Transcript Slide 1
Evolution of Supermassive
Black Holes from deep &
large area X-ray surveys
Marcella Brusa
(Max Planck Institut fuer
Extraterrestrische Physik)
Outline
Introduction: AGN evolution
What we know: observations & models
Still missing (among others..):
high-redshift population
Compton Thick AGN census
Summary & future
AGN 8 - Torino, May 2008
Main actors in this game
XMM/Chandra COSMOS teams
CDFS/GOODS/MUSIC team
ELAIS-S1 team
HELLAS2XMM team
.. and in particular thanks to:
A.Comastri, F.Fiore, R.Gilli, A.Bongiorno, N.Cappelluti,
F.Civano, G.Hasinger, K. Iwasawa, V. Mainieri, A.
Merloni, M. Mignoli, S.Puccetti, M.Salvato, C. Vignali,
G.Zamorani, C.Feruglio, A.Grazian, F.LaFranca, F.Pozzi,
P.Santini…
AGN 8 - Torino, May 2008
introduction AGN evolution
Once upon a time… (1960s-70s):
QSO/AGN are triggered by accretion on SMBH
QSO/AGN are 1% of galaxy population:
transient phase or rare objects?
[45 years of observations]
Nowadays:
SMBH can be revealed in almost 100% of local
galaxies
AGN transient phase!
AGN 8 - Torino, May 2008
Co-evolution of galaxies and SMBH
MAIN OBSERVATIONAL RESULT: The discovery of dead SMBH in
most local bulges & tight correlation between MBH and bulge properties
Ferrarese & Merritt 2000
Gebhardt et al. 2000
Marconi & Hunt 2003
Marconi &
Hunt 2003
Large scale Galaxy properties strongly depend on BH mass
AGN 8 - Torino, May 2008
AGN and galaxy co-evolution
Early on
Strong galaxy interactions;
Mergers between gas rich
galaxies drive gas which fuel
both SF and BH activity;
Violent starbursts episodes;
Heavily obscured
BH this
growth
To prove
scenario
Li et al. 2007
we need:
When galaxies
1) Complete SMBH census,
coalesce
Accretion2)
peaks;
Physical models for AGN feedbacks
SMBH becomes optically
3) Observational
constraints to these models
“visible” (QSO
phase) as
AGN winds blow out gas
Later times
SF & BH accretion quenched;
Dead quasars (or slowly
accreting BH) in red
galaxies (passive evolution)
[see also Granato+2004, Di Matteo,
Springel & Hernquist 05, Hopkins+07]
AGN 8 - Torino, May 2008
How to study AGN evolution?
Count and detect AGN at different phase/stages of
their evolution
Surveys
Accretion Luminosity is emitted over a broad range of
wavelengths, BUT the X-ray emission is the AGN
footprint
X-ray surveys
AGN come in 2 flavours: unobscured and
obscured,obscuration affects mostly the soft X-ray
and optical wavelengths
Hard (>2 keV) X-ray surveys (unbiased)
Multiwavelength follow-up (redshifts!)
AGN 8 - Torino, May 2008
Evolution of Obscured AGN – why
bother? (1) XRB fit
Gilli, Comastri, Hasinger 07
Red -> unobscured AGN
Blue + Black -> obscured AGN
Obscured AGN
are needed to
reproduce the XRB
peak
[e.g. Setti & Woltjer 1989
…….
Gilli, Comastri & Hasinger 2007]
AGN 8 - Torino, May 2008
Evolution of Obscured AGN – why
bother? (2) BH growth
(Soltan 1982)
Soltan’s argument:
mass accreted is equal to the energy
released (E = mc2…)
IF all galaxies undergo an AGN phase
and
IF dead SMBH observed today are the remnants/witnesses of this phase
The BH mass density obtained integrating the luminosity emitted by
AGN over the cosmic time is expected to be similar to that measured
in local bulges
ρ(direct) ~ ρ ● ~ 3-5.5 x 105 M⊙ Mpc-3
INCLUDING ALSO
OBSCURED / CT AGN
AGN 8 - Torino, May 2008
[see e.g. Shankar et al. 2008
Marconi et al. 2004, Fabian 2003,
Fabian & Iwasawa 1999 etc]
Survey of surveys - X-rays + multiwave
CDFN-CDFS 0.1deg2
Barger et al. 2003; Szokoly et al. 2004
Flux 2-10 keV (cgs)
-16
E-CDFS 0.3deg2
Lehmer et al. 2005
C-COSMOS 0.9 deg2
Lockman Hole 0.2 deg2
Brunner et al. 2008
EGS/AEGIS 0.5deg2
Nandra et al. 2006
Contiguous
-15
-14
XMM-COSMOS 2 deg2
ELAIS-S1 0.5deg2
Puccetti et al. 06, Feruglio et al. 08
SEXSI 2 deg2
Eckart et al. 2006
HELLAS2XMM 1.4 deg2
Fiore et al. 20003
Cocchia et al. 2006
Champ 1.5deg2
Silverman et al. 2005
-13
(see Brandt & Hasinger 2005 ARA&A 43, 827)
XMM HBS ~25 deg2
Della Ceca+04,08
XBOOTES 9 deg2
Murray et al. 2005,
Brand et al. 2005
AGN 8 - Torino, May 2008
Area
Evolution
Hasinger+05
Fiore +03
La Franca +05
Bongiorno+07
picture quite clear from optical/soft/hard X-ray surveys:
Luminosity-Dependent Density Evolution (LDDE)
[see also Ueda+03, Cirasuolo+05, Della Ceca+08]
Anti-hierarchical growth/Downsizing
[Cowie et al. 1996, Merloni 2004, De Lucia et al. 2006]
AGN 8 - Torino, May 2008
Fraction of absorbed sources:
Luminosity dependence
Black: X-ray
Hasinger 2008
Hasinger et al. 2005
(see also
La Franca +05, Treister+05, Della Ceca+08)
Green: IR
Maiolino et al. 2007
Red: Optical
Simpson et al. 2005
fraction of obscured AGN is a strong function of L: most luminous,
less obscured
Same result in DIFFERENT bands despite the very different
selections!!
