Geodesics on a Kerr-Newman-(anti-)de Sitter instanton

TL;DR

This paper analyzes the behavior of geodesics in Kerr-Newman-(anti-)de Sitter instantons, revealing insights into their trajectories, special features like theta horizons, and stable equilibrium orbits in complex spacetime geometries.

Contribution

It provides a detailed characterization of geodesic trajectories and stable orbits in Kerr-Newman-(anti-)de Sitter instantons using Hamilton-Jacobi integrals.

Findings

Identification of geodesic behavior near horizons

Analysis of regions with angular degeneracy ('theta horizons')

Characterization of stable equilibrium orbits

Abstract

We study geodesics along a noncompact Kerr-Newman instanton, where the asymptotic geometry is either de Sitter or anti-de Sitter. We use first integrals for the Hamilton-Jacobi equation to characterize trajectories both near and away from horizons. We study the interaction of geodesics with special features of the metric, particularly regions of angular degeneracy or "theta horizons" in the de Sitter case. Finally, we characterize a number of stable equilibrium orbits.