BH Demographics

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BH Demographics

• D. Richstone
• Univ of Michigan
• Thanks to key collaborators
• Tod Lauer,
• Sandy Faber,
• Karl Gebhardt,
• Scott Tremaine

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And thanks to NASA
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• Kormendy/Gebhardt review fig 2.

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L and ?4

• Implies L-M and s-M relations are not consistent
  at high mass.
• Can we guess which is correct?
• Measurements of BH M in BCGs would settle it.
  

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Core scouring (mass ejection by bh orbit decay)

• L predicts r? better than ? does.
• Under core-scouring, the relationship betweem Mbh
  r? is the fundamental one.
• M2 (2001) argue that Mej ?p ?2 r?. Can combine
  this with the empirical relationships above

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If core scouring is correct.

• The r-? relation predicts Mej Mbh2.9.
• The r-L relation predicts Mej Mbh1.1.
• The r-? relation predicts therefore that the most
  massive cores are formed by souring with
  relatively low mass bh. Seems implausible.
• The M2 simulations show Mej Mbh.

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Compare inferred demographics to quasars.

• Dispersion-based demographics predict fewer high
  mass bh than one infers from the quasar
  luminosity functions.
• This is especially true when the latter are
  interpreted with a physical model for the
  lifetime above any given L/Leddington.

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Conclusions.

• There is a conflict between the predicted
  densities of the highest mass BH according to
  whether one uses dispersion- or luminosity-based
  predictors of the BH mass in galaxies.
• One can make 3 weak arguments that L is the
  better predictor
• L is a better predictor (less scatter) of the
  core (break) radius.
• Under core scattering, dispersion leads one to 2
  implausible conclusions.
• L-based BH densities are consistent with a
  physical interpretation of quasar counts.
  Dispersion-based ones are probably not.
• Measurements of BH mass in BCGs should settle the
  issue. Stay tuned.