AGN 8 - Torino, May 2008
Fraction of absorbed sources:
Redshift dependence
La Franca +05
more debated!
Hasinger 2008
Seen in (some) data [e.g. La Franca+05, Treister+06, Hasinger08],
not seen in others (Ueda+03, Dwelly&Page 2006), not needed in XRB
models (Gilli+07) but expected/predicted in feedback models
(Menci+08)
AGN 8 - Torino, May 2008
Still missing (open problems)
Compton Thick objects / census
number density and evolution of high-z
population (z>3)
Interplay between AGN and SF / feedback models
[see Marulli/Fontanot]
Bolometric output/reprocessing [see Severgnini/Bellocchi/Lusso]
BH mass / accretion rate evolution [see Labita]
Elusive AGN (e.g. XBONGs/EXOs) [see Civano/Del Moro/Lanzuisi]
Role of the envinronment in triggering nuclear activity
[e.g. results from AEGIS/Groth strip – Georgakakis+07,08]
AGN 8 - Torino, May 2008
The population of z>3 QSOs
(XMM-COSMOS)
Brusa, Comastri, Gilli et al. 2008, ApJ, submitted
AGN 8 - Torino, May 2008
The population of z>3 QSO
Radio QSO
(Wall et al., 2005)
Optical QSOs
(Schmidt et al., 1995, Fan et al.
2001,2004)
COSMOS
?
X-ray: What happens at z>3?
decline or ~costant ?
Soft X-ray ROSAT/Chandra/ XMM
(Hasinger, Miyaji & Schmidt 2005)
Chandra/ROSAT
(Silverman et al. 2005/2007)
AGN 8 - Torino, May 2008
statistics still low at z~3-5
(NO statistics at z>6)
Cosmos
Survey
2 deg2 (PI: N. Scoville)
>150 team members
worldwide!
COSMOS major components (in order
of appearance) :
XMM-Newton
PI: G. Hasinger
HST/ACS (I-band – 590 orbits – I(AB)~27)
2002-2003:
Subaru imaging (~25 nights - b,v,r,i,z=26/27)
VLA (265 hours – 24 μJy)
GALEX deep (200 ks, AB~25)
XMM-Newton (800 ks – 10-15 cgs)
2004-2005:
XMM-Newton (600 ks)
VLT (540 hours) & Magellan (12+ nights)
SPITZER-IRAC (200 hours - ~1 μJy)
2006:
SPITZER-MIPS (200 hours - ~70 μJy)
Chandra (1.8 Ms)
http://cosmos.astro.caltech.edu
+ MAMBO,
ApJS special issue vol. 172 (>550
pages!) CFHT, Bolocam and (future) others
http://www.astro.caltech.edu/cosmos/
AGN 8 - Torino, May 2008
soft 0.5-2.0 keV
medium 2.0-4.5 keV
hard 4.5-10.0 keV
Hasinger et al. 2007
AGN redshift distribution in
XMM-COSMOS
X-ray sample (AGN)
Empty: specz+photz
Filled: specz
Sources extracted from a flux
limited sample in XMM-COSMOS
(50% of the area coverage in at least
one band)
1651 XMM sources
- 10% problematic ID using
IR+Chandra info
~670 “secure” spectroscopic
redshifts (40%), incompleteness
especially for high-z and Type 2
AGN
Accurate photometric redshifts
available (Salvato et al. 2008)
AGN 8 - Torino, May 2008
AGN photometric redshifts
434 objects with
“super-secure”
spectro-z (further
refinement/analysis)
Photo-z computed using
>30 bands:
SDSS, Subaru including
IB, CFHT, J, K, IRAC..
