2003

Birth and Dynamics of Galactic Black Holes

• Demography of quiescent black holes in the present-day universe

• Demography of accreting black holes (quasars) at early cosmic times

• Dynamics of black holes in galactic centers: Brownian motion, binaries

• Effects of quasars on their cosmic habitat

Collaborators: Rennan Barkana, Volker Bromm, Pinaki Chatterjee, . . Lars Hernquist, Stuart Wyithe

The Black Hole in the Galactic Center: SgrA*

VLT with Adaptive Optics

•“3-color”: 1.5 - 3 um

• 8.2 m VLT telescope

• CONICA (IR camera)

• NAOS (adaptive optics)

• 60 mas resolution

Stellar Positions & Motions

Reid et al. 2002

SgrA* in July 1995

Where was Sgr A* in May‘02?

• Sgr A* position: 10 mas

• Star “S2”

seen at pericenter

V ~ 5000 km/s !

Orbit determined

S2’s orbit

• 15 year period

• e = 0.87

• Pericenter

15 mas = 120 AU . = 17 light-hours

(Schoedel et al 2002)

Simultaneous fit of orbits implies:

1. BH mass:

2. BH proper motion: < 0.8+-0.7 mas/yr

(4æ0:3) â (d=8kpc)3 â 106M ì

Ghez et al. 2003

SO-16 closest approach at 90 AU

Feeding SgrA* with Stellar Winds

Loeb, astro-ph/0311512

J < J max = ñ c4GM ï

ð ñEmission region:Emission region:

Sgr A*’s motion

• Continues along Galactic Plane

• Remove Sun’s motion

V(Sgr A*) < 7 km/s

Reid et al. (2002)

Lower Limit on Sgr A*’s Mass

• Backer & Sramek (1999): MV2 ~ mv2 <energy>• Reid et al (1999): MV ~ mv <momentum>• Chatterjee, Hernquist & Loeb (2002)

mass estimator: <energy>

Mlim ~ G M(R) m / R V2

• V < 2 km/s M > 106 Msun

Apparent Deviations from Keplerian Orbits

Loeb 2003 (astro-ph/0309716)

dtobs = (1+ vk=c)dt

a? ;obs = dt2obs

d2x? = (1à c2vk)a? à c

v? ak

Doppler transformation of time:

BH

star

cv ø 10à 2 at ø 100A:U:

Probing the Spacetime Around SgrA* with Pulsars

• BH spin vector from frame-dragging + imaging of pulsar orbit• Inner stellar cluster from gravitational scattering events• Test accretion flow models by measuring plasma density

Pfahl & Loeb 2003 (astro-ph/0309744)

~10-100 massive stars with P<100 yr and lifetime of ~ 107 years~1000 NS in steady state 1-10 detectable pulsars at 10-20 GHz

Enclosed Mass

Schoedel et al. 2002

Water Masers: NGC 4258

Moran, Greenhill, & Herrnstein (2000)

Keplerian Velocity Profile

Miyoshi et al. 1995

Mass densities

Object Density Method

(Msun/pc3)

M 87 2 x 106 HST: 3x109 Msun in 7 pc

NGC 4258 7 x 109 VLBA : H2O 3x107 Msun in 0.1 pc

Sgr A* 8 x 1015 S16’s orbit 3x106 Msun in 90 AU

Sgr A* 2 x 1021 Sgr A*s p.m. 1x106 Msun in 1 AU

SMBH 5 x 1025 Rsch 3x106 Msun in 0.05 AU

Correlation between black hole mass and velocity dispersion of host stellar system

Tremaine et al. 2002

ì = 4:02æ0:32;ë = 8:13æ0:06

ì = 4:02æ0:32;ë = 8:13æ0:06

ë = 8:22æ0:07

ì = 4:58æ0:52

Ferrarese 2002

log(M=M ì ) = ë + ì log(û?=200km=s)

Quasars Reside in Galaxies

Archeology of the Universe

The more distant a source is, the more time it takes for its light to reach us. Hence the light must have been emitted when the universe was younger. By looking at distant sources we can trace the history of the universe.

distanceEarth

Quasars already exist at z~6, only a billion years after the big bang!

Becker et al. 2001

The Earliest Quasar Detected: z=6.43

Fan et al. 2002

Cosmological Infall Around Quasars at z>6

Barkana & Loeb, Nature, 2003

M BH = 108M ì

ð

300km=sVC

ñ5

Ly Line of Quasars

Quasar spectrumSDSS (Vanden Berk et al. 2001)HST (Telfer et al. 2002)ROSAT (Yuan et al. 1998)

Ferrarese et al. 2002Tremaine et al. 2002Wyithe & Loeb 2002

4:6â 108M ì

1:9â 109M ì

2:5â 1012M ì

4:0â 1012M ì

z = 4:80

z = 6:28

M BH =

M BH =

M =

M =

SDSS 1122à 0229

SDSS 1030+ 0524

SDSS 1122à 0229

SDSS 1030+ 0524

SDSS 1122à 0229

SDSS 1030+ 0524

Basic Facts About the Universe• On large scales our universe is simple:

