Fabio La Franca
Dipartimento di Fisica
AGN demography and evolutionAGN demography and evolution
Universita` degli Studi ROMA TRE
Schmidt & Green 1983: i primi passi
~200 AGN1
Schmidt & Green 1983
~200 AGN1
Croom+04, 2dF QSO Redshift Survey
~24000 AGN1
20 years after…and two order of magnitude larger samples
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
€
Ψ(L) =Ψ*
(L /L*)β h + (L /L*)β l
€
Ψ(M) =Ψ '*
100.4[M −M * ][β h +1] +100.4[M −M * ][βl+1]
Schmidt & Green 83, ~200 AGN1
Boyle, Shanks & Peterson 88, ~700 AGN1
LF & Cristiani 97 ~ 1200 AGN1
20 years of evolution of the evolutionof the QSO (AGN1) luminosityfunction
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. 2004NLR H and [OIII] LF
Schmidt, Schneider & Gunn 1995
Fan+04 SDSS
High redshift QSO (AGN1) densityoptical (grism) selection
See also Fontanot+07
High redshift QSO (AGN1) densityradio selection
Dunlop & Peacock 90Miller, Peacock & Mead 90
●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
Often rapidly varying:small emission region
Broad spectral energy distribution
High-excitation emission
Before XMM and Chandra:the X-ray LF from ROSAT (Miyaji, Hasinger, Schmidt 2000)0.5-2keV --> mainly AGN1Previous works from Einstein data:e.g. Della Ceca+92
X-ray backgroundthe need for the AGN2/absorbed population
Comastri, Setti, Zamorani, Hasinger 1995
X-ray backgroundthe need for the AGN2/absorbed population
AGN1
AGN2-thin
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 2 AGN
Type 1 AGN
There is rough correspondencebetween optical AGN1/AGN2 classificationand column densities
First Spectroscopic identification of Chandra sources
Fiore, LF, Vignali et al. (2000)
XBONG(X-ray Bright Optically Normal Galaxy)
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
NH column density distribution
X-ray absorption dependent sky-coverage
Luminosity Dependent Density Evolution (LDDE)
(see previous results fromUeda et al. 2003)
Lower luminosity AGNpeak at lower redshifts:DOWNSIZING(see models of galaxy andAGN formations)
LF, Fiore, Comastri+05
Marconi+04
X-ray AGN LF
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
0.5-2 keV: Hasinger, Miyaji, Schmidt 05
See also:-Ueda+03 (selection effects included)-Barger+05-Silverman+08-Della Ceca+08-Ebrero+09 (selection effects included)-Yencho+09-Aird+10
Brusa+09
LDDE found also for optically selected AGN1once the faint end of the LF is probed
Bongiorno, Zamorani+08
See also e.g. Fontanot+07, Shankar & Mathur 07
Downsizing in all bandsHopkins, Richards & Hernquist (2007)
Bongiorno+10 find LDDE also for the AGN2 [OIII] LF
General Evolutionary Trends
• And a calculator: www.cfa.harvard.edu/~phopkins/Site/qlf.html
Hopkins, Richards & Hernquist (2007)
The fraction of absorbed AGN as function of LX and z
*) Assuming no luminosity and redshift dependences
assumed *)
predicted
DECREASE WITH LUMINOSITYEarlier 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).
INCREASE WITH THE REDSHIFT
LF, Fiore, Comastri+05
- 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 fraction of absorbed AGN as function of LX and z
The decrease of absorbed AGN with increasing luminosity(possible explanations)
Lamastra, Perola & Matt (2006)
The Receding Torus Model: the opening angleof the torus increases with ionizing luminosity(e.g. Simpson 1998; Lawrence 1991;Grimes et al. 2003)
Model 1 Model 2
The gravitational effects of the BH/Bulge on the molecular gas disk of galaxies
Best fit: assuming L and z dependence
The fraction of absorbed AGN as function of LX and z
L
z
We confirm the evidences of a decrease of the fraction of absorbed AGN with luminosity andfind for the first time an increase of absorbed AGN with redshift.
LF, Fiore, Comastri+05
1815 AGN with intrinsic LX>1042 erg/s
The fraction of absorbed AGN as function of LX and z
Melini, Thesis RmTre, 2009
Z~0.3Z~0.3
Z~0.7Z~0.7Z~1.2Z~1.2
Z~1.8Z~1.8
Z~2.5Z~2.5
Lx~43Lx~43
Lx~44Lx~44
Lx~45Lx~45
Confirmed by: Treister & Urry 06, Ballantyne 06, Hasinger+08, Della Ceca+08See discussion on possible selection effects in Akylas+06
The very hard (14-195 keV) XLF
See also: Beckmann+06 and Sazonov+07using INTEGRAL (20-40 keV)
Tueller, Mushotzky+08 (SWIFT/BAT)
A sample of~500 SWIFT/BATAGN are going tobe investigatedby the INAF/Breraand INAF/Palermo-IASFgroups
Tueller, Mushotzky+08 (SWIFT/BAT)
CT about 20%
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 theselection effects the NH
distribution is fully compatible with [OIII]selected samples(e.g. Risaliti+99)
Estimate a fractionof 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
Marconi et al. (2004)
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-raybackground are the “fossil” integrated result of theAGN evolution, i.e. of the total of accreted mass andof the total energy released in the Universe via accretion
z=0 BH mass functionX-ray background
Integrated history of accretion
Integrated luminosity history
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
0
0
bol
2
bol
20 0 0
( , ) : local BH mass function,
( , ) : QSO luminosity function,
(1 ): efficiency,
(1 )( , ) d d ( , );
local accreted
.
