may 19-22, 2014 bologna models for agn dust tori michael rowan-robinson imperial college london

May 19-22, 2014 Bologna

Models for AGN dust tori

Michael Rowan-Robinson

Imperial College London


Unified models for AGN: first ideas

first attempt at ‘unified model’ for quasars, Seyferts, radio-galaxies: Rowan-Robinson 1976 - Type 2 are obscured Type 1, link to 10 m emission ?

Miley et al 1984: IRAS detection of mid-ir excess from AGN.R-R & Crawford 1989: first model of this excess as dust torus around AGN

developed into unified model (Antonucci 1993, Krolik 1999) in which different AGN types are a function of the viewing angle

more detailed models: Pier and Krolik 1992, Granato and Danese 1994, Rowan-Robinson 1995, Efstathiou & R-R 1995, Bianchi et al 2012

today: X-ray AGN classified as: unobscured (lg N(H)<22), Compton thin (lg N(H) = 22-24), or Compton thick (lg N(H)>24)

- these should all be detectable as dust tori in the mid-ir- open question; could there be a major population of heavily obscured AGN,

not detected at 1-10 keV in X-rays (could help explain hard-X background)

May 19-22, 2014

Bologna

AGN dust torus geometry

Efstathiou & R-R 1995

AGN dust torus seds as function of viewing angle

tapered disk models

Efstathiou & R-R 1995


3-D radiative transfer models for clumpy AGN dust tori

- Rowan-Robinson 1995, slab model for clumpy torus in QSOs

- Nenkova et al 2002, 2008, 5-10 clump model for NGC1068 (slab model)

- Dullemond and van Bemmel 2005, Monte Carlo

- Shartmann et al 2005, 2008, Monte Carlo

- Honig et al 2006, Monte Carlo

R-R 95



Recent studies of AGN seds

• Franceschini et al 2005: seds of X-ray AGN in XMM MDS

• Polletta et al 2006, 2007: seds of X-ray AGN in Lockman

• Rowan-Robinson, Valtchanov & Nandra, 2009: comparison of X-ray (CLAS-X) and mid-ir (Spitzer-SWIRE) data

• Hatziminoglou et al 2010: Herschel observations of QSOs

• Hao et al 2010: weak dust tori in XMM-Cosmos

• Bianchi et al 2012: AGN obscuration and the unified model • Ruiz et al 2013: modelling 13 HLIRGs with IRS data – all have strong tori

• Lusso et al 2013: seds modeled for 32 QSOs with vel. shifts


Spectral energy distributions (SEDs) of a deep Lockman X-ray sample (Polletta et al 2006)

BlueRed

Red Blue Red Red

Soft

HardSoft

26% Type 1

19% Type 243% Normal

8% AGN/ULIRG

4% True normal

(see also Franceschini et al. 2005;Rigby et al. 2004, 2005; Alonso-Herrero et al. 2004;Alexander et al. 2001, 2002; Fadda et al. 2001)


X-ray detected Compton-thick AGN

•Selection criterion:•HR, z NH≥1024 cm-2

•5 sources (z=1.4-2.5)

•SEDs:•2 AGN (40%)•3 normal galaxies (60%)

(Polletta et al 2006)

other studies of Compton-thick AGN:

• Daddi et al 2007

• Fiore et al 2008,2009

• Alexander et al 2008

• Brightman et al 2012

X-ray Optical IR X-ray OpticalIR

νFν

νFν

νFν

Observed Wavelength

Observed Wavelength

Stars

AGN

Stars

Stars

AGN


• F(0.3-8 keV) = 2.7x10-15 erg cm-2 s-1 • HR = 0.85 NH= 2x1024 cm-2 & Lx= 1.2x1046 erg s-1

• Lbol = 4x1047 erg s-1 & MBH =3x109 M☉

• Optical: blue with narrow lines (z=2.54) scattered light (0.6%)

• IR: red (r’-K = 4.2) model as QSO with AV=4

The most luminous Compton-thick quasar, z=254Fν (μJy)

z=2.54(Keck/LRIS)

Fν (μJy)

dust torus model (Eftstathiou and RR 2003)


HerMES survey


combining surveys by Chandra and Spitzer

Rowan-Robinson, Valtchanov, and Nandra 2009, MNRAS


some statistics on Spitzer-SWIRE survey

• over 1.5 million galaxies in SWIRE survey

• 10% have z > 2, 4% have z > 3

• 20% detected at 24 m, 1% at 70 or 160 m

• 35% of 24 m sources are dust torus dominated at 8 m (9% of these are QSO1, most of rest Seyfert) • 5% of 24 m sources are hyperluminous (Lir > 1013)

• do find some reddened QSOs, but only 5% of QSO1 have Av > 0.5


SWIRE+X-rays

CLASX Chandra X-ray survey in Lockman (Yang et al 2004), 0.4 sq deg, 426 extragalactic X-ray sources, 322 detected bySWIRE, 162 of which areQSOs or have dust tori

a further 273 SWIRE sources are QSOs or have dust tori (total SWIRE population inCLASX area: 8563)

black dot: E, Sabred dot: spiral,sbblue dot: QSOgreen sq: dust torus

LX


24 m v. X-ray flux

Wide range of ratio of 24 m flux to X-ray flux(0.004-1.0 mJy/10-15 erg/cm2/s)(Rowan-Robinson, Valtchanov,

Nandra, 2009)

green triangle: broad line blue square: narrow line red square:galaxy spectr. magenta square: no spec z black circle: optical QSO crosses: upper limits filled circles- ir template type red: M82 starburst blue: AGN dust torus green: Arp 2200 starburst


Ltor/Lopt v. Ltor for SWIRE AGN dust tori

red: M82 sb dominated at 8 mblue: AGN dust torus

dominated


Ltor/Lopt v. Lor

use volume limited sample of tori to quantify covering factor f=L(tor)/L(opt-uv). Find <lg10 f> = -0.4, =0.26, I.e. f = 0.4.