HOMOGENEOUS HOMOGENEOUS: the same everywhere

ISOTROPIC: the same in all directions

Observer 1

Observer 2

Observer 3

Earth

Direction 2Direction1

Direction 3

But on small scales the universe is clumpy

Mean Density

Early times

Intermediate times

Late times

Formation of Massive Black Holes in the First Galaxies

Add Bromm

Low-spin systems: Eisenstein & Loeb 1995

Numerical simulations: Bromm & Loeb 2002

R < 1pc

M 1 ø 2:2â 106M ì

M 2 ø 3:1â 106M ì

õ = 0:05

H2 suppressed

Eddington Limit

For a spherical geometry, the outward radiation force balances the inward gravitational force at the Eddington luminosity:

Gravitational force per proton:

Radiation force per electron:

Accretion of fuel is possible only if

accretion

gasBH

GMmp=r2

(L=4ùr2c)ûT

L E = (4ùGMmpc=ûT) = 1:4â 1046(M=108M ì )erg=s

L < L E

Self-regulation of Supermassive Black Hole Growth

quasar

! 108M ì

M bh = 1:5 200km=sû

ð ñ5

Ltdyn ø 23M gasû2

dynamical time of galactic disk maxf Lg = L E / M bh

halo velocity dispersion

After translating û ! û? this relation matches the observed correlation in nearby galaxies (Tremaine et al. 2002; Ferarrese & Merritt 2002)

M à ûã

Silk &Rees 1998; Wyithe & Loeb 2003

Quasar Luminosity Function

Wyithe & Loeb 2002

Simple physical model:

*Each galaxy merger leads to a bright quasar phase during which the black hole grows to a mass and shines at the Eddington limit. The duration of this bright phase is proportional to the (smaller than unity) mass ratio in the merger.

*Merger rate: based on the extended Press-Schechter model in a LCDM cosmology.

duty cycle ~10 Myr

M ï / v5c

Did the most massive galaxies form at z>6,only a billion years after the Big-Bang?

Core of CDM halos stabilizes at z~6

Stars=collisionless fluid

Loeb & Peebles 2002

late accretion

Proposal confirmed by N-body simulations

Gao Liang & Simon White

(2003) Loeb & Peebles 2002

Brownian Motion of a Massive Black Hole in a Stellar System

Chatterjee, Hernquist, & Loeb 2001 (ApJ, PRL)

For a non-Maxwellian distribution function of stars the black hole is not in strict equipartition

Black Hole Binaries due to Galaxy Mergers

X-ray Image of a binary black hole system in NGC 6240

Komossa et al. 2002

z=0.025

10kpc

Dynamics of black hole binaries

Chatterjee, Hernquist, & Loeb 2002

Figure1.ps

Typical binaries coalesce in less than 10 Gyr due to wandering

Numerical experiment:

400,000 stars

M/M*=0.25%

R

Open issue: kick velocity

Laser Interferometer Space Antenna

Gravitational Wave Amplitude from a Black Hole Binary at z=1

Gravitational Radiation from Coalescence of Massive Black Hole Binaries

Wyithe & Loeb 2002

LISA

PULSARS

REDSHIFT FREQUENCY (Hz)

Environmental Effects of Quasars

Radiative: ionization of intergalactic hydrogen and helium

Hydrodynamic: powerful relativistic outflows

Spectrum of a High Redshift Quasar (z=5.73)

Djorgovski et al. 2001, ApJL, submitted

Transmitted flux ---> HI/HII<1e-6 (Fan et al. 2000)

Djorgovski et al. 2001

On the Threshold of the Reionization Epoch

Structure Formation in the IGM

Density contrast of gas shocked between z=0.14-0.09

Density contrast of gas at z=0 for a 100x100x10 Mpc^3 slice

Evolutionary Stages of Reionization

• Pre-overlap

• Overlap

• Post-overlap

neutral H

Ionized H

Reionization Histories of H, He

Free Parameters: (i) transition redshift, z_tran, above which the stellar IMF is dominated by massive, zero-metallicity stars; (ii) the product of the star formation efficiency and the escape fraction of ionizing photons in galaxies, .

Wyithe & Loeb 2002

H+

He+

He++

Quasar model fits luminosity function data up to z=6

ztran

f escf ?

FILLING FRACTION

REDSHIFT

Quasars as Perturbers:Impact of Quasar Outflows on the IGM

Furlanetto & Loeb 2001

Intergalactic Medium (IGM)

Is the IGM fully magnetized just like the ISM?

jetBAL outflow

quasar

small-scale structure; magnetization; ionization

Magnetized bubble

Volume Filling Factor of Quasar Bubbles

Magnetic energy density normalized by thermal at 10^4 K

Volume filling factor of IGM

Probability Distribution of Bubble Magnetic Field

*Could account for intra-cluster and galactic fields through adiabatic compression. Explains synchrotron halos of clusters.

