Massive Black Holes and their host galaxies

Massive Black Holes and their host galaxies

Marta Volonteri Institut d’Astrophysique de Paris

1. (Massive) black holes, AGN and quasars - difference between stellar and supermassive black holes - active vs quiescent BHs, including the Milky Way case

2. Massive black holes and galaxies - mass measurement of BH masses - local samples and correlations

3. Massive Black Hole formation - high-z quasars - seed BHs

4. Cosmic evolution - accretion vs mergers - Soltan's argument - BH-host vs z - Triggering of AGN activity - role of feedback

High-redhift quasars Sloan Digital Sky Survey: SDSS pioneered the optical selection of z=6 quasars with the first large area survey in the i’ and z’ filters Shallow-wide survey: find rare bright quasars

SDSS Deep finds 11 fainter quasars over 300 sq deg Fan et al.(2000-2006)

Jiang et al.(2008;2009)

courtesy of C. Willott

High-redhift quasars Canada-France High-z Quasar Survey: CFHQS is a colour-selected 5.8<z<6.5 quasar survey using imaging from CFHT

Deep field: search for lower luminosity sources


X-rays require deep optical/NIR to determine which X-ray sources are at high-z

(but less sky area needed) . •  Low-luminosity quasar at z=5.2 in GOODS-N (Barger et al.2003) •  Compton-thickAGN at z=5 in GOODS-S (Gilli et al.2011) •  NoAGN at z>6 identified in deepest X-ray surveys. •  Faintest CFHQS quasar located in SXDS XMM survey - undetected to •  L0.5−4.5 < 5x1044 erg s-1,but only expect L0.5−4.5 = 1044 erg s-1

X-ray selection of AGN at z=6


Radio-loud quasars at z=6

SKADS Wilman et al.(2008) Jarvis & Rawlings (2004)

About 10% of SDSS and CFHQS quasars are radio-loud.

Some FIRST z>6 quasars discovered after isolation by i-z colour selection in small sky areas McGreer et al.(2006) Ziemann et al.(2011)


Radio-loud quasars at z=6: blazars •  Blazars are radio-loud Active Galactic Nuclei, whose jet is

pointing as us: viewing angle smaller than θ<1/Γ, whereΓ is the bulk Lorentz factor of the jet.

•  Then for each detected blazars there are other 2Γ2=450(Γ/15)2 misaligned sources with same intrinsic properties, but not detectable as such

•  Hard X-ray selection optimal for detecting high-z blazars because of SED => Swift BAT

•  Include also gamma-ray detections => Fermi/LAT survey => ϒ–rays

M. Volonteri, Brera 2013

High-z blazars

Swift/BAT selected L>1047erg/s Ajello et al. 2009


High-z blazars Heavy and active SMBHs in BAT & LAT: (i) M > 109M⊙ (ii) (Ld/LEdd) > 0.1

Ghisellini et al. 2013

This population is still unseen in optical + radio selection. Why? (See Sbarrato et al. 2012, 2013 though)


Quasar luminosity function

Willott et al.(2010) Assuming Eddington ratio distribution and duty cycle (both ~ unity) can convert into a mass function


Quasar luminosity function at z=6 derived from 16 CFHQS and 24 SDSS quasars

•  Black hole mass function has evolved by ~104 from z=6 to z=0 •  Stellar mass function has evolved by ~102 from z=6 to z=0

MBH mass function at z=6 vs z=0

Local BH MF (Shankar et al.2009) Local stellar MF (Baldry et al.2008)

z=6 stellar MF (Stark et al.2009)

z=6 BH MF (Willott et al.2010b)

Mstellar axis shifted by 4x10-3 from MBH

courtesy of C. Willott Willott et al.(2010)

Quasars have been detected at very large distances, corresponding to a very young age of the Universe.

As massive as the largest SMBHs today, but when the Universe was

0.75 Gyr old!

WHEN do you make the first massive black holes?

