|講演タイトル||Vacuum energy and apparent horizon|
Effects of the negative vacuum energy plays a crucial role in a small neighborhood of the apparent horizon of evaporating black holes. We consider spherically symmetric configurations in which the collapsing star has already collapsed below the Schwarzschild radius. For static case, there are no divergences around the Schwarzschild radius even in the Boulware vacuum, if the back reaction from the negative vacuum energy is taken into account. The geometry around the Schwarzschild radius is modified by the effect of vacuum energy and has no event horizon. Instead, there is a local minimum in the radius, like the geometry around the neck of the wormhole. The local minimum of the radius becomes the apparent horizon when the black hole is evaporating by the Hawking radiation. Information can get away from the apparent horizon since it is time-like because of the negative vacuum energy.