LESS than 10%
catastrophic outliers
(to be compared with
COMBO-17, Wolf et al. 2004)
AGN 8 - Torino, May 2008
Salvato et al. (in prep)
AGN redshift distribution in
XMM-COSMOS
X-ray sample (AGN)
Empty: specz+photz
Filled: specz
z>3 sample: 40
Sources extracted from a flux
limited sample in XMM-COSMOS
(50% of the area coverage in at least
one band)
1651 XMM sources
- 10% problematic ID using
IR+Chandra info
~670 “secure” spectroscopic
redshifts (40%), incompleteness
especially for high-z and Type 2
AGN
Accurate photometric redshifts
available (Salvato et al. 2008)
objects (22 specz + 18 photoz)
Additional 14 objects, no photoz available. Candidates very high-z AGN (EXOs,
Koekemoer et al. 2004)
AGN 8 - Torino, May 2008
Examples of images, spectra & photoz
XID 54439
z=4.241
B
g
v
r
I
AGN 8 - Torino, May 2008
z
IRAC 3.6
X-ray properties
HR vs.
redshift
Ratio of obscured/
unobscured objects
in agreement
with XRB models
AGN 8 - Torino, May 2008
Contribution to source counts
Lower bound: 22 spectro-z
Upper-bound: adding 10 EXOs
Dashed line:
Expectations from XRB models
using Hasinger et al. 2005 LF
Solid line:
Exponential decay introduced at
z=2.7 (Schmidt+95)
Flat evolution completely
ruled out
Tightest constraints to date
(largest and cleanest sample)
z>4 point:
Models: Gilli, Comastri & Hasinger 2007, A&A
AGN 8 - Torino, May 2008
Rhook & Haenelt 08 predict a factor
of ~3 higher wrt data
Space densities
Red curve:
predictions from XRB models
logLx>44.2 AGN (unobs+obs)
[Gilli+07 using Hasinger+05
and La Franca+05]
Dashed area:
(rescaled) space density for
optically selected bright QSO
[Richards+2006, Fan+2001]
Blue curve:
Silverman+08 LF, I<24 sample
AGN 8 - Torino, May 2008
The census of z~1-3 CT AGN/QSOs
(CDFS+COSMOS)
Fiore et al. 2008a, ApJ, 672, 94
Fiore, Puccetti, Brusa et al. 2008b, ApJ, submitted
AGN 8 - Torino, May 2008
Unveiling obscured accretion
X-ray surveys:
miss most highly obscured (Compton Thick) AGN
[e.g. Comastri 2004, Worsley et al. 2005]
IR surveys:
highly obscured AGN shine in the MIR – dust reprocessing
[e.g. Martinez-Sansigre et al. 2005, Polletta et al. 2006]
Goal:
combining X-ray and IR surveys to get the SMBH census and
compile AGN bolometric LF
X-ray-MIR surveys:
CDFS/GOODS/MUSIC [Grazian et al. 2006, Brusa et al. in prep, CDFS team papers]
ELAIS-S1/SWIRE [Feruglio et al. 2008, La Franca et al. 2008]
COSMOS [XMM-COSMOS: Brusa et al. 2008; + C-COSMOS/S-COSMOS papers]
AGN 8 - Torino, May 2008
MIR selection of CT AGN
All sources
BL AGN
NOT BL AGN
High MIR/O
Select candidate,
luminous obscured AGN
by imposing:
24 micron bright fluxes
(luminous) +
optically faint red sources
(optically obscured)
high MIR/O ratio
XMM-COSMOS sample
HR distribution [Brusa et al. 2008b]
See also results from ELAIS-S1, Feruglio et al. 2008, Lanzuisi’s talk
AGN 8 - Torino, May 2008
Combining MIR/O and R-K criteria:
selection of CT AGN at z~2
GOODS CDFS field
(1 Ms Chandra data)
+
MUSIC MW catalog
(Spitzer+HST+VLT)
~110 obscured AGN
candidates
Tracks of obscured AGN
Stack of Chandra
images excluding X-ray
detections in two
different MIR/O and
R-K bins
[Pozzi et al 2007]
Fiore et al. 2008a
See also Daddi et al. 2007
AGN 8 - Torino, May 2008
A new population of CT AGN
Daddi et al. 2007
Fiore et al. 2008
Martinez-Sansigre et al. 2005
Polletta et al. 2006
Low R-K or
The observed MIR luminosity
and the observed HR imply
(unobs) Lx>43 and NH>24 for
~80% of the sources
Curves: model predictions from
Gilli, Comastri & Hasinger
(2007) for L> 42, 43, 44, 45
AGN 8 - Torino, May 2008
COSMOS MIR AGN
Fiore et al. 2008b
High AGN fraction (~65%) in MIPS selected samples
(deeper X-ray data + more comprehensive analysis)
AGN 8 - Torino, May 2008
Summary
The fraction of obscured sources depend
strongly on luminosity
The fraction of obscured sources evolves
(increases) with redshift
Flat evolution at z>3 definitively ruled out
(space densities & number counts)
Significant population of CT QSO at z~2
detected
AGN 8 - Torino, May 2008
What’s next?
Compton Thick AGN/quasars:
XMM ultra deep 1.3 Ms (this fall)
exploit stacking… (Chandra 2 Ms)
Simbol-X (high-energy)
Herschel (reprocessing)
High-z quasars:
eROSITA (high-L)
XEUS (low-L and very high-redshift)
joint multiwavelength campaigns
AGN 8 - Torino, May 2008