Kerr & Nordström Black Hole Evaporation: Q&A

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Discussion Overview

The discussion revolves around the evaporation of Kerr and Nordström black holes, focusing on the behavior of the Kerr parameter during evaporation and the implications of Nordström black holes in different environments, particularly regarding charge and current leakage in vacuum conditions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants inquire whether the Kerr parameter will remain constant, approach zero, approach unity, or settle at a value between zero and unity during the evaporation of a Kerr black hole.
  • There is a question regarding the behavior of Nordström black holes in a vacuum, specifically about the strength of the leak current and the conditions under which a Nordström black hole would evaporate at a constant charge-to-mass ratio.
  • One participant provides a definition of the Kerr parameter as the ratio of angular momentum to mass squared, noting its bounds between zero and unity, and questions how it evolves with Hawking radiation.
  • Another participant references existing literature on Hawking evaporation of Kerr black holes, suggesting that there are published papers that could provide more information.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the behavior of the Kerr parameter and the specifics of Nordström black holes, indicating that multiple competing views and questions remain unresolved.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the Kerr parameter and the mathematical dependencies of Nordström black holes, which are not fully explored or resolved.

Who May Find This Useful

This discussion may be of interest to those studying black hole thermodynamics, quantum mechanics in strong fields, and the theoretical aspects of black hole evaporation.

snorkack
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When a Kerr black hole evaporates, what will the Kerr parameter do?
Stay constant at initial value?
Approach zero?
Approach unity?
Approach a target value somewhere between zero and unity?

Also, Nordström black holes in practice (with matter around) would have a strong tendency to attract charged plasma. But in perfect vacuum? How strong would the leak current out of a Nordström black hole be? Quantum mechanics suggests a tail of tunnelling in strong electric fields. At which charge would a Nordström black hole be evaporating at constant q/m, if the dependence of q on m is that simple? And does the mathematics of Nordström black hole expressly depend on electron rest mass?
 
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snorkack said:
the Kerr parameter
What do you mean by the Kerr parameter?
 
PeterDonis said:
What do you mean by the Kerr parameter?
The expression
Jc/GM2
where J is angular momentum, c speed of light, G gravitational constant and M the mass of the hole.
It is bound to be between zero (it is Schwarzschild hole) and unity for any black hole.
How does it evolve on Hawking radiation?
 
If you search "Hawking evaporation Kerr BH" you find a good number of reputably published papers discussing this. At the moment, I don't have time to quick read them to try to choose the most informative.
 

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