2 black holes, 2*M -> 1 b.h., 2*M - f*2*M?

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Discussion Overview

The discussion revolves around the energy loss during the merger of two equal-sized black holes, specifically focusing on the fraction of energy, denoted as f, that is lost as gravitational radiation. Participants explore theoretical limits, numerical simulations, and potential variations in energy loss as a function of black hole mass.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about the fraction of energy lost as gravitational radiation during the merger of two black holes of mass M.
  • Another participant references a paper that discusses gravitational waves from black-hole mergers, suggesting it as a starting point for understanding the topic.
  • A third participant mentions that for two identical static black holes, the theoretical upper limit for energy loss is the Hawking bound of (2-√2)m, which corresponds to about 29% of the initial total mass, while numerical simulations show lower values typically between 0.1% and 4%, with some cases reaching up to 14% in the scattering regime.
  • A later reply reiterates the reference to the same paper and notes that for star-sized black holes, the fraction lost is about 1/20 of the mass of the initial black hole pair, questioning how this fraction might change with varying black hole mass.

Areas of Agreement / Disagreement

Participants express differing views on the fraction of energy lost during black hole mergers, with some citing theoretical limits and others referring to numerical simulations. The discussion remains unresolved regarding how the fraction of energy loss varies with black hole mass.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the conditions of black hole mergers and the specific definitions of mass and energy loss. The varying results from theoretical and numerical approaches highlight the complexity of the topic.

Who May Find This Useful

This discussion may be of interest to those studying gravitational waves, black hole physics, and the dynamics of black hole mergers, particularly in the context of energy loss and its dependence on mass.

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2 black holes, 2*M --> 1 b.h., 2*M - f*2*M?

For equal sized black holes of mass M, what fraction, f, of the energy typically gets lost as gravitational radiation when roughly equal sized black holes merge?

If f were plotted verses mass would the function have a maximum?

Thanks for any help!
 
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For starting point, try page 4 of

http://arxiv.org/abs/0708.4202
Gravitational waves from black-hole mergers
John G. Baker, William D. Boggs, Joan M. Centrella, Bernard J. Kelly, Sean T. McWilliams, James R. van Meter
 


For two identical static black holes, the rigorous theoretical upper limit is the Hawking bound of (2-√2)m (eg 29% of the initial total mass). Numerical simulations typically show much lower amounts of radiation on the order of 0.1..4% (and up to 14% in the scattering regime).
 
Last edited:


atyy said:
For starting point, try page 4 of

http://arxiv.org/abs/0708.4202
Gravitational waves from black-hole mergers
John G. Baker, William D. Boggs, Joan M. Centrella, Bernard J. Kelly, Sean T. McWilliams, James R. van Meter

If I follow the paper above, for star sized black holes the fraction lost is about 1/20 the mass of the initial black hole pair. Are there any simple arguments one could give to explain how this fraction changes (or does not change) with black hole mass.

Thanks for your help!
 

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