Comment on ``Strength and genericity of singularities in Tolman-Bondi-de Sitter collapse'' and a note on central singularities

TL;DR

This paper corrects a previous claim about the existence of certain geodesics in Tolman-Bondi-de Sitter collapse, showing that the absence of radial null geodesics indicates the singularity is censored in spherical symmetry.

Contribution

It clarifies the conditions under which central singularities are censored, correcting prior assertions about geodesic emergence in these collapse models.

Findings

Radial null geodesics do not emerge from certain singularities.

Absence of radial null geodesics implies singularity censorship.

Corrects previous misconceptions in the literature.

Abstract

It has been claimed that the Lemaitre-Tolman-Bondi-de Sitter solution always admits future-pointing radial time-like geodesics emerging from the shell-focussing singularity, regardless of the nature of the (regular) initial data. This is despite the fact that some data rule out the emergence of future pointing radial null geodesics. We correct this claim and show that in general in spherical symmetry, the absence of radial null geodesics emerging from a central singularity is sufficient to prove that the singularity is censored.