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X-ray view of the most obscured QSOs at high redshift Chiara Feruglio CNRS - CEA, Saclay IRAM - Institut de RadioAstronomie Millim etr ique  thanks to: Daddi, Fiore, Piconcelli, Alexander, Malacaria, Puccetti et al. IXO science meeting, Roma, 14 March 2011.

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X-ray view of the most obscured QSOs

at high redshift

Chiara Feruglio

CNRS - CEA, Saclay

IRAM - Institut de RadioAstronomie Millimetrique 

thanks to:

Daddi, Fiore, Piconcelli, Alexander, Malacaria, Puccetti et al.

IXO science meeting, Roma, 14 March 2011


Why highly obscured, Compton thick, high luminosity AGN are so important:

  • They can be witnesses of a crucial phase in the AGN/galaxy coevolutionary sequence, an evolutionary scenario led by galaxy interactions (& mergers):

  • Obscured, rapid growth of both central SMBH and galaxy (high SF)

  • Onset of AGN feedback, through powerful winds

major mergers

galaxy-galaxy interactions

  • AGN power heats and expells the ISM in the disk, quenching star-formation [Silk & Rees 98, Di Matteo+ 05, Croton+ 06, King 05 Hopkins +08, Somerville+ 08, Menci +08, Catteneo+08]

The phase of highly obscured, intrinsecally luminous QSO

hosted in powerful SF galaxies

should be the best to catch AGN feedback


A spectacular example: QSO feedback in Mrk 231 so important:

The nearest (z=0.042, 187Mpc) QSO

  • Lbol=2 1046 erg/s

  • highly obscured, NH~1024 cm-2

  • loBAL with winds arising from the BLR

  • expanding bubbles on kpc scales seen by HST

  • hosted in a ULIRG with SFR ~200 MSun/yr

    (late stage merging system)

Braito+2004

Lipari+09

Goal : detect the outflow of the cold molecular

gas in the QSO host


QSO feedback revealed in Mrk 231 so important:

(Feruglio et al. 2010)

IRAM-PdBI detection of broad CO(1-0)

CO(1-0)

Broad

CO(1-0)

CO(1-0) @115.2712 GHz

Narrow component +

low surface brightness broad component with wings extending out to +-800 km/s

(FWZI = 1500 km/s).

OUTFLOW RATE

dM(H2)/dt = 700 M ⊙ /yr

Wings are spatially resolved and extended on 1.2 kpc scales.

SFR ~ 200M⊙ /yr

Kinetic energy of outflowing gas: E =1.2 1044 erg/s =

~1% LBol (2 1046 erg/s)

Map of Blue wing

Map of Red wing

expected for AGN radiation driven shock-wave

expanding in the ISM (Lapi+05)


Mrk 231 massive, Kpc-scale molecular outflow so important:

Confirmed by Herschel...

(Fischer et al. 2010)

The P-Cygni profiles of the OH 119 μm and 18OH 120 μm OH 79 μm blue-shifted lines

confirm the OUTFLOW with vel ~1400 km/s.

... and recently confirmed

by IFU spectroscopy (Rupke+2011)

Neutral gas absorption traces 2-3 Kpc scale

outflow with v ~ 1100 km/s powered by the AGN

Are SMBH/galaxy rapid obscured

growth and QSO feedback

common at z~2 ?

peak of AGN & SF activity


Gilli et al. 2007 so important:

Finding the most obscured, missing BH at high z

  • Finding highly obscured & Compton thick AGNs is extremely challenging because of

  • Obscuring column NH > 1024 cm-2

  • but crucial for:

  • the hard X-ray background

  • feedback on SF

  • BH mass-bulge relation

  • Recent discovery of very large gas reservoirs in high-z massive galaxies support rise in average NH (hence, in very obscured system) (Daddi et al. 2009, Tacconi et al. 2010)

Highly obscured

AGN


Finding the most obscured, missing BH so important:

  • IR selection of candidate highly obscured AGN, missed by hard X-ray surveys:

  • objects with mid-IR excess (Daddi+07)

  • obj bright in the mid-IR and faint in the optical (DOGs, Fiore+08,09, Martinez-Sansigre 2005)

  • Power-law SED in the IR (Lacy+2004, Polletta+2006, Donley+2008)

    X-ray stacking shows that a large fraction hosts highly obscured AGN.

    However, only X-ray observations can confirm the AGN nature of these sources, by estimating obscuration and the intrinsic AGN power.

mid-IR excess

DOGs

power-law SED


Compton thick AGN in the local universe so important:

Circinus galaxy

Only few dozen objects known even locally

Fe Kwith high EW (>1 keV)

on flat continuum

is the hallmark of

Compton thick obscuration

NH > 1.5 1024 cm-2

Guainazzi+2005

Fukazawa+2010


Gilli+2011 @z = 4.76 so important:

stacked

Compton thick AGN in the distant universe

a type 2 QSO at z=3.71

in CDFS (Norman et al. 02; 2)

Confirmed recently by

Comastri et al. 2011

(XMM survey of CDFS, 3 Ms)

