Transcript Document

AGN demography and evolution
Fabio La Franca
Dipartimento di Fisica
Universita` degli Studi ROMA TRE
Schmidt & Green 1983: i primi passi
~200 AGN1
20 years after…and two order of magnitude larger samples
Schmidt & Green 1983
Croom+04, 2dF QSO Redshift Survey
~24000 AGN1
~200 AGN1
Parameterization
SIMPLE POINTS:
• There is no
difference in PDE vs.
PLE for power-law
LF;
• But LF will
eventually turn over
for the total number
to converge;
• The real LF is likely
more complex
Parameterization
●
Quasar LF: double power-law

(L) 
(L /L* )  h  (L /L* )  l
*
'*

 (M) 
0.4[M M * ][  h 1]
0.4[M M * ][ l 1]
10
 10

Schmidt & Green 83, ~200 AGN1
20 years of evolution of the evolution
of the QSO (AGN1) luminosity
function
Boyle, Shanks & Peterson 88, ~700 AGN1
LF & Cristiani 97
~ 1200 AGN1
Croom+04
~24000 AGN1
L(z)=L(0)e6.15
PLE: L(z)=L(0)(1+z)3.4
What’s the Faint End Slope of QLF?
z=0
Faint slope measurement
Ranges from -1.o to -2.0…
lead to large uncertainties in
in the total luminosity and
mass density of quasar pop.
Hao et al. 2004
NLR H and [OIII] LF
High redshift QSO (AGN1) density
optical (grism) selection
Fan+04
SDSS
Schmidt, Schneider & Gunn 1995
See also Fontanot+07
High redshift QSO (AGN1) density
radio selection
Miller, Peacock & Mead 90
Dunlop & Peacock 90
Often rapidly varying:
small emission region
Broad spectral energy distribution
High-excitation emission
Non-stellar emission produced at the core of a galaxy (not always
visible at optical wavelengths)
●
–Broad wavelength SED: bright from X-rays (even gamma rays) to radio
wavelengths, unlike stars
–High-excitation emission lines not found in star-forming galaxies
–Sometimes highly variable, indicating very compact emission region
Before XMM and Chandra:
the X-ray LF from ROSAT
(Miyaji, Hasinger, Schmidt 2000)
0.5-2keV --> mainly AGN1
Previous works from Einstein data:
e.g. Della Ceca+92
X-ray background
the need for the AGN2/absorbed population
X-ray background
the need for the AGN2/absorbed population
Comastri, Setti, Zamorani, Hasinger 1995
AGN2-thin
AGN1
AGN2-thick
Some other CXRB synthesis models: Matt & Fabian (94); Madau, Ghisellini & Fabian (94);
Gilli+99; Pompilio, LF & Matt (1996); Treister & Urry (05); Gilli, Comastri & Hasinger (07)
X-ray Evidence for Absorption
●
X-ray observations show Type 2 AGNs have
larger column densities of gas than Type 1
AGNs (they are more absorbed)
Type 1 AGN
Type 2 AGN
There is rough correspondence
between optical AGN1/AGN2 classification
and column densities
First Spectroscopic identification of Chandra sources
XBONG
(X-ray Bright Optically Normal Galaxy)
Fiore, LF, Vignali et al. (2000)
The Lx-z plane and the modeld
LF, Fiore, Comastri+05
The fitting method
The number of observed AGN in the LX-z space is compared with
the number of expected AGN taking into account: 1) a
spectroscopic completeness correction, and 2) and an NH
distribution and corresponding X-ray absorption effects.
spectroscopic completeness correction
X-ray absorption dependent sky-coverage
NH column density distribution
Luminosity Dependent Density Evolution (LDDE)
(see previous results from
Ueda et al. 2003)
Lower luminosity AGN
peak at lower redshifts:
DOWNSIZING
(see models of galaxy and
AGN formations)
LF, Fiore, Comastri+05
Marconi+04
X-ray AGN LF
Brusa+09
0.5-2 keV: Hasinger, Miyaji, Schmidt 05
Downsizing of AGN activity
–
Quasar density peaks at z~2-3
–
AGN density peaks at z~0.5 - 1
●
Most of BH accretion happens in quasars at high-z
●
Most of X-ray background in Seyfert 2s at low-z
See also:
