Violation of weak cosmic censorship by the Oppenheimer–Snyder collapse
摘要
We consider the possibility that the weak cosmic censorship conjecture can be violated using the Oppenheimer–Snyder collapse model with a perfect fluid star interior. In the first strategy, we assumed a metric model with a naked singularity; in this case, the Oppenheimer–Snyder collapse was possible, and the null energy condition is also satisfied. However, this is just a toy model because there is no known solution to the Einstein equation. To avoid this problem, in the second strategy, we can consider a naked singularity solution as a proper solution of the Einstein equations; however, in this case, we need to introduce a thin shell on top of the perfect fluid star. In this case, gravitational collapse is allowed, but the null energy condition should be violated at the thin shell. In conclusion, we could not find a physically viable model that violates weak cosmic censorship; however, it opens a window for studying the properties of cosmic censorship constructively. The violation of weak cosmic censorship may be possible if a modified gravity model provides a solution that allows the Oppenheimer–Snyder collapse to occur without a shell. Additionally, regarding the thin-shell case, the shell approaches the naked singularity closely without violating the null energy condition, although it must eventually violate the null energy condition at the singularity; this might be regarded as an effective violation of cosmic censorship.