B / ú2=3

Injection of Positrons from AGN Jets

Furlanetto& Loeb 2002

AGN

e+e- jet

Spectrum of Positron Annihilation Line3-photon decay of Positronium does not smear line due to keV temperature of cluster electrons (direct annihilation more probable)

Line signal detectable with INTEGRAL (launched Oct. 2002) and EXIST (space station) for rich X-ray clusters out to 100 Mpc

More details: ApJ, 572, 796 (2002)

What fraction of the earliest quasars is being gravitationally lensed?

Barkana & Loeb 2000

OCDM

LCDM

SCDM

- PS Halos

- -No evolution

Are the Highest-Redshift Quasars Gravitationally Lensed?

Wyithe & Loeb, Nature 2002

4 SDSS Quasars with z>5.73

QuasarObserver Lensing Galaxy

Excess magnification due to stars next to one of the images

Time Delay = (gravitational +geometric)

Magnifying the Broad Line Region of Quasars with Stellar Microlenses

Quasar accretion disk

(source of continuum emission)Wyithe & Loeb 2002

Observed Time-Delay Lightcurves

RX J0911+05

SBS 1520+530

Burud et al. 2002

Anomalies of Time-Delay Lightcurves

Observations: up to a few percent variations on tens to hundreds of days

Observed anomalies in RX J0911+05 & SBS 1520+530 by Burud et al. (2002) ---> N<10^6

Lack of anomalies in Q2237+0305 ---> N>10^4

Inferred cloud number is consistent with bloated star model (Alexander & Netzer 1997)

The Future of the Intergalactic MediumÒË = 0:7;Òm = 0:3

(Recombination time)>>(Hubble time) outside collapsed objects today. This inequality will get much stronger in the future because the IGM density will be diluted exponentially with cosmic time.

Future Evolution of Nearby Large-Scale Structure

Nagamine & Loeb 2002

Coma

Great Attractor Perseus

Pisces

The Long Term Future of Extragalactic Astronomy

Loeb 2002, PRD; astro-ph/0107568

us

c

Accelerating

source

AnalogyAnts = Photons Balloon=Expanding Space

AnalogyAnts = Photons Balloon=Expanding Space

visited area (horizon) since blowing started (Big Bang)

AnalogyAnts = Photons Balloon=Expanding Space

visited area (horizon) since the blowing began (Big Bang)

Ants can be separated at a rate much larger than their own walking speed

Maximum Visible Age

All sources above a redshift of 1.8 are already out of causal contact with us!

How many galaxes will reside within our event horizon in 100 billion years?

Answer: one

(the merger product of the Andromeda and Milky-Way galaxies)

Ejection of Stelar Mass Black Holes from Globular Clusters

star-star

star-BH

BH-BH ejection Chatterjee, Loeb & Haernquist 2003

Bright quasars reside in massive galaxies: Spectral Signature of Cosmological Infall Around the First Quasars

Barkana & Loeb, Nature, 2003; astro-ph/0209515

infallaccretion shock

virialized gas

observer

redshiftedaccretion shock

Simulation of Reionization

log(f_HI)

Ionizing - Background

log(gas density)

log TGnedin (2000)

z=11.5

z=7 z=4.9

For comprehensive reviews on Reionization, see: *Barkana & Loeb 2001, Physics Reports 349, 125*Loeb & Barkana 2001, ARA&A, 39 (Sep. 15)

1-sigma 2-sigma 3-sigma

Atomic cooling

H_2 cooling

2-sigma

Collapse Redshift of Halos

Probability Distribution of Bubble Radius

*Magnetic pressure larger minimum b-parameter of Lya forest

Redshift and Splitting Distributions of Lenses

- LCDM

- - OCDM

… SCDM

z_s=5

z_s=10

z_s=2

z_s=5 z_s=10

Flux from Lensing Galaxy in G-P Trough

z_s~6

I*=22.2

23.322.2

SDSS at z=6.28

Alternative Interpretations of Lightcurve Anomalies

Hot spots in accretion disk

Black Hole

(Gould & Miralda-Escude 1997)

Hotspots: timescales are too short compared to observations!

Second Alternative:Microlensing by Planets

Accretion disk

Motion in 10 years with a transverse velocity of 400 km/s

(Schild 1996)

Planets: timescales are too long!(Also, ruled out by the MACHO search).

ü/ ú2R2

/ (1+ z)4

Absorption Spectrum

Spectrum of a Source Just Beyond the Reionization Redshift

A Simple Explanation

Explain: binding enrgy per dynamical time

Laser Interferometer Space Antenna (LISA)

Future Prospects

• Vlim ~ 1/t3/2

• Mlim ~ 1/V2lim <energy>

~ t3

• When Vlim ~ 2 km/s (~2007),

Mlim ~ 106 Msun

• Could show ALL mass in Sgr A* !Reid 2002