-Ueda+03 (selection effects included)
-Barger+05
-Silverman+08
-Della Ceca+08
-Ebrero+09 (selection effects
included)
-Yencho+09
-Aird+10
LDDE found also for optically selected AGN1
once the faint end of the LF is probed
Bongiorno, Zamorani+08
See also e.g. Fontanot+07, Shankar & Mathur 07
Downsizing in all bands
Hopkins, Richards & Hernquist (2007)
Bongiorno+10 find LDDE also for the AGN2 [OIII] LF
General Evolutionary Trends
Hopkins, Richards & Hernquist (2007)
• And a calculator:
www.cfa.harvard.edu/~phopkins/Site/qlf.html
The fraction of absorbed AGN as function of LX and z
INCREASE WITH THE REDSHIFT
assumed *)
predicted
DECREASE WITH LUMINOSITY
*) Assuming no luminosity and redshift dependences
Earlier evidences of a decrease of the fraction of absorbed AGN with luminosity from Lawrence & Elvis (1982) and
Lawrence (1991). Confirmed by Ueda et al. (2003).
LF, Fiore, Comastri+05
The fraction of absorbed AGN as function of LX and z
- Type 2 fraction a strong function of luminosity
a) At high (quasar) luminosity: type 2 <20%; optical color selection is highly
complete since all are type 1s, and includes most of luminosity AGN
population emitted in the Universe
b) At low (Seyfert) luminosity: type 2 ~80%; optical color selection miss most
of the AGNs in the Universe in terms of number
The decrease of absorbed AGN with increasing luminosity
(possible explanations)
Model 1
The Receding Torus Model: the
opening angle
of the torus increases with
ionizing luminosity
(e.g. Simpson 1998;
Lawrence 1991;
Grimes et al. 2003)
Model 2
The gravitational effects of the BH/Bulge
on the molecular gas disk of galaxies
Lamastra, Perola & Matt (2006)
The fraction of absorbed AGN as function of LX and z
Best fit: assuming L and z dependence
z
L
We confirm the evidences of a decrease of the fraction of absorbed AGN with luminosity and
find for the first time an increase of absorbed AGN with redshift.
LF, Fiore, Comastri+05
The fraction of absorbed AGN as function of LX and z
1815 AGN with intrinsic LX>1042 erg/s
Lx~45
Lx~44
Z~2.5
Lx~43
Z~1.8
Z~1.2
Z~0.7
Z~0.3
Melini, Thesis RmTre, 2009
Confirmed by: Treister & Urry 06, Ballantyne 06, Hasinger+08, Della Ceca+08
See discussion on possible selection effects in Akylas+06
The very hard (14-195 keV) XLF
Tueller, Mushotzky+08 (SWIFT/BAT)
Tueller, Mushotzky+08 (SWIFT/BAT)
CT about 20%
See also: Beckmann+06 and Sazonov+07
using INTEGRAL (20-40 keV)
A sample of
~500 SWIFT/BAT
AGN are going to
be investigated
by the INAF/Brera
and
INAF/Palermo-IASF
groups
Highly obscured
Mildly Compton
thick
INTEGRAL survey
~ 100 AGN
Sazonov et al. 2006
The very hard (>20 keV) XLF
Malizia+09 (INTEGRAL/IBIS)
Taking into account the
selection effects the NH
distribution is fully
compatible with [OIII]
selected samples
(e.g. Risaliti+99)
Estimate a fraction
of CT AGN >25%
The fraction of absorbed AGN as a function of flux
and the synthesis of the CXRB
L & z dependence (LDDE)
LF, Fiore, Comastri+05
The studies of the local galaxy bulges allow to estimate the z=0
BH mass funtion
Both the z=0 BH mass function and the cosmic X-ray
background are the “fossil” integrated result of the
AGN evolution, i.e. of the total of accreted mass and
of the total energy released in the Universe via accretion
z=0 BH mass function
X-ray background
Integrated luminosity
history
Integrated history of
accretion
Marconi et al. (2004)
Putting things together: Soltan’s argument
●
Soltan’s argument: QSO luminosity function Y(L,t)
traces the accretion history of local remnant BHs
(Soltan 1982), if BH grows radiatively


