1. AGN evolution: a panchromatic view
Andrea Merloni
MPE
Merloni, FERO 8, September 2016

2. Merloni, FERO 8, September 2016
Introduction
What FERO is about:
Detailed physical modelling of the inner region of AGN
A few bright sources, lots of photons, extensive observational campaigns
Measuring BH spin, inner disc/corona geometry, energetics
What my work is about:
X-ray and multiwavelength surveys
Many sources, few photons, “snapshots”
Measuring long term (cosmological) evolution of AGN
Merloni, FERO 8, September 2016

3. Merloni, FERO 8, September 2016
Outline
X-ray surveys and the history of accretion
Soltan argument and the efficiency of accretion
What do we learn from “evolutionary studies” of AGN about their inner working?
The first black holes (time permitting)
Merloni, FERO 8, September 2016

4. Black Holes in the local Universe
Ω*BH≈710-5 [Fukugita & Peebles (2007)]
Stellar physics, SN explosions, GRB
Sgr A*
M87
ΩSMBH≈2.710-6
Accretion over cosmological times,
Active Galactic Nuclei, galaxy evolution
Ωbaryon≈4.510-2 ; Ωstars≈2.510-3
Merloni, FERO 8, September 2016

5. Merloni, FERO 8, September 2016
Accreting black holes
Chandra Deep Field South:
The deepest X-ray image of the sky ever taken (Xue et al. 2011)
Every dot is a (supermassive) black hole!
Merloni, FERO 8, September 2016

6. A logarithmic view of the AGN-galaxy connection
Binding Energies
Eb,≈4  1048 ergs
Eb,BH,8≈1061 ergs
Eb,gal,11≈1059 ergs
Eb,Coma≈1064 ergs
I do not have time now to enter into a detail discussion of the various physical processes taking place at different scales, but I just want to emphasize that there are about 8 orders of magnitude difference between the scale where most of the gravitational energy of the accretion matter is released (either as radiation or as bulk motion of powerful relativistic jets) and the size of a galaxy.
Right in the middle, is the scale where the gravitational pull of the black on the surrounding gas begins to be felt, here represented by a black dashed line, is where both fuelling rate and obscuration level are fixed, crucially determining the observational appearance of a growing black hole.
Although this may sound as a nightmare for a purely numerical approach, observations at different wavelengths do offer the chance to resolve different scales, and to achieve a high-dynamic range view of the AGN phenomenon.
A. Merloni, ESO graphics, 2010
Merloni, FERO 8, September 2016

7. Spectral Energy Distribution (SED)
Merloni, FERO 8, September 2016
Elvis et al. 1994

8. Differences between QSOs and galaxies
Bruzual and Charlot 2003
Nakos et al. 2009
Merloni, FERO 8, September 2016

9. 1. 2. 3. SMBH census is a matter of contamination
Richards+ 2006, Lusso+ 2011 3. 2.
Setti&Woltjer, Comastri+ 1995, Gilli+2007, Treister+ 2009, Moretti+ 2011
AGN dominate XRB, but contribute only to ~10% of IRB
XRB itself is dominated by obscured (and heavily obscured) AGN
Merloni, FERO 8, September 2016

10. Biases in optical AGN surveys: Obscuration and galaxy dilution
Most of the optical/NIR SEDs of XMM-COSMOS AGN can be explained as a combination of a pure AGN extinguished and/or contaminated by the host galaxy.
Merloni, FERO 8, September 2016

11. AGN selection basics: contrasts
Assume: (1) MBH/M*=A0 ; (2) logSFR = α(z)(logM∗ −10.5)+β(z)
(BH-galaxy scaling relation)
(“Main sequence” of star formation)
Eddington rate λlimit (z=1, z=0)
(0.13, 0.015)
(0.025)
(2×10-4, 2×10-5)
Merloni (2016)
Merloni, FERO 8, September 2016

12. Merloni, FERO 8, September 2016
Number counts
Lehmer et al. 2012;
Brandt & Alexander 2015
Merloni, FERO 8, September 2016

13. Merloni, FERO 8, September 2016
AGN densities
Neq [deg-2]
Feq
Fdeep (m)
Fwide
Awide [deg2]
Radio [1.4 GHz]
~1200
~100μJy
10 μJy
2.5 mJy
30,000 [NVSS]
IR color ~
50-100μJy
1-5 μJy
0.1 mJy
41,251 [WISE]
Opt. QSO color
~150
4μJy
(r~22.4)
~20 nJy (r~28)
~10,000 [SDSS]
X-ray keV
~20,000
5x10-18
10-17 cgs
3 x cgs
41,251 [ROSAT]
X-ray 2-10 keV
>10,000
~10-18
4 x cgs
5 x cgs
41,251
[HEAO-1]
X-ray >10 keV
>0.03
<1.3x10-11
3 x cgs
1.3 x cgs
[Swift-BAT]
Flux (and AGN number density) where nAGN=ngalaxies
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14. Merloni, FERO 8, September 2016
X-rays identify black holes in their growth phase
Most of the accretion in the universe is obscured
SMBH and their host galaxies co-evolve
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15. Merloni, FERO 8, September 2016
The deep X-ray sky
COSMOS field, 2 deg2 (Scoville+07)
XMM 1.55 Ms ~1e-15 cgs
(Hasinger+07, Cappelluti+07,09)
Chandra 1.8 Ms ~2e-16 cgs
(Elvis+09, Puccetti+09)
CDFS 1-2-4Ms ~0.1 deg2, ~4e-17 cgs
(Giacconi+ 2002, Luo+ 2008, Xue+2011)
XMM/CDFS 3Ms (Comastri+2011)
Public fields, resource for community
soft keV
medium keV
hard keV
Merloni, FERO 8, September 2016

