On the stability of a superspinar

TL;DR

This paper investigates the stability of the superspinar, a hypothetical rapidly rotating compact object, demonstrating that it can be stable under many boundary conditions and that its modes decay over time, challenging previous assumptions.

Contribution

The study analytically shows that the superspinar can be stable under numerous boundary conditions, with modes that decay, thus questioning earlier claims of its instability.

Findings

Infinitely many boundary conditions lead to superspinar stability.

Modes of the superspinar decay over time.

Stability depends on physical boundary conditions.

Abstract

The superspinar proposed by Gimon and Horava is a rapidly rotating compact entity whose exterior is described by the over-spinning Kerr geometry. The compact entity itself is expected to be governed by superstringy effects, and in astrophysical scenarios it can give rise to interesting observable phenomena. Earlier it was suggested that the superspinar may not be stable but we point out here that this does not necessarily follow from earlier studies. We show, by analytically treating the Teukolsky equations by Detwiler's method, that in fact there are infinitely many boundary conditions that make the superspinar stable, and that the modes will decay in time. It follows that we need to know more on the physical nature of the superspinar in order to decide on its stability in physical reality.