Entropy from near-horizon geometries of Killing horizons

Understand

We derive black hole entropy based on the near-horizon symmetries of black hole space-times.

• To derive these symmetries we make use of an $(R,T)$-plane close to a Killing horizon.
• We identify a set of vector fields that preserves this plane and forms a Witt algebra.
• The corresponding algebra of Hamiltonians is shown to have a non-trivial central extension.