16. Resolving the background: XLF
Need to explore a wide range in Luminosity AND redshift
Need to understand selection function
Combining different surveys
Buchner et al. 2015; See also Ueda et al. 2014; Aird et al. 2015; Myiaji et al. 2015
Merloni, FERO 8, September 2016

17. Bayesian X-ray spectral analysis
Bucher et al 2014
Merloni, FERO 8, September 2016

18. Bayesian X-ray spectral analysis
Bucher et al 2014
Merloni, FERO 8, September 2016

19. X-ray luminosity function evolution
Aird et al 2015
Merloni, FERO 8, September 2016

20. X-ray Background resolved
obscured
(Compton thin)
unobscured
obscured
(Compton thick)
ULX
HMXB NS
Merloni, FERO 8, September 2016
Comastri & Setti 1995; Gilli et al. 2007; Treister et al. 2009; Akylas et al. 2012; Aird et al. 2015

21. Merloni, FERO 8, September 2016
Densities evolution
Buchner et al 2015
Merloni, FERO 8, September 2016

22. Panchromatic Luminosity Functions
B-band QSOs
IR-selected AGN
0.5-2 keV AGN
2-10 keV AGN
Steep Spectrum radio AGN
Flat Spectrum radio AGN
Hopkins et al. (2007)
Merloni, FERO 8, September 2016

23. Panchromatic Luminosity Functions
Hard X-rays provide by far the most
complete census of AGN activity
See Hopkins et al. (2007);
Marconi et al. (2004)
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24. Merloni, FERO 8, September 2016
Densities evolution
Aird et al 2015
Merloni, FERO 8, September 2016

25. BH accretion vs. Star Formation
Aird et al 2015
Merloni, FERO 8, September 2016

26. Understanding the mass function evolution
BH mass can only increase*
As opposed to galaxies, BHs do not transform into something else as they grow**
BHs are like teenagers: they let us know very clearly when they grow up (AGN)
*Kicked BH after mergers can introduce a loss term in the continuity equation
**Merging BH alter the Mass function
Merloni, FERO 8, September 2016

27. Integral constraint: the Soltan argument
Soltan (1982) first proposed that the mass in black holes today is simply related to the AGN population integrated over luminosity and redshift
Fabian and Iwasawa (1999) ~0.1; Elvis, Risaliti and Zamorani (2002)  >0.15;
Yu and Tremaine (2002) >0.1; Marconi et al. (2004) 0.16>  >0.04;
Merloni, Rudnick, Di Matteo (2004) 0.12>  >0.04; Shankar et al. (2007)  ~0.07
Merloni, FERO 8, September 2016

28. Most (~3/4) of SMBH is “obscured”
24%
41%
εrad=0.1
Merloni, FERO 8, September 2016
Buchner et al. 2015; Merloni 2015

29. Constraints on efficiency rad
0=BH,0/(4.2×105)
i=BH(z=zi)/BH,0
(Input from seed BH formation
models needed!)
CT=BH,CT/BH,0
(Fractional Mass density of SMBH grown in a Compton Thick, heavily obscured phase)
lost=BH,lost/BH,0
(Mass density of SMBH ejected from galactic nuclei due to GW recoil after mergers)
rad/(1-rad) ≈ 0.075/[0 (1-CT-i +lost)]
Merloni and Heinz 2008
Volonteri et al. 2013
Merloni, FERO 8, September 2016

30. Relation between AGN evolution and accretion physics
Most ‘Soltan’-type arguments assume a fixed, constant radiative efficiency. What about spin evolution?
Combining multi-wavelength (Opt vs X-ray) surveys requires varying X-ray-to-optical ratios (as a function of luminosity and/or Eddington ratio). What drives this?
Merloni, FERO 8, September 2016

31. Disc-corona coupling problems
The problem of self-consistent physical generation of the “corona” is intimately linked to that of the nature of viscosity
We still do not understand why soft-state discs (with very little coronae) in XRB are stable!
Merloni, FERO 8, September 2016

32. Merloni, FERO 8, September 2016
Thanks!
Merloni, FERO 8, September 2016