Deep X-ray observations confirm a few CThick at high z with

  • Fe K 6.4 keV with EW > 1 keV

  • flat spectrum

Georgantopoulos+09, 6 CThick in CDFN, Fe K


Discovery of CThick QSO in two BzK galaxies at z~2.5-3 so important:

Feruglio, Daddi, Fiore, Alexander, Piconcelli & Malacaria, 2011

Based on the 4 Msec Chandra data of CDFS

BzK4892 zspec=2.578 Fe Kα (6.4 keV) > 4σ detection

EW=2.3 -0.6+1 keV

zspec=2.578

EW(Fe Kα) = 2.3 keV ==> COMPTON THICK QSO , NH>>1024 cm-2

L(2-10 keV) ~1044.5 erg/s, most likely 1045 erg/s

derived from Fe Kα, mid-IR , optical lines


Discovery of CThick QSO in two BzK galaxies at z~2.5-3 so important:

Feruglio, Daddi, Fiore, Alexander, Piconcelli & Malacaria, 2011

BzK8608 zphot=2.9

Fe Kα 3σ detection with EW=1.2 ± 0.4 keV

zphot=2.9

Compton-thick QSO, NH> a few 1024

Lx ~ 1044 erg/s


spectro-z so important:

Fe K redshift constraint vs optical redshift constraint

photo-z

  • FeK might be a useful tool (for future missions)

  • to measure redshifts of the most obscured systems

  • z/1+z ~ 0.02 (1)


The SF host galaxies of Compton thick QSOs so important:

Highly obscured QSO hosted in highly star forming, dust obscured galaxies

ACS

ACS

  • Mid-IR excess (x6),

  • U-band drop-out

  • SFR ~70 MSun/yr from UV

  • SFR ~300 MSun/yr from Radio

  • no Herschel detection

  • Extreme mid-IR excess (x170),

  • DOG, F(24um) = 591 uJy

  • U-band drop-out

  • SFR ~70 MSun/yr from UV

  • SFR ~1100 MSun/yr from Radio (VLA)

    SFR ~500 MSun/yr from Apex-Laboca 870 um

  • detected by Herschel PACS+Spire

  • ACS morphology suggests merger, 2 blobs


ERS+GOODS-MUSIC survey in the CDFS 4Msec exposure so important:

Compton thick AGN at z > 3

20-40keV

ERS (FF+11) GCH 2007

Treister 2009

2-10 keV Chandra/XMM

Large fraction of highly obscured AGN at z > 3 (3/17)

in CDFS 4Ms ERS survey (Fiore+2011).

Fraction of CThick~17% at F(2-10)~0.3-3 10-16 cgs

This is already ~ total CT fraction predicted by GCH2007. Fraction of CT at high-z may be higher than predicted before (similar result obtained by Gilli+ 2011)

E537 L(2-0keV)=1043.8 erg/s

E1577 L(2-10keV)=1043.6 erg/s

E8579 L(2-10keV)=1043.5 erg/s

Fiore+2011


ERS+GOODS-MUSIC survey in the CDFS 4Msec exposure so important:

Gas-to-dust ratio of the absorbing matter ~ 1/100-1/1000 of the Galactic value. Compact absorber <1 pc smaller than dust sublimation radius (see eg. Shi+2006) or smaller dust content

Filled:Point-like

Open: extended

Shi+2006

1/100

1/1000


Density of cthick agn
Density of CThick AGN so important:

  • @z=1.4-3 and L(2-10keV) > 1044 erg/s: 3E-6 Mpc-3 ~1 in 80 arcmin2

  • @z >3 and L(2-10keV) > 10 43.5 : ~ 1 in 25 arcmin2

  • In WFI 18x18 arcmin FOV it means between 2-10 obj. per field

NGC1068 Matt+2004

Simulated 100 and 500ks IXO/WFI spectra of ERS 537 and ERS 1577, assuming Fe Ka 6.4 keV, Fe He-like 6.7 keV and Fe H-like 6.9 keV as in NGC1068


The IXO view of CThick QSOs so important:

  • Simulated spectra of BzK4892 at z=2.578:

  • WFI in 100 ks make redshift of BzK-like objects z / 1+z ~ 0.01 (1

  • - XMS: detects emission lines only: search for sharp concentration of photons in deep XMS fields

A survey of 20 50/200ks fields would yield ~40 CThick with L(2-10keV) > 1044 erg/s at z<3 and ~160 with L(2-10keV)>1043.5 erg/s with spectra of quality similar or better to that available today with Chandra multiMsec exposures.

Surprises from search of photon concentration in energy in deep XMS pointings


Conclusions so important:

  • Luminous CT AGN can be witnesses of crucial phase in AGN/galaxy co-evolution: onset of AGN feedback

  • Chandra provides today the best evidence for luminous CThick AGNs at high-z

  • Tip of the iceberg: Lx ~ 1044 erg/s for BzK4892 Strong Fe Ka (30 counts in the line, 80 total in 4Msec)

  • Lx>1043.5 erg/s CThick AGN and/or higher z are fainter but still feasible with Chandra (Gilli+2011, Fiore+2011). They are probably more common, 1-2 per WFI FOV.


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