1. Black Hole - Stellar Mass
The Building Up of the
Black Hole - Stellar Mass
Relation
Alessandra Lamastra
collaborators:
Nicola Menci1, Roberto Maiolino1, Fabrizio Fiore1, Andrea Merloni2
1 INAF - Osservatorio Astronomico di Roma
2 Max-Planck-Institut fur Extraterrestriche Physik

2. SMBH & galaxies co-evolution
Supermassive Black Holes (SMBH, MBH= M) are a ubiquitous constituent of spheroids in nearby galaxies (Kormendy & Richstone 1995)
Tight link between the growth of SMBH (AGN phase) and the formation of the host galaxy
In the local Universe the black hole mass strongly correlates with the properties of the spheroidal component of the host galaxy (Magorrian et al. 1998, Ho 1999, Gebhardt et al , Ferrarese & Merritt 2000, Graham et al. 2001)
Which is the physical nature of the SMBH-galaxy connection?
MBH-M*
MBH-σ*
MBH-Lbulge
Which are the relative time scales for star formation and for SMBH growth?
How and when the AGN emission affects the galaxy properties?
Haring & Rix 2004
Tremaine et al. 2002
Marconi & Hunt 2003

3. The Evolution of the MBH-M* relation
stellar mass assembly
BH growth
Haring & Rix 2004

4. The MBH-M* relation at high redshift
(1+z)
Peng et al. 2006
McLure et al. 2006
Maiolino et al. 2009
Merloni et al. 2010
Decarli et al. 2010
Alexander et al. 2008

5. + + Detailed predictions based on semi-analytic model
(Menci et al. 04,05,06,08) + +
gas cooling, star formation
SN feedback,…
DM merging trees
SMBH growth, AGN, AGN feedback
DM merging trees: Monte Carlo realizations
Dynamical processes involving galaxies within DM haloes
Cooling, Disc properies, Star formation and SNae feedback
Starbursts triggered by merging and fly-by events
Growth of SMBH from BH merging + accretion of galactic gas destabilized by galaxy encounters (merging and fly-by events)
Feedback from the AGN associated to the active, accretion phase
Rate of encounters
Fraction of galactic gas accreted by the BH
Stellar content of the host galaxies
duty cycle
Physical, non parametric
Model.Computed from galactic and orbital quantities

6. Properties of DM merging trees
The evolution of Dark Matter Haloes
Springel et al. 2005
Galaxy formation and evolution are driven by the collapse and growth of dark matter (DM) haloes, which originate by gravitational instability of overdense regions in the primordial DM density field
The primordial DM density field is taken to be a random, Gaussian density field with Cold Dark Matter (CDM) power spectrum within the “concordance cosmology” (Spergel et al. 2007).
Properties of DM merging trees
Initial (z≈4-6) merging events involve
small clumps with comparable size
High merging rate
Last major merging at z≈3 for M≈3X1012 M
Phase 1
At later times, merging rate declines
Accretion of much smaller clumps
Phase 2

7. z>2 z<2 Star formation
Menci et al. 2005, 2006
Two channels of star formation may convert the cold gas into stars:
Quiescient star formation
Cf. with Kennicutt law
Starburst driven by (major+minor) merging and fly-by events (time scale Myr, SFR up to 1000 M/yr)
Blue galaxies
Red galaxies
Supernovae feedback:
Frequent galaxy interactions
Rapid cooling (high gas density)
Starbursts with large fraction of
gas converted into stars
Drop of interaction rate
Decline of cooling rate
Quiescent and declining star formation
z>2
z<2

8. Accretion onto SMBH and AGN emission
(Menci et al. 2006,2008)
The BH accretion is triggered by galaxy interactions (merging and fly-by events)
Black hole accretion rate
Fraction of accreted gas
Larger fraction of accreted gas for
massive haloes
high z (m’/m≈1)
Interaction rate
Higher interaction rate at high z
AGN feedback: associated to the active, accretion phase
Hydrodynamic N-body simulations
(e.g. Di Matteo et al. 2005, Hopkins et al. 2006, Springel et al. 2005)
Galaxy mergers as triggers for BH accretion
Role of the AGN feedback