[cf Roseboom et al (2013): <lg10 f> = -0.41, =0.2]


Hydrogen column-density v. X-ray luminosity

Use hard/soft X-ray flux ratio to estimate line-of- sight absorption, N(H)

Z>2.3

LXh is corrected for absorption


L(tor) v. L(Xh,c)

luminosity in dust torus versus X-ray luminosity

lines correspond to covering factor f = 0.01, 0.1, 1, 10 (can’t have > 1! So eitherX-ray bolometric correction underestimated, or there has been additional absorption in X-rays)

1 0.1


L(tor)/L(opt) v. L(opt)

lg {L(tor)/L(opt)} ~ lg f, versus lg L(opt), (Lsun) for all SWIRE AGN.

we see many low-luminosity tori with SWIRE which are not detected at X-rays



L(opt)/LX v. soft/hard

lg {L(opt)/LX} versus ratio of soft to hard X-ray flux for all SWIRE AGN.


excluding QSOs flagged as optically extended or withN(H) > 1023

define Lbh~27 LXh

~2 Lopt ~ 2.5 Ltor


L(tor)/L(opt) v. LX

lg {L(tor)/Lbh} ~ lg f, versus lg LX, (Lsun) for all SWIRE AGN.

objects above horizontal line are candidates for being Compton thick.



Summary on covering factor

RR et al 2009: covering factor decreases from high to moderate X-ray luminosity, then may increase towards lower luminosities

Hasinger (2008): ratio of narrow-line to broad-line AGN increases with decreasing hard X-ray luminosity

Maiolino et al (2007): Type 2 fraction increases as luminosity decreases (based on ratio of 6.7 m to 5100 A)

La Franca et al (2005), Hasinger (2008), Treister et al (2008): suggest fraction of obscured AGN increases with redshift


L(tor) v. z

lg {L(tor)} versus z for all SWIRE AGN.

wider dynamic range than the X-ray luminosity, more low-luminosity, low-z, dust tori

blue square: narrow line red square:galaxy spectr. black circle: optical QSO filled circles- ir template type red: M82 starburst blue: AGN dust torus green: Arp 2200 starburst


very strong (Compton thick ?) tori

Left: L(tor) > L(bh) - Compton thick candidates ? Right: lg N(H) > 24 (cm-2) - Compton thick


summary on Compton thick AGN

Polletta et al (2006) identifies 7 sources with N(H) > 1024 cm-2, estimated 55 in 0.6 sq deg, only 20% of which detected in X-rays.

R-R, Valtchanov, Nandra (2009) found 1 source with with N(H) > 1024 cm-2, with a further 11 candidates for which Ltor>Lbh.Estimated > 130 in 0.4 sq deg CLAS-X area, >20% of sample.

Fiore et al (2009) estimate 44% of X-ray sources with log Lx =44-45 and 67% with log Lx = 43.5-44 are Compton thick.

Alexander et al (2008) note paucity of reported Compton thick objects at z = 2-2.5. Discuss one new object + 6 in literature.


very weak tori ?

L(tor) < 0.03 L(bh) - very weak or no tori ?

All consistent with 1-3%covering factor.

No strong evidence for < 1% covering factor(Rowan-Robinson et al 2008)

see also: Jiang et al 2010 (two z~6 QSOs with no detectable hot dust), Hao et al 2010 (found substantial population of ‘hot-dust-poor’ AGN in XMM-Cosmos, ~10%)- torus destroyed during merger ?


starburst-AGN connection

Left: L(sb) (measures star-formation rate) v. L(Xh,c) [broken line - locus for X-ray starbursts].

Right: L(tor) v L(sb) - RR(2000), hyperluminous gals.(1) Strong correlation - link between AGN and star formation (2) these are differential versions of the Magorrian diagram (Mbh - M*)


X-ray starbursts

• 7-10 X-ray starbursts, LX up to 1044 erg/s

Rowan-Robinson, Valtchanov, Nandra, 2009

X-ray starbursts


Obscuration and unified model

Spectra of NGC 1365 showing

occultation by BLR clouds

Model of absorbing radiation for

right-hand event.

(Maiolino et al 2010)

Bianchi et al 2012



Left: Model for Circinnus galaxy (Tristram et al 2007).

Right: dusty torus derived from mid-ir interferometric observations



Geometry of circumnuclear matter in NGC 1068 (Raban et al 2009).

Red: compact dust from mid-ir interferometry.

Blue: ionization cones from OIII.

Yellow: ionization cones from spectroscopy.

may 19-22, 2014 bologna models for agn dust tori michael rowan-robinson imperial college london

Documents

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daddi et

fiore et

miley et

brightman et

seds of xray agn

unified model ruiz et

obscured agn