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Black Hole Binaries

Milos MilosavljevicCalifornia Institute of Technology & Hubble Fellowship

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109108106105 107104103102101

solar masse

stellarbinaries

log cosmic density per log ma

quasars

Milky Way

unknown

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Stefan Gottloeber (AIP, Potsdam) & collaborators

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Owen, O’Dea, Inoue, Eilek, NRAO/AUI, Twin radio jets in Abell 400: two black holes in the same galaxy!

NASA/CXC/MPE/S. Komossa et al. Ultraluminous infrared galaxy NGC6240 contains two accreting black holes separated by 2 kpc.

Rodriguez, Taylor, Zavala, Peck et al. 2006 - see poster!!!

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Mergers Proceed on a Dynamical Time

N-body simulation: Milosavljevic & Merritt 2001

10-100 pc

“Hard” binary forms when black hole separation becomes smaller than the radius of dynamical influence, a < rbh

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position along a slit (arcsec)

rms velocity (km/s)

Joseph et al. 2001, HST/STISRMS stellar velocity at center of dwarf galaxy M32. Central rise σ~(GMbh/r)1/2 is a

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Gravitational Wave Emission

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Simulation: Frans Pretorius (U

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black hole mass (solar mass)

The Final Parsec “Problem”

binary’s semi-major axis (parsec)

GALAXY MERGER

COALESCENCE

diffu

sion Milk

y Way

cor

log(decay timescale)

log(decay radius)

galaxy merger

the bottleneck

coalescencebinary forms

Begelman, Blandford, Rees 1980

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Gravitational Slingshot Interaction

star

binary

U

V cos θ

V sin θ

V sin θ

2U + V cos θ

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The Loss Cone

diffusion

circular orbit

radial orbitMakino & Funato 2004

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Loss cone refilling by merger tides?Zhao, Haehnelt, Rees 2002

T

star

satellite

satellite’s orbital

satellite’s angular velocity

star’s angular velocity

rate at which 1-e changes by order unity

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Loss cone refilling in non-spherical potentialsMagorrian & Tremaine 1999, Yu 2002, Merritt & Poon 2004

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100 pc

HST/ACS VCS, Ferrarese et al

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Gas around Binary Black Holes: Alignment(variant Bardeen-Petterson effect)

Gas Orbits

More Precession

Less Precession

Gas Orbits

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Duchene, McCabe, Ghez & Macintosh 2004,w/Keck at 3.8 μm

GG Tau

GG Tau: Potter/Hawaii/Gemini/AURA/NSF

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Torque Balance and Disk Truncation

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ASC FLASHsimulation,MacFadyen & MM 2006 rbh

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The Final YearMM & Phinney 2005

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The Final YearMM & Phinney 2005

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The Final YearMM & Phinney 2005

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Spectral Evolution

after

before

Thermal accretion disk spectra before and after decoupling and coalescence. Thermal X-ray emission is absent before coalescence.

MM & Phinney 200

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Cosmology with Black Hole Mergers• Gravitational wave train

– luminosity distance but not redshift (redshift degenerate with mass).

– localization: arcminutes to degrees

– thousand host galaxy candidates!

• Monitoring in X-rays at high spatial resolution– afterglow– host galaxy identification,

redshift– “standard candle” (independent

distance and redshift)– confusion due to lensing

• Distance-redshift relation, cosmology

Hughes 2002, Holz & Hughes 2005Kocsis et al. 2006

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Future: MBH Assembly in the Time Domain

MacFadyen & MM, in prep. LSST

Guenther, Schaefer, Kley 2004

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Confusion: Tidal Disruptions!

S. Komossa

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NASA/CXC/SAO

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Stellar mass density as a function of distance from the center of the galaxy: cusps and cores (Gebhardt et al. 1996)

MM 2002, data: Rest et al./WFPC2

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Core Depletion

MM & Merritt 2001

The Mass DeficitDefinition: The mass that had to be removed to produce the observed, centrally-depleted density distribution from a featureless, “universal”profileThe Simulations Yield:

Mdeficit <~ 2 Mbinary(for equal-mass black holes)

Faber et al. 1997, MM et al. 2002

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MM et al. 2002

deficit

black hole masstheoretical prediction for single merger

Are multiple mergers requiredto explain large mass deficits?

Merritt 2006

number of merger generations

deficit

Graham 2004

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Conclusions• Black hole coalescence is expected in the merger

low-mass massive black holes (but radiation recoil and three-body ejections may complicate retention).

• Departures from sphericity lead to efficient loss-cone refilling. Merger tides do not last long enough.

• Accretion around black hole binaries and black hole coalescence will be accompanied by a variety of electromagnetic transients.

• Simultaneous detected of gravitational radiation andelectromagnetic emission will help measure distance-redshift relation.

• Galaxy cores are plausible relics of black holemergers.

• Understanding of the population of low-mass massive black holes a top scientific priority.