Gultekin et al. 2009

The farthest quasar currently known, ULASJ112010641, at z=7.1, has

estimates of the MBH mass MBH~2 x109 Msun (Mortlock et al. 2011)


For a BH accreting at a fraction fEdd of the Eddington limit, mass grows in time as:

M (t) =Min e(1−εεfEdd

t0.45Gyr

)

Under most conditions luminosity < Eddington limit:

LEdd = Mc2/tEdd


Mfin=2x109 Msun

tH(z=7)~0.75 Gyr

fEdd=0.3-1; ε~0.1

⇒ Min>300-ish Msun

ULASJ112010641

M (t) =Min e(1−εεfEdd

t0.45Gyr

)


HOW

can you make a

massive black hole ‘seed’?


Cosmological structure formation

They then break away from the global expansion, collapse down on themselves, and form a galaxy at the center

The universe after the Big Bang was not completely

uniform

Gravitational instability caused matter to condense until small regions become

gravitationally bound


Spherical collapse model Consider a flat, matter dominated universe (ok at early times) Imagine a spherical volume of the universe which is slightly denser than the background As the gravitational force inside a sphere depends only on the matter inside (Birkhoff ’s theorem) the overdense region behaves exactly like a small closed Universe!


z=20

z=10

z=5

z=2 z=1 z=0.5

z=0

The typical halo mass is an increasing function of time: bottom-up or hierarchical structure formation The mass functions of halos has a strong evolution with time


This is fine for collapsing dark matter... what about baryons? Gas needs to cool down in order to reach the density and temperatures required for star formation BEFORE the first generation of stars, the Universe is metal free (tautologic...): metal line cooling does not exist!

The atomic H cooling curve drops at temperatures below 104K Halos with Tvir< 104K have to rely on molecular hydrogen cooling


At high-z (z>20) most of the halos are small (Tvir< 104K) But only massive enough halos can cool, even with the aid of H2

Only a small fraction of halos at early times - the most massive ones - can host cold gas and eventually star forming clouds

No cooling

Tvir=104K

Tvir=103K

3-σ peaks


Tegmark et al.

Text

Baryons: need to cool => possible only in the most massive halos >106-108 Msun, i.e. the rarest at these highest redshifts

M. Kuehlen

Hierarchical Galaxy Formation small scales collapse first


HOW

can you make a (super)

massive black hole? from Rees 1984


HOW can you make the first

massive black holes? PopIII stars remnants

Gas-dynamical collapse

Stellar-dynamical collapse


PopIII stars remnants

✔Some simulations suggest that the first stars are massive M∼100-600 Msun (e.g., Abel et al. 2002; Bromm et al. 2003)

✔Metal free dying stars with M>260Msun leave remnant BHs with Mseed≥100Msun (Fryer, Woosley & Heger 2003)


Heger et al. M. Volonteri, Brera 2013

Problem: are the first stars massive enough?

M*>260 Msun è MBH>150 Msun

M*~30-150 Msunè MBH<<100 Msun

If BH mass too small difficult to settle down into galaxy

center => dynamics suppresses accretion/growth

opportunities

Recent simulations revise the initial estimates of the stellar

masses to possibly much lower values, just a few tens Msun


Gas-dynamical collapse (e.g. Bromm & Loeb 2003, Begelman, MV & Rees 2006)

✔Deep potential well for gas infall and collapse

✔Global dynamical instabilities to trigger inflow and dissipate angular momentum

✔Inflow and formation of a supermassive star that collapses into a MBH


Gas-dynamical collapse (e.g. Bromm & Loeb 2003, Begelman, MV & Rees 2006)

Direct contraction of a gas cloud into a BH encounters a

couple of problems: 1. ANGULAR MOMENTUM TRANSPORT Because of its angular momentum, collapsing gas clouds become rotationally supported at 106-8 Schwarzschild radii. 2. STAR FORMATION Instead of going into BH formation, the gas can fragment and form stars


1. ANGULAR MOMENTUM TRANSPORT BH formation: gravitational binding energy ∼ total energy

Angular momentum can halt collapse when the rotational support equals the gravitational binding energy There must be VERY efficient outward transport of J


BH formation in bar-unstable discs •  Systems with runaway global dynamical instability: BARS-

WITHIN-BARS

•  Self-gravitating gas clouds become bar-unstable when the level of rotational support surpasses a certain threshold

•  A bar can transport angular momentum outward on a dynamical timescale via gravitational and hydrodynamical torques, allowing the gas to shrink.

