Large gravitons and near-horizon diffeomorphisms

Understand

Usual gauge fixing procedures in classical general relativity rely on the existence of solutions of a second order wave equation.

• We propose to use the equation to relate asymptotic symmetries at infinity to asymptotic symmetries of a black hole horizon, in tune with recent proposals.
• We illustrate the construction for the BTZ and four-dimensional Kerr black holes.
• We find in both cases a realization of the group of diffeomorphisms of the circle $S^1$.