Rotating Relativistic Thin Disks as Sources of the Taub-NUT Solution

TL;DR

This paper models rotating relativistic thin disks derived from the Taub-NUT metric, revealing their composition as perfect fluids with negative energy density, instability under radial perturbations, and regions with superluminal particle velocities.

Contribution

It introduces a new class of rotating relativistic thin disk models based on the Taub-NUT solution using the displace, cut, and reflect method, analyzing their physical properties.

Findings

Disks are composed of perfect fluids with constant energy density and pressure.

Energy density is negative, but the effective Newtonian density is positive.

Disks are unstable under radial perturbations and contain regions with superluminal velocities.

Abstract

Rotating disks with nonzero radial pressure and finite radius are studied. The models are based in the Taub-NUT metric and constructed using the well-known ``displace, cut and reflect'' method. We find that the disks are made of perfect fluids with constant energy density and pressure. The energy density is negative, but the effective Newotnian density is possitive as the strong energy condition requires. We also find that the disks are not stable under radial perturbations and that there are regions of the disks where the particles move with superluminal velocities.