9. Testing the model MBH-σ relation Local stellar mass function
data points:
2dF survey
(Cole et al. 2001)
2MASS survey
(Bell et al. 2003)
Tully-Fisher relation
shaded region:
Mathewson et al 1992
Willik et al. 1996
Giovanelli et al. 1997
Bimodal color distribution
u-r color
MBH-σ relation
AGN luminosity function
B-band luminosity function
data points:
z=0.1
Balnton et al 2000
Madgwick et al. 2002
Zucca et al. 1997
data points:
La Franca et al. 2005

10. The predicted MBH-M* relation
z=0.1
z=4
local relation
local relation
data points:
Evolutionary paths followed by BH with MBH(z=0)>1010 M
data points:
high-z QSO
Haring & Rix 2004
Maiolino et al. 07
Marconi & Hunt 2003
Riechers et al. 08, 09
Walter et al. 04
Barth et al. 03
Dietrich & Hamann 04
Shields et al. 07
Riechers et al. 09
Lamastra et al MNRAS

11. Selecting massive BHs at high z
Contour plots: fraction of objects with a given Γ(z)
Star formation
from 0.01 (lightest) to 0.1 (darkest)
BH accretion
Γ >1 when we select MBH >109 M at z≥4
Galaxies formed in biased, high density regions undergo major merging events at high redshifts. At z ≲ 2.5 interaction-driven AGN feeding drops while quiescent star formation still builds up stellar mass bringing Γ→1
Lamastra et al MNRAS

12. Selecting intermediate-mass objects at z=1-2
Contour plots: fraction of objects with a given Γ(z)
from 0.01 (lightest) to 0.1 (darkest)
Galaxies formed in less biased regions of the primordial density field:
lower interaction rate at z≳4
The excess Γ>1 is less pronounced
Observations by Merloni et al. 2010: log LX/erg s-1>44.5
Lamastra et al MNRAS

13. Selecting gas-rich, star forming galaxies at z=2-3
Contour plots: fraction of objects with a given Γ(z)
from 0.01 (lightest) to 0.1 (darkest)
local relation
datapoints: Alexander et al. 2008
Adopted selection critera consistent with those adopted by Alexander et al. 08
Gas Fraction ≥ 0.7 (see Tacconi et al. 06, 08; Swinbank et al. 08) SFR ≥ 100M/yr
Γ(z)<1 for galaxies which retained a large gas fraction at z=2-3 (galaxies originated from merging histories characterized by less prominent high-z interactions)
Lamastra et al MNRAS

14. Mass dependence of Γ(z)
Lamastra et al MNRAS
Downsizing in the assembly of BH masses
Massive local galaxies have formed preferentially through path passing above the local MBH-M* relation
5% of the final mass
50% of the final mass
90% of the final mass
Marconi et al. 2004

15. Summary
Interaction-driven fueling of AGNs within Cosmological galaxy formation models yields:
Γ(z)>1 for massive galaxies at high redshift (i.e., when merging histories characteristic of biased, high-density regions of the primordial density field are selected)
Γ≃2 for luminous (Lbol≥ erg/s) QSO at z=1-2
Γ≃4 for massive (MBH≥109 M) in QSOs at z≳4
Γ(z)<1 for galaxies which retained a large gas fraction at z=2-3 (i.e., which did not convert the whole gas content into stars at high redshifts)
Γ≃(0.3-1) for SMG-like galaxies hosting active AGNs (LX≥1043 erg/s, large SFR and gas fraction ). These evolve to local galaxies with masses MBH < 109 M
At any given z, Γ(z) is predicted to increase with BH mass
Corresponds to a ‘’downsizing’’ in the assembly of BH masses
Measuring Γ(z) for an unbiased sample of AGN can provide crucial constraints on interaction-driven fueling scenarios for the growth of SMBHs in a cosmological context

19. In the absence of AGN feedback a sizeble fraction of large-mass
NO AGN feedb
AGN feedb
In the absence of AGN feedback
a sizeble fraction of large-mass
galaxies has blue colors

20. The low redshift descendants of SMGs are predicted to have BH with MBH= M, in agreement with the independent finding of Alexander et al based on the larger number density of SMGs compared to that of local galaxies hosting BH with MBH>109M