0
MnM ( M , t 0)dM 

t0
0
dt 

0
local
(1   ) Lbol
dL
 ( L, t );
2
c
accreted
n ( M , t ) : local BH mass function,
M
0
 ( L, t ) : QSO luminosity function,
 : efficiency, M 
(1   ) Lbol
c
2
.
Total mass density accreted = total local BH mass density
Accretion history of the Universe
Luminosity density
Accretion rate density
Bolometric correction
(Marconi et al. 04)
Luminosity density evolution
ε=0.1, radiative efficiency
Mass density in BH
BH mass density evolution
Marconi et al. (2004): 4.6 (+1.9;-1.4) M๏ Mpc-3
McLure & Dunlop (2004): 2.8 (+/- 0.4) M๏ Mpc-3
The history of BH mass density accreted
during quasar phase
Yu and Tremaine 2002
QSO mean lifetime


 (M ) 

t0
L( M )

M
dL   ( L,t)dt
0
nM ( M ' , t0 )dM '
~(3-13)107 yr
●
The mean lifetime of QSOs is comparable to the Salpeter time
(the time for a BH accreting with the Eddington luminosity to efold in mass).
Expanding Soltan’s Argument
Fitting QLF with local BHMF
Evidences for missing SMBH
Gilli et al. 2007
While the CXB energy density provides
a statistical estimate of SMBH growth, the
lack, so far, of focusing instrument above
10 keV (where the CXB energy density
peaks), frustrates our effort to obtain a
comprehensive picture of the SMBH
evolutionary properties.
43-44
44-44.5
Marconi 2004-2007
Menci , Fiore et al.
2004, 2006, 2008
Completing the census of SMBH
●
●
X-ray surveys:
–
very efficient in selecting unobscured and
moderately obscured AGN
–
Highly obscured AGN recovered only in
ultra-deep exposures
IR surveys:
–
AGNs highly obscured at optical and X-ray
wavelengths shine in the MIR thanks to the
reprocessing of the nuclear radiation by dust
The MIR 15um LF from ISO
AGN1: L(z)=L(0)(1+z)2.9
AGN2: L(z)=L(0)(1+z)1.8-2.6
Matute, LF, Pozzi+06
IR surveys
Difficult to isolate AGN from star-forming galaxies
(Lacy+04, Barnby+05, Stern+05, Polletta+06, Gruppioni+08, Sacchi, LF, Feruglio+09 and many
others). See e.g. discussion of the wedge (Stern) selection in Gorgantopoulos+08 or the analysis by
Brusa+10
Georgantopulos+08
Stern+05 selection
Martinez-Sansigre+05
Sacchi, LF, Feruglio+09
Lacy+04 selection
MIR selection of AGN
Gruppioni+08
Gruppioni+08
SED library from Polletta+07
The problem is:
1) to separate the AGN from the galaxy SF contribution:
e.g. Polletta+08, Fritz+06, Pozzi+07+10, Vignali+09
2) Need to deeply observe in the X-ray band in order
to measure the column densities
MIR selection of CT AGN
Fiore+08
see also Daddi+07
Fiore+09
CDFS X-ray
HELLAS2XMM
GOODS 24um
galaxies
R-K
COSMOS
X-ray
COSMOS
24um
galaxies
Open symbols =
unobscured AGN
Filled symbols =
optically obscured
AGN
* = photo-z
MIR AGNs
Fiore+08+09
Stack of Chandra
images of MIR
sources not directly
detected in X-rays
See also Lanzuisi+09
F24um/FR>1000 R-K>4.5
logF(1.5-4keV) stacked
sources=-17 @z~2 logLobs(28keV) stacked sources ~41.8
log<LIR>~44.8 ==> logL(2-8keV)
unabs.~43
Difference implies logNH~24
Sacchi, LF+09 VLT observations
showed that about 70% of the
300<X/R<1000 DOGs have an
AGN optical spectrum
Sacchi, LF, Feruglio+09
Flux 0.5-10 keV (cgs)
CDFN-CDFS 0.1deg2
Barger et al. 2003; Szokoly et al. 2004
-16
-15
-14
E-CDFS 0.3deg2
Lehmer et al. 2005
EGS/AEGIS 0.5deg2
Nandra et al. 2006
C-COSMOS
0.9 deg2
ELAIS-S1 0.5 deg2
Puccetti et al. 2006
XMM-COSMOS
2 deg2
HELLAS2XMM
1.4 deg2
Cocchia et al. 2006
Champ 1.5deg2
Silverman et al. 2005
SEXSI 2 deg2
Eckart et al. 2006
-13
XBOOTES 9 deg2
Murray et al. 2005, Brand et
Pizza
Plot
Area
AGN host galaxies
Obscured (no AGN1) AGN in the
most massive and redder galaxies
A significant fraction of obscured
AGN live in massive, dusty star-forming
galaxies with red optical colors
AGN preferentially reside
in the red sequence and
in the “green valley”
(Nandra+07, Silverman+08,
Hickox+09)
Brusa+10
Z>3 AGN counts
Lower bound: 22 spectro-z
Upper-bound: adding 10 EXOs
Dashed line:
Expectations from XRB models
extrapolating Hasinger+05 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)
Models: Gilli, Comastri & Hasinger 2007, A&A
Space densities
Red curve:
predictions
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
Brusa+09
The radio LF and the sub-mJy radio counts
La Franca+05
=
X
L
1.4GHz/LX
La Franca+05 (& Brusa+09 at z>2.7) P(R| L , z) from LF, Melini
X
& Fiore, ApJ, subm
Brusa+09
The sub-mJy radio counts and the radio LF
LF, Melini & Fiore, ApJ, subm
SUMMARY
-AGN LF (in the optical, [OIII], X-soft, X-hard bands ) evolves accordingly to
the LDDE model (-->downsizing)
-X-ray obscuration increases with increasing redshift and decreasing
luminosity
-Integrating the AGN LF, the CXRB and the local BH mass
function are fairly well (roughly ?) reproduced
-MIR search for obscured AGN do not seem to find a new (huge)
population of X-ray obscured AGN which clearly show an
AGN like SED in the MIR.
-SWIFT and INTEGRAL have not found column densities significantly
different from expectations (taking into account selection effects)
-The radio AGN LF is in agreement with the XLF if the Radio/X distribution
is taken into account
-X-ray surveys are starting to probe the z>3 XLF which results in rough
agreement with the AGN1 evolution in the optical (and radio)