•  Provided that the gas is able to cool, this shrinkage leads to even greater instability, on shorter timescales, and the process cascades


2. STAR FORMATION Instead of going into BH formation, the collapsing gas can fragment and form stars BAD3:

✔ competition in gas consumption (i.e. part of the gas goes into stars instead of into BH formation ✔ collisionless stars do not dissipate angular momentum efficiently ✔ SNe can blow away the gas reservoir

NO H2/LOW METALLICITY/TURBULENCE HELP AVOID FRAGMENTATION M. Volonteri,

Brera 2013

The absence of H2 molecules from protogalactic halo gas can be justified by an intense dissociating UV radiation


Gas-dynamical processes Need high inflow rates ~ 1 Msun/yr (Begelman 2010)

èhighly unstable systems, eg merger driven gas collapse (Mayer et al 2010, MV & Begelman 2010)

•  If Mdot >1 Msunyr-1 formation of a supermassive star ~106 Msun. Potential too deep for nuclear ignition to halt contraction

•  When core temperature ~5x108K rapid cooling by thermal neutrinos è core collapse, formation of a ~10 Msun BH


Gas-dynamical processes •  When core temperature ~5x108K rapid cooling by thermal

neutrinos è core collapse, formation of a ~10 Msun BH

•  Max BH accretion rate is MdotEdd for the mass of the ENVELOPE

BHMM >*

)(~ *BHE

BHMax MM

MMM

!!"

#$$%

&


The BH can grow in mass until it swallows 1-10% of the “quasistellar” envelope, reaching masses ~104-105 Msun

Stellar-dynamical processes

Local dynamical instabilities can lead to mass infall instead of fragmentation and global star formation

✔ Inflow ⇒ within an inner, compact, region stars form abundantly ⇒ very dense cluster

✔mass segregation: massive stars sink to the center

✔ stellar collisions form a very massive star

Devecchi & MV 2009


Stellar-dynamical processes

VERY LOW, but NON-ZERO METALLICITY

✔ Inefficient fragmentation unless very high density: n > ncrit,Z ✔ In a dense star cluster the time for massive stars to segregate and merge into a massive star << tMS : to avoid mass loss in SN, and formation of compact objects (smaller cross section) ✔ at large metallicity stellar winds cause mass-loss. The supermassive star collapses into a low-mass BH; at low metallicity mass loss is negligible: MBH seed!

Devecchi & MV 2009 M. Volonteri, Brera 2013

Stellar dynamical channel

Fraction of halos forming a MBH seed

PopIII

dynamical channel

Mass function of MBHs formed via stellar dynamics






massive black holes?

M~100 Msun, high

efficiency

M~103 Msun, intermediate

efficiency

M~105 Msun, low efficiency


Testing MBH seed formation: ��two techniques

1.  Semi-analyical modelling -  Analytical “recipes” for MBH formation and growth -  Monte-Carlo realizations of the merger history of

dark matter halos in a LCDM cosmology -  computationally inexpensive =>statistical samples

2.  Cosmological simulations -  No need to use global quantities or smooth functions -  Gravity and hydrodynamics naturally included -  Either high resolution or large volume due to

computational costs

MV, Haardt & Madau 2003,MV & Natarajan 2009, MV & Begelman 2010


Galaxies

Massive Black Holes

mass:109-1012 solar masses

Rbulge∼GMbulge/σ2 KILOPARSEC

Rhalo∼GMhalo/σ2 MEGAPARSEC

Rbondi∼GMBH/cs2

Rinf∼GMBH/σ2

PARSEC

PARSEC

mass:105-109 solar masses

Rsch=2GMBH/c2 MICROPARSEC M. Volonteri, Brera 2013



✔High gas density ✔Zero or low-metallicity to avoid fragmentation



massive black holes?


