Regularising the JNW and JMN naked singularities

TL;DR

This paper extends a regularisation method to naked singularity spacetimes, creating wormholes or preserving singularities, and investigates their properties, particle motion, and stability through quasinormal modes.

Contribution

It introduces a novel application of the Simpson-Visser regularisation to JNW and JMN spacetimes, revealing new geometric features and stability characteristics.

Findings

Modified JNW can be a traversable wormhole or naked singularity.

Modified JMN always results in a wormhole.

The geometries exhibit unique particle motion and stability properties.

Abstract

We extend the method of Simpson and Visser (SV) of regularising a black hole spacetime, to cases where the initial metric represents a globally naked singularity. We choose two particular geometries, the Janis-Newman-Winicour (JNW) metric representing the solution of an Einstein-scalar field system, and the Joshi-Malafarina-Narayan (JMN) metric that represents the asymptotic equilibrium configuration of a collapsing star supported by tangential pressures as the starting configuration. We illustrate several novel features for the modified versions of the JNW and JMN spacetimes. In particular, we show that, depending on the values of the parameters involved the modified JNW metric may represents either a two way traversable wormhole or it may retain the original naked singularity. On the other hand, the SV modified JMN geometry is always a wormhole. Particle motion and observational aspects of these new geometries are investigated and are shown to posses interesting features. We also study the quasinormal modes of different branches of the regularised spacetime and explore their stability properties.