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Conformal invariance of black hole temperature. (English) Zbl 0794.53056

Summary: It is shown that the surface gravity and temperature of a stationary black hole are invariant under conformal transformations of the metric that are the identity at infinity. More precisely, we find a conformal invariant definition of the surface gravity of a conformal Killing horizon that agrees with the usual definition(s) for a true Killing horizon and is proportional to the temperature as defined by Hawking radiation. This result is reconciled with the intimate relation between the trace anomaly and the Hawking effect, despite the non-invariance of the trace anomaly under conformal transformations.

MSC:

53Z05 Applications of differential geometry to physics
83C57 Black holes
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