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

MBH-M* MBH-σ* MBH-Lbulge

Haring & Rix 2004 Tremaine et al. 2002 Marconi & Hunt 2003

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)

Supermassive Black Holes (SMBH, MBH=106-109 M) are a ubiquitous constituent of spheroids in nearby galaxies (Kormendy &

Richstone 1995)

SMBH & galaxies co-evolution

Tight link between the growth of SMBH (AGN phase) and the formation of the host galaxy

Which is the physical nature of the SMBH-galaxy connection?

Which are the relative time scales for star formation and for SMBH growth?

How and when the AGN emission affects the galaxy properties?

The Evolution of the MBH-M* relation

Haring & Rix 2004

BH growth

stellar mass assembly

The MBH-M* relation at high redshift

0)(z0)/M(zM

(z)(z)/MMΓ(z)

*BH

*BH

Peng et al. 2006

McLure et al. 2006

Merloni et al. 2010

Decarli et al. 2010

Alexander et al. 2008

Maiolino et al. 2009

(1+z)

• 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

Detailed predictions based on semi-analytic model(Menci et al. 04,05,06,08)

+ +DM merging trees

gas cooling, star formation

SN feedback,…

SMBH growth, AGN, AGN feedback

Rate of encountersFraction of galactic gas accreted by the BHStellar content of the host galaxiesduty cycle

Physical, non parametric Model.Computed from galactic and orbital quantities

The evolution of Dark Matter Haloes

Initial (z≈4-6) merging events involve small clumps with comparable size

High merging rate

Last major merging at z≈3 for M≈3X1012 MAt later times, merging rate declines

Accretion of much smaller clumps

Phase 1

Phase 2

• 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

Springel et al. 2005

Two channels of star formation may convert the cold gas into stars:

2. Starburst driven by (major+minor) merging and fly-by events (time scale 10-50 Myr, SFR up to 1000 M/yr)

Supernovae feedback:

Frequent galaxy interactionsRapid cooling (high gas density)Starbursts with large fraction of gas converted into stars

Drop of interaction rateDecline of cooling rateQuiescent and declining star formation

z>2

z<2

Menci et al. 2005, 2006

1. Quiescient star formation

ergM

Δmεη10E *

0IMF51

SN

Blue galaxies

Red galaxies

)(*

*

.

M

Mmm cool

disk

diskSF v

rM )(*

dyn

coldcoldcold

cold

m

timechar

mmm

Area

m

Area

m

.

.

*

4.1.

*

Cf. with Kennicutt law

Star formation

Accretion onto SMBH and AGN emission

•The BH accretion is triggered by galaxy interactions (merging and fly-by events)Black hole accretion rate

Fraction of accreted gas

Interaction rate

Larger fraction of accreted gas for -massive haloes -high z (m’/m≈1)

(Menci et al. 2006,2008)

ddint /vrτ

Higher interaction rate at high z

AGN feedback: associated to the active, accretion phase accAGN mcE 2

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 modelLocal 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

1992Willik et al. 1996Giovanelli et al.

1997

u-r color

Bimodal color distribution

B-band luminosity function

data points:

z=0.1

Balnton et al 2000Madgwick et al. 2002

Zucca et al. 1997data points:

La Franca et al. 2005

AGN luminosity function MBH-σ relation

The predicted MBH-M* relation

Haring & Rix 2004

Marconi & Hunt 2003

Lamastra et al. 2010 MNRAS

Evolutionary paths followed by BH with

MBH(z=0)>1010 M high-z QSO

z=0.1 z=4

data points:

local

relat

ion

loca

l re

latio

n

data points:

Maiolino et al. 07

Walter et al. 04 Riechers et al. 08, 09

Barth et al. 03Dietrich & Hamann 04Shields et al. 07Riechers et al. 09

Selecting massive BHs at high z

Γ >1 when we select MBH >109 M at z≥4

Lamastra et al. 2010 MNRAS

Star formation

BH accretion

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

0)(z0)/M(zM

(z)(z)/MMΓ(z)

*BH

*BH

Contour plots: fraction of objects with a given Γ(z)

from 0.01 (lightest) to 0.1 (darkest)

Selecting intermediate-mass objects at z=1-2

Galaxies formed in less biased regions of the primordial density field: lower interaction rate at z≳4

The excess Γ>1 is less pronounced

Lamastra et al. 2010 MNRAS

Observations by Merloni et al. 2010: log LX/erg s-1>44.5

Contour plots: fraction of objects with a given Γ(z)from 0.01 (lightest) to 0.1 (darkest)

Selecting gas-rich, star forming galaxies at z=2-3

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)

datapoints: Alexander et al. 2008

Lamastra et al. 2010 MNRAS

from 0.01 (lightest) to 0.1 (darkest)

Contour plots: fraction of objects with a given Γ(z)

local r

elation

Mass dependence of Γ(z)

Massive local galaxies have formed preferentially through path passing above the local MBH-M* relation

Lamastra et al. 2010 MNRAS

5% of the final mass

50% of the final mass

90% of the final mass

Marconi et al. 2004

Downsizing in the assembly of BH masses

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=1-2Γ≃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 AGN feedb

In the absence of AGN feedback a sizeble fraction of large-mass

galaxies has blue colors

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