We propose a hoop conjecture in the presence of a positive cosmological constant Λ: when an apparent horizon forms in a gravitational collapse, the matter must be sufficiently compactified such that the circumference scrC satisfies the condition scrC4πM4πMcrit, where M is the Abbott-Deser mass of the collapsed body and Mcrit=1/3 Λ. To confirm our conjecture, we investigate two cases: (1) initial data of a prolate or oblate dust spheroid, and (2) the Kastor-Traschen spacetime which describes a black hole collision with Λ. We also discuss a relation between the hoop conjecture and an appearance of a naked singularity.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)