Simulations of MBH seed formation

•  GASOLINE SPH N-body code (Wadsley et al. 2004)

•  Star formation, supernova feedback, metal diffusion, metal line cooling

•  New additions: •  Seed BH formation •  MBH mergers •  MBH accretion •  MBH feedback

Bellovary, MV et al. 2011


Seed MBH Prescription

•  Forming Seed MBHs •  Form seed black holes out of cold, dense,

zero-metallicity gas (n>102 cm-3, T<104 K) •  Probability of forming a black hole

(“efficiency”) •  Seed mass same as gas particle (104 - 106 M8)

Local prescription – driven by gas physics


Testing MBH seed formation •  High resolution “zoomed-in” cosmological simulations. We can accurately model the environment of BH formation and evolution

•  Three galaxies to z=5

• Four values of BH formation efficiency (0.05, 0.1, 0.3, 0.5)

hz1

h258

h603


Testing MBH seed formation hz1 at z = 5: M = 6 x 1011 M8

at z = 0: Massive elliptical h258 at z = 5: M = 3 x 1010 M8

at z = 0: Milky Way mass h603 At z = 5: M = 8 x 109 M8

at z = 0: Low-mass disk galaxy


MBH seeds form early

hz1 h258 h603

Bellovary, MV et al. 2011 Efficiency = 0.1

Black holes form earlier in more biased halos Different efficiencies just change how many MBHs form


MBH seeds form early

h258 eff = 0.1 z = 5

MBH formation is truncated due to contamination by

heavy elements, while stars continue forming


Halo Mass at time of MBH formation

Eff = 0.1

M~108 Msun << than assumed in cosmological simulations (1010 Msun) => implications for AGN feedback on the first galaxies


What is the smallest halo ��hosting a MBH?

50 % MBH fraction at the end of MBH formation epoch (z~5)


1. (Massive) black holes, AGN and quasars - difference between stellar and supermassive black holes - active vs quiescent BHs, including the Milky Way case

2. Massive black holes and galaxies - measurement of BH masses - local samples and correlations

3. Massive Black Hole formation - high-z quasars - seed BHs

4. Cosmic evolution - accretion vs mergers - Soltan's argument - BH-host vs z - triggering of AGN activity - role of feedback

HOW

can we find signatures of

massive black hole ‘seeds’?


The growth of MBHs in galaxies

Galaxy

Massive black hole

Early universe

Today

How do MBH seeds grow to become supermassive?

The seeds at high redshift are small, ∼100-105 Msun


MBHS are grown from

seed BHs. These seeds

are incorporated into

larger and larger halos,

accreting gas and

coalescing after galaxy

mergers.

time

local galaxy

high-z protogalaxies

local galaxy

high-z protogalaxies

Cosmic evolution of MBHs


How do MBH seeds grow to become supermassive? BH-BH mergers vs gas accretion

The seeds at z>20 are small, ∼100-105 Msun

Total mass density in MBHs is constant in time: just reshuffle

the mass function

Total mass density in MBHs grows with time


Soltan (1982) first proposed that the mass in black holes today is simply related to the AGN population integrated over luminosity and redshift

•  Mergers: total mass density in MBHs is constant in time: just reshuffle the mass function

•  Accretion: addition of gas - total mass density in MBHs grows with time



Soltan’s argument: integral over the LF of quasars

A fraction ε of mass goes into radiation Only a fraction (1-ε) goes into the BH Luminosity=energy per unit time


Soltan’s argument: integral over the LF of quasars

Luminosity function of quasars/AGN Total energy density emitted by accreting MBHs Luminosity=energy per unit time



mass density increases by > one order of magnitude in the last ~10 Gyr: accretion leads

Mergers: total mass density in MBHs is constant in time: just reshuffle the distribution of masses Accretion: adds external matter => total mass density in MBHs grows with time


Hopkins et al. 2007


PopIII remnants

Soltan’s argument: measures mass accreted by AGN Not all MBHs are AGN: the total mass density may be higher, it’s just that most MBHs are quiescent

Cosmic evolution of MBHs: integrated properties

Volonteri 2010

Soltan’s argument: integral constraints

u =

Z +1

0dz

Z +1

0dL�(L, z)L

��dt

dz

�� = 1.3⇥ 10�15 erg cm�3

integrated comoving energy density from quasars (Sołtan 1982)

with efficiency ε, the expected “relic” mass density density is

Local mass density is ~ 3.5-5.5×105 M⊙ pc-3 a factor 1.6-2.5 larger.

