ H KSS

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KKSS-band images with 24 -band images with 24 μμm contoursm contours

40 arcsec

All sources detectedAll sources detected in IRAC & MIPS24

S(24 μm)=150-1000 μJy

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Spectral Energy Distribution: the Spectral Energy Distribution: the modeling (I)modeling (I)

Host galaxyHost galaxy Elliptical galaxy normalized

to Ks

+ Torus emissionTorus emission

Template from Silva et al. ’04

Bulge-dominated sources Bulge-dominated sources

LLbolbol=f(L=f(LXX; N; NHH))every source model normalized

using its X-ray luminosity and NH values

Silva et al. 2004

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Bulge-dominated sources (in KBulge-dominated sources (in KSS): ): nuclear vs. host-galaxy emissionnuclear vs. host-galaxy emission

NUCLEAR COMPONENT: NUCLEAR COMPONENT: not a SED fitting!not a SED fitting! normalized to X-ray observables: Lnormalized to X-ray observables: LXX and N and NHH

Elliptical galaxy + nuclear component

= match the data within a factor of 2-3

Nuclear comp.consistent with KS

upper limits

Nucleus starts dominating at ≈6 μm

from Pozzi et al., WORK IN PROGRESS

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Point-like sources Point-like sources (in the K(in the KSS band) band)

Extincted Type 1 quasarExtincted Type 1 quasar oror red quasar red quasar template template (from Polletta et al. 2006) normalized to 24 μm

Extincted Type1 quasar NOT able to reproduce the data sharp decrease in the optical

Good match using a red QSO template

Spectral Energy Distribution: the modeling (II)Spectral Energy Distribution: the modeling (II)

from Pozzi et al., WORK IN PROGRESS

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Bolometric correction and luminosityBolometric correction and luminosity

Bolometric luminosity = LBolometric luminosity = LBOLBOL = k = kXX L L2-10 2-10

keVkeV

LBOL

1. Sum the radiation directly linked to the Sum the radiation directly linked to the accretion accretion

LBOL= LX,INT + LOPT,UV

REQUIREDREQUIRED: : ►►to remove IR bump (re-processed radiation)to remove IR bump (re-processed radiation) ►to correct for gas/dust absorption in X-to correct for gas/dust absorption in X-

ray, optical, and UVray, optical, and UV

2. Integration of the observed luminositiesIntegration of the observed luminosities LBOL≈∫ observed SED = LX,OBS+ LIR,OBS

our approach

bolometric correction bolometric correction (≈35 in Type 1 QSOs from Elvis+ 94)(≈35 in Type 1 QSOs from Elvis+ 94)BUT large dispersion in the broad-line QSO SEDs BUT large dispersion in the broad-line QSO SEDs

16from Urry & Padovani 1995

Corrections applied to the obtained face values to account for

covering factor ↔ opening covering factor ↔ opening angle of the torus ↔ angle of the torus ↔ N(AGN2)/N(AGN1) in this LN(AGN2)/N(AGN1) in this LXX range range

from Gilli+ 07 XRB modelsfrom Gilli+ 07 XRB models factor 1.5 factor 1.5

anisotropy ↔ only part of the anisotropy ↔ only part of the re-emission from the torus re-emission from the torus reaches the observer reaches the observer ≈≈10% 10% according to Silva+ 2004 templates

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Median kMedian kXX = L = LBOLBOL/L/L2-10 keV2-10 keV ≈ 27 ≈ 27

Red QSO at z=2.08

Bolometric correction: preliminary Bolometric correction: preliminary resultsresults

bulge-dominatedbulge-dominated

point-likepoint-like

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Bulge and black hole massesBulge and black hole masses

KS-band flux mostly from the host galaxy LK MBH using the Marconi & Hunt (2003) local relation and assuming (MBH/M*)z=1 = 2(MBH/M*)z=0 (Peng+ 06)

Bulge-dominated sources Bulge-dominated sources

<M<MBHBH> > ≈≈ 10 1099 M M

Eddington ratio=LEddington ratio=LBOLBOL/L/LEDDEDD ≈ 0.06 ≈ 0.06

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BH masses: BH masses: comparison with SDSS comparison with SDSS quasarsquasars

Indications that: these luminous these luminous obscured QSOs, obscured QSOs, residing in Kresiding in KSS--luminous galaxies, luminous galaxies, have have massive black holes

SDSS data from McLure & Dunlop ’04SDSS data from McLure & Dunlop ’04

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Eddington ratios: Eddington ratios: comparison with SDSS comparison with SDSS QSOsQSOs

Indications that: these very massive, X-these very massive, X-ray luminous black holes ray luminous black holes at at zz≈1-2≈1-2 have have already passed their rapidly accreting phase

they have they have reached their final masses with low accretion rates

SDSS data from McLure & Dunlop ’04SDSS data from McLure & Dunlop ’04

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if you have questions…if you have questions…

I’m not sure I can answer …

THE ENDTHE END