Outer Trapped Surfaces in Vaidya Spacetimes

TL;DR

This paper proves that in Vaidya spacetimes with bounded mass, the outer boundary of outer trapped surfaces coincides with the event horizon, but trapped surfaces may not always reach the horizon.

Contribution

It establishes a precise relationship between trapped surfaces and the event horizon in Vaidya spacetimes, clarifying their spatial extent.

Findings

Outer boundary of outer trapped surfaces is the event horizon.

Trapped surfaces may not extend to the event horizon.

Results apply to Vaidya spacetimes with bounded total mass.

Abstract

It is proven that in Vaidya spacetimes of bounded total mass, the outer boundary, in spacetime, of the region containing outer trapped surfaces, is the event horizon. Further, it is shown that the region containing trapped surfaces in these spacetimes does not always extend to the event horizon.