... AGN are not only unobscured, blue quasars!

... ρBH depends strongly on efficiency ε

⇥u =(1� ⇤)u

�c2= 2.2⇥ 105 M�Mpc�3 with ⇤ = 0.1

No correction for “obscured” AGNs ... when taken into account:Marconi +04: ρAGN ≃ 3.5 ×105 M⊙ Mpc-3 (ε≃0.1; hard X LF, Ueda +03) Shankar +08: ρAGN ≃ 4.5 ×105 M⊙ Mpc-3 (ε≃0.07; hard X LF, Ueda +03)

courtesy of A. Marconi

Cavaliere et al. (1973); Small & Blandford (1992); Merloni+ (2004; 2008; 2010)

Continuity equation for MBH growth��(a refined Soltan’s argument)

Need to know simultaneously mass function Ψ(M,t0) and accretion rate distribution F(dM/dt,M,t) [“Fueling function”]

Courtesy of A. Merloni

Mass function evolution: models

Kelly & Merloni 2012 Courtesy of A. Merloni

MBH- host relations: co- evolution of MBHs and galaxies

early universe

today today

adjustment

symbiosis

dominance


MBH- host relations: how are they established?

Is the correlation regulated by the galaxy or by the MBH? Feedback: The MBH regulates the process: when it reaches a limiting mass and luminosity it drives outflows that sweep away the surrounding gas, thus halting both its own growth and star formation in the galaxy. Feeding: the galaxy sets the MBH mass by regulating the amount of gas that trickles to the MBH Casuality: central-limit-theorem, i.e., a large number of mergers will average out the extreme values of MBH/Mbulge towards the ensemble average


MBH- host relations: when are they

established?

z=6

z=6 QSOs: very overmassive?

Wang et al. 2010

z~2-3 AGN & QSOs: galaxy lags the MBH growth -

dominance

Alexander et al. 2007

Merloni 2010


MBH- host relations: when are they established?

If self-regulation was different in the past, and

MBHs could grow relatively more w.r.t. their hosts,

either feeding or feedback must have been different

somehow


Mullaney et al. 2012

“The ensemble growth rate of SMBHs increases with both increasing M∗ and redshift in a remarkably similar manner to the average levels of star-formation taking place in star forming galaxies.”

Black Hole Accretion Rate vs Star Formation Rate

z ∼ 1 (open circles) z ∼ 2 (filled squares)


Black Hole growth traces galaxy’s growth

Statistically, MBHs seems to be in symbiosis with their galaxies M. Volonteri, Brera 2013

Zheng et al. 2010

Black Hole Accretion Rate vs Star Formation Rate

While the connection between BHAR and SFR seems to work statistically, there are issues in the link with the MBH-host correlations at high-z If BHAR=10-3 SFR always => BH mass =10-3 Mstar always - why do we see evidence for BH mass >10-3 Mstar at high-z? Observational bias or real?


Observational bias? • Current large-shallow surveys select only the most luminous quasars => the most massive holes at the highest redshifts

• What does the M-σ look like if we “cut” MBHs at ~1048 erg/s?

z=6 Volonteri & Stark 2011

z=6 Wang et al. 2010

Two not new biases

Bias1: if local MBHs included in M-sigma samples only if sphere of influence is resolved, slope flattens because points have been removed from systematically smaller masses and velocity dispersions

(Gultekin et al. 2009)


Two not new biases

Bias 2: scatter implies that the most massive MBHs are often hosted by modest galaxies that a priori would not be expected to harbor MBHs of high mass (Lauer et al. 2007) “Modest” galaxies are more common than “giant” galaxies, increasing the probability of detecting a large MBH in a modest galaxy.


