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Entropy of the isolated horizon from the surface term of gravitational action. (English) Zbl 1304.83019

Summary: Starting from the surface term of gravitational action, one can construct a Virasoro algebra with central extension, with which the horizon entropy can be derived using the Cardy formula. This approach provides a new routine for calculating and interpreting the horizon entropy. In this paper, we generalize this approach to a more general case, the isolated horizon, which contains non-stationary spacetimes beyond stationary ones. By imposing appropriate boundary conditions near the horizon, the full set of diffeomorphisms is restricted to a subset where the corresponding Noether charges form a Virasoro algebra with central extension. Then by using the Cardy formula, we can derive the entropy of the isolated horizon.

MSC:

83C35 Gravitational waves
83C57 Black holes
83C75 Space-time singularities, cosmic censorship, etc.
94A17 Measures of information, entropy
83C05 Einstein’s equations (general structure, canonical formalism, Cauchy problems)
83C40 Gravitational energy and conservation laws; groups of motions
17B68 Virasoro and related algebras
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