How does the Kerr parameter change as a Kerr black hole evaporates?

[snorkack]

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?

 

[PeterDonis]

the Kerr parameter

What do you mean by the Kerr parameter?

 

[snorkack]

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?

 

[PAllen]

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.