Properties of the instantaneous ergo surface of a Kerr black hole

  title={Properties of the instantaneous ergo surface of a Kerr black hole},
  author={Nicos Pelavas and Nicholas Neary and Kayll Lake},
  journal={Classical and Quantum Gravity},
This paper explores properties of the instantaneous ergo surface of a Kerr black hole. The surface area is evaluated in closed form. In terms of the mass (m) and angular velocity (a), to second order in a, the area of the ergo surface is given by 16πm 2 +4 πa 2 (compared to the familiar 16πm 2 − 4πa 2 for the event horizon). Whereas the total curvature of the instantaneous event horizon is 4π , on the ergo surface it ranges from 4π (for a = 0) to 0 (for a = m) due to conical singularities on… 

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