What Can Transients Reveal about Massive Black Hole Assembly

1
What Can Transients Reveal about Massive Black
Hole Assembly?

• Milos Milosavljevic
• California Institute of Technology and Hubble
  Fellowship
• collaborators
• Andrew MacFadyen (IAS)
• Sterl Phinney (Caltech)

2
Open Problems

• The formation of Mbh it regulated by feedback, or else (why) do they
  fall on the Mbh - ? relation defined by dead
  quasars?
• How large were the seed progenitors of
  supermassive black holes?
• What is the role of coalescence and accretion
  from ISM and stellar tidal debris?
• How can binary massive black holes and
  coalescence be detected in surveys? talks by
  Komossa, Rodriguez

3
Why Transients?

• Spatial resolution (optical, VLBI) is limited,
  and we may have reached the limit excluding space
  interferometry.
• An unbiased census of low-luminosity AGN is
  difficult normal AGN are variable and diverse.
  Additional constraints may be available in the
  time domain.
• Key events (e.g., formation and early growth) are
  expected to be accompanied by starbursts.
  Transients can help resolve accreting black holes
  from starbursts.
• LSST and other new observatories make a
  systematic study of transients possible.

4
Strategy

• To design survey strategies that target multiple
  signatures (H?, X-rays) to maximize S/N.
• To identify the most robust (long lived)
  electromagnetic signatures associated with key
  events in the assembly of massive black holes.
• Binary massive black holes two step procedure
• Understand the structure of accretion flows in
  binary massive black holes.
• Understand the resulting emission and calculate
  ?F?(?,t).

5
galaxy merger
the bottleneck
log(decay timescale)
binary forms
coalescence
log(decay radius)
(Begelman, Blandford, Rees 1980)
6
galaxy merger
the bottleneck
log(decay timescale)
binary forms
coalescence
log(decay radius)
(Begelman, Blandford, Rees 1980)
7
Bogdanovic et al. 2006 PSU ? UMD
8
galaxy merger
the bottleneck
log(decay timescale)
binary forms
coalescence
log(decay radius)
(Begelman, Blandford, Rees 1980)
9
GG Tau
Duchene, McCabe, Ghez Macintosh 2004, w/Keck at
3.8 ?m
GG Tau Potter/Hawaii/Gemini/AURA/NSF
10
Gas around Binary Black Holes Alignment(variant
Bardeen-Petterson effect)
Less Precession
More Precession
Gas Orbits
Gas Orbits
11
MacFadyen MM 2006
initial surface density profile
surface density after tvisc
black hole orbits at this radius
12
(No Transcript)
13
MacFadyen MM 2006
disk eccentricity
disk ellipticity
14
(No Transcript)
15
central low-density hole
MacFadyen MM 2006
Total torque within radius r
Torque density
16
(No Transcript)
17
MacFadyen MM 2006
18
Guenther, Schaefer, Kley 2004
MacFadyen MM 2006
19
LSST
20
Sillanpää et al. 1996
21
galaxy merger
the bottleneck
log(decay timescale)
binary forms
coalescence
log(decay radius)
(Begelman, Blandford, Rees 1980)
22
The Final Year
MM Phinney 2005
23
The Final Year
MM Phinney 2005
24
The Final Year
MM Phinney 2005
25
Coalescence Transients
Penna, MM, Phinney, in prep.
26
Spectral Evolution
MM Phinney 2004
after
before
Thermal accretion disk spectra before and after
decoupling and coalescence. Thermal X-ray
emission is absent before coalescence.
27
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
• Hubble diagram ? geometry of the universe ? dark
  energy

Hughes 2002 Holz Hughes 2005 Kocsis, Frei,
Haiman, Menou 2006 Dalal, Holz, Hughes, Jain
2006 Dotti, Salvaterra, Sesana, Colpi, Haardt 2006
Holz Hughes 2005
28
Fine Points

• Too much supply ? circumbinary disk thick at the
  inner edge ? outflow.
• Misaligned black hole spin ? precession of the
  binary plane ? kicked material may miss the inner
  edge if disk is thin
• Unequal binary ? small black hole receives more
  mass ? mass equilibration.
• Excitation of binary eccentricity (Papaloizou,
  Nelson, Masset 2001 Armitage Natarajan 2005).
• GR introduces additional frequencies.
• Counter-rotating disk ? rapid cross-gap accretion.

29
Conclusions

• Transients are a key window to the assembly of
  petite massive black holes.
• Two-step strategy structure of the accretion
  flow structure of emission spectrum.
• Must find the most robust (most probable)
  transients.
• Circumbinary disk has a central hole.
• Accretion onto the black holes is reduced
  relative to the nominal viscous accretion rate.
• Circumbinary disk is eccentric cross-hole
  accretion is quasi-periodic and punctuated by
  outbursts.
• A year prior to coalescence, binary and disk
  decouple.
• After coalescence, the central hole fills in,
  thereby activating high-energy thermal emission.
• A combination of electromagnetic and
  gravitational-wave detection can be used to
  construct a Hubble diagram.