Current large-shallow surveys: -  scatter hides

relationships -  flux limit + scatter

make for shallower slope of M-σ

Are MBHs really overmassive at high z?

z=6 γ=1.17

γtrue=0


Real differences? In fact for some high-z QSOs we can measure BHAR and SFR: most have BHAR>> 10-3 SFR

LSF vs. LAGN for 9 Herschel-detected sources at z=4.8 with measured MBH (red), the mean of 26 Herschel-undetected sources with measured MBH (black), and 68 low redshift sources. The curves are adopted from Rosario et al. 2012. The bottom black curve represents z<0.5 sources and the upper curve sources in the redshift range 1.5--2.5.

Netzer et al. 2013 M. Volonteri, Brera 2013

Real differences?

Willott et al. 2013 M. Volonteri, Brera 2013

Luminosity trend? Redshift trend?

At low redshifts, a strong change in the mean trend exists as a function of LAGN, which disappears at high redshifts.

Rosario et al. 2012

“At low AGN luminosities, accretion and SFR are uncorrelated at all redshifts. At high AGN luminosities, a significant correlation is observed between LSFR and LAGN, but only among AGNs at low and moderate redshifts (z < 1). “


Timescales?

Netzer 2009

One important caveat is the timescale over which we observe AGN and their hosts in a specific phase


MBH- host relations: redshift evolution

early universe

today today

adjustment

symbiosis

dominance




•  At high redshift the detection of the host galaxies is very difficult especially in luminous quasars: the AGN light swamps the galaxy light

•  At high redshift the estimate of the MBH mass is also more difficult as one has to rely on “virial masses” through different line widths in different redshift windows – not all lines equally good at tracing BH mass



•  At high redshift the detection of the host galaxies is very difficult especially in luminous quasars: the AGN light swamps the galaxy light

•  Also need to convert luminosity into mass – stellar population models

•  Is it really bulge mass, or total stellar mass?

•  At high redshift the estimate of the MBH mass is also more difficult as one has to rely on “virial masses” through different line widths in different redshift windows – not all lines equally good at tracing BH mass

MBH- bulge relation: redshift evolution


•  MBH- bulge luminosity: seems redshift independent (Peng et al 2006 – lensed galaxies; Decarli et al 2010; McLure et al. 2006. Note: hosts are classified as ellipticals in these samples.)

•  Once bulge luminosity is converted in bulge mass assuming passive stellar evolution: MBHs are “overmassive” at fixed galaxy mass

•  R=[MBH(z)/Mbulge(z)]/[MBH(z)/Mbulge(z)]~2 at z<2 •  R=~3-6 at z~2 •  R=~7 at z~3

MBH- stellar mass relation: redshift evolution


•  There is no real effort to determine the relationship at z=0 using the same techniques used at high-z for the current sample of galaxies with measured MBH mass!!!

•  Measure stellar mass via LIR (Cisternas et al.) or galaxy SED fitting (Merloni et al.): the latter is more accurate

•  Cisternas: R=0 at z~2 (stellar mass is reassembled in bulges by z=0)

•  Merloni: R ~(1+z)0.68

MBH- stellar mass relation: redshift evolution


MBH- host relations: highest redshift


•  Host galaxy cannot be imaged – use radio maps of CO that traces cold gas => gas masses and dynamical masses from line widths and beam size, plus “velocity dispersion” also from line width. Careful in comparing apples to apples!

•  MBH~10-30% Mgas Wang et al. 2010

MBH masses

MBH- host relations: highest redshift


•  Host galaxy cannot be imaged – use radio maps of CO that traces cold gas => gas masses and dynamical masses from line widths and beam size, plus “velocity dispersion” also from line width. Careful in comparing apples to apples!

•  MBH much overmassive at fixed σ Wang et al. 2010

z=6 Wang et al. 2010

MBH- host relations: sub-mm galaxies


•  Galaxies selected in sub-mm as very highly star forming systems: Ultra Luminous InfraRed Galaxies ~1000 Msun/yr SFR

•  MBH undermassive at fixed stellar mass

Wang et al. 2010 Alexander et al. 2007

MBH- host relations: summary


Wang et al. 2010 Alexander et al. 2007

4

4 5 6

Local Value QSOs

SMGs

Merloni et al.

Quasars at z~6 (Walter+09, Wang+2010)

Decarli+09

Courtesy of A. Marconi

Massive Black Holes and their host galaxies

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