M
M
t
n M t
L t
LM
c
LMn M t dM t L L t
c
ψ
εε
ε
ε ψε
∞ ∞
−=
−=∫ ∫ ∫
&
Total mass density accreted = total local BH mass density
Accretion history of the Universe
Luminosity density
Mass density in BH
Marconi et al. (2004): 4.6 (+1.9;-1.4) M๏ Mpc-3
McLure & Dunlop (2004): 2.8 (+/- 0.4) M๏ Mpc-3
Accretion rate density
Bolometric correction (Marconi et al. 04)
ε=0.1, radiative efficiency
Luminosity density evolution
BH mass density evolution
The history of BH mass density accretedduring quasar phase
Yu and Tremaine 2002
QSO mean lifetime
● The mean lifetime of QSOs is comparable to the Salpeter time (the time for a BH accreting with the Eddington luminosity to e-fold in mass).
'0
'
)( 0
)d,(
)d(d)(
0
MtMn
tL,tLM
M M
ML
t
∫∫ ∫
∞
∞
=ψ
~(3-13)107 yr
Expanding Soltan’s Argument
Fitting QLF with local BHMF
Evidences for missing SMBH While the CXB energy density providesa 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.
Gilli et al. 2007
Marconi 2004-2007Menci , Fiore et al. 2004, 2006, 2008
43-44
44-44.5
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
● 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
Dusty torus
Cen
tral eng
ine
Matute, LF, Pozzi+06
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
IR surveysDifficult 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
Martinez-Sansigre+05
Georgantopulos+08
Sacchi, LF, Feruglio+09
Stern+05 selection
Lacy+04 selection
MIR selection of AGN
Gruppioni+08
Gruppioni+08
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 orderto measure the column densities
SED library from Polletta+07
MIR selection of CT AGN
CDFS X-rayHELLAS2XMM GOODS 24um galaxies
COSMOS X-ray COSMOS 24um galaxies
R-K
Fiore+08 Fiore+09
Open symbols = unobscured AGNFilled symbols = optically obscured AGN* = photo-z
see also Daddi+07
MIR AGNsFiore+08+09
Stack of Chandra images of MIR sources not directly directly detected in X-rays
F24um/FR>1000 R-K>4.5logF(1.5-4keV) stacked sources=-17 @z~2 logLobs(2-8keV) stacked sources ~41.8log<LIR>~44.8 ==> logL(2-8keV) unabs.~43Difference implies logNH~24
Sacchi, LF+09 VLT observationsshowed that about 70% of the300<X/R<1000 DOGs have anAGN optical spectrum
Sacchi, LF, Feruglio+09See also Lanzuisi+09
Flu
x 0
.5-1
0 k
eV
(cg
s)
Area
HELLAS2XMM 1.4 deg2
Cocchia et al. 2006Champ 1.5deg2Silverman et al. 2005
XBOOTES 9 deg2
Murray et al. 2005, Brand et al. 2005
XMM-COSMOS 2 deg2
-16
-15
-14
-13
CDFN-CDFS 0.1deg2 Barger et al. 2003; Szokoly et al. 2004
EGS/AEGIS 0.5deg2
Nandra et al. 2006
SEXSI 2 deg2 Eckart et al. 2006
C-COSMOS 0.9 deg2
E-CDFS 0.3deg2
Lehmer et al. 2005
ELAIS-S1 0.5 deg2
Puccetti et al. 2006
Pizza Plot
Brusa+10
AGN host galaxies
Obscured (no AGN1) AGN in themost massive and redder galaxies
A significant fraction of obscuredAGN live in massive, dusty star-forminggalaxies with red optical colors
AGN preferentially residein the red sequence andin the “green valley”(Nandra+07, Silverman+08,Hickox+09)
Z>3 AGN countsLower bound: 22 spectro-zUpper-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 outTightest constraints to date (largest and cleanest sample)
Models: Gilli, Comastri & Hasinger 2007, A&A
Space densities
Red curve: predictionslogLx>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
La Franca+05
La Franca+05 (& Brusa+09 at z>2.7)
Brusa+09
X
L 1.4GHz/LX
P(R| LX, z) from LF, Melini & Fiore, ApJ, subm
=
The radio LF and the sub-mJy radio counts
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 decreasingluminosity
-Integrating the AGN LF, the CXRB and the local BH massfunction 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 anAGN like SED in the MIR.
-SWIFT and INTEGRAL have not found column densities significantlydifferent 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 roughagreement with the AGN1 evolution in the optical (and radio)
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