Transcript Diapositiva 1

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
SMBH & galaxies co-evolution
Supermassive Black Holes (SMBH, MBH=106-109 M) are a ubiquitous
Tightoflink
between
the growth
SMBH &(AGN
phase)
constituent
spheroids
in nearby
galaxies of
(Kormendy
Richstone
1995)
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. 2000, 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
The Evolution of the MBH-M* relation
stellar mass assembly
BH growth
Haring & Rix 2004
The MBH-M* relation at high redshift
Peng et al. 2006
McLure et al. 2006
Maiolino et al. 2009
Merloni et al. 2010
Decarli et al. 2010
Alexander et al. 2008
(1+z)
M BH (z)/M* (z)
Γ(z) 
M BH (z  0)/M* (z  0)
Detailed predictions based on semi-analytic model
(Menci et al. 04,05,06,08)
+
gas cooling, star
formation
SN feedback,…
DM merging trees
• DM merging trees: Monte Carlo realizations
+
SMBH growth, AGN,
AGN feedback
• 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
The evolution of Dark Matter Haloes
• 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
Phase 1
Last major merging at z≈3 for M≈3X1012 M
At later times, merging rate declines
Accretion of much smaller clumps
Phase 2
Springel et
al. 2005
Star formation
Menci et al. 2005, 2006
Two channels of star formation may convert the cold gas into stars:
1. Quiescient star formation
.
m* 
mcool M 
r
 * ( M )   SF disk
vdisk
 * (M )
.
Cf. with
Kennicutt law
1.4
m*
m 
  cold 
Area  Area 
.
m*  mcold  
mcold
m
 cold
char.tim e  dyn
2. Starburst driven by (major+minor) merging and fly-by events (time scale
10-50 Myr, SFR up to 1000 M/yr)
Supernovae feedback: ESN
Δm*
 1051 ηIMF ε 0
erg
M
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
Blue galaxies
Red galaxies
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
τint  rd /vd
Fraction of accreted gas
Interaction rate
Larger fraction of
accreted gas for
-massive haloes
-high z (m’/m≈1)
Higher interaction rate at high z
AGN feedback: associated to the active, accretion phase
E   AGNc 2macc
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
Testing the model
Local stellar mass function
data points:
2dF survey
(Cole et al. 2001)
2MASS survey
(Bell et al. 2003)
Tully-Fisher relation
Bimodal color distribution
shaded region:
Mathewson et al
1992
Willik et al. 1996
Giovanelli et al.
1997
u-r color
B-band luminosity function
AGN luminosity function
z=0.1
data points:
Balnton et al 2000
Madgwick et al. 2002
Zucca et al. 1997
data points:
La Franca et al. 2005
MBH-σ relation
The predicted MBH-M* relation
z=0.1
data points:
Haring & Rix 2004
Marconi & Hunt 2003
z=4
data points:
high-z QSO
Maiolino et al. 07
Riechers et al. 08, 09
Walter et al. 04
Barth et al. 03
Dietrich & Hamann 04
Shields et al. 07
Riechers et al. 09
Evolutionary paths
followed by BH with
MBH(z=0)>1010 M
Lamastra et al. 2010 MNRAS
Selecting massive BHs at high z
Contour plots: fraction of objects with a given Γ(z)
from 0.01 (lightest) to 0.1 (darkest)
Star formation
BH accretion
M BH (z)/M* (z)
Γ(z) 
M BH (z  0)/M* (z  0)
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. 2010 MNRAS
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. 2010 MNRAS
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)
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. 2010 MNRAS
Mass dependence of Γ(z)
Lamastra et al. 2010 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
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≥1044.5 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
NO AGN feedb
In the absence of AGN feedback
a sizeble fraction of large-mass
galaxies has blue colors
AGN feedb
The low redshift descendants of SMGs are predicted to have BH with
MBH=108-109 M, in agreement with the independent finding of Alexander
et al. 2008 based on the larger number density of SMGs compared to
that of local galaxies hosting BH with MBH>109M