Anomalous Lense-Thirring precession in Kerr-Taub-NUT spacetimes

TL;DR

This paper reviews the exact Lense-Thirring precession in Kerr-Taub-NUT spacetime, revealing an anomaly where precession does not follow the inverse cube law near the horizon, with potential astrophysical implications.

Contribution

It identifies a unique anomaly in Lense-Thirring precession in Kerr-Taub-NUT spacetime and discusses its possible observational signatures in pulsars.

Findings

Precession peaks near the horizon and vanishes at a critical angle.

Anomaly is maximum at the polar region and vanishes towards the equator.

Inner horizon shifts to zero for specific angular momentum conditions.

Abstract

Exact Lense-Thirring (LT) precession in Kerr-Taub-NUT spacetime is reviewed. It is shown that the LT precession does not obey the general inverse cube law of distance at strong gravity regime in Kerr-Taub-NUT spacetime. Rather, it becomes maximum just near the horizon, falls sharply and becomes zero near the horizon. The precession rate increases again and after that it falls obeying the general inverse cube law of distance. This anomaly is maximum at the polar region of this spacetime and it vanishes after crossing a certain `critical' angle towards equator from pole. We highlight that this particular `anomaly' also arises in the LT effect at the interior spacetime of the pulsars and such a signature could be used to identify a role of Taub-NUT solutions in the astrophysical observations or equivalently, a signature of the existence of NUT charge in the pulsars. In addition, we show that if the Kerr-Taub-NUT spacetime rotates with the angular momentum $J=Mn$ (Mass$\times$Dual Mass), inner horizon goes to at $r=0$ and only {\it event horizon} exists at the distance $r=2M$.