G\"{o}del black hole, closed timelike horizon, and the study of particle emissions

TL;DR

This paper investigates the properties of particle emissions from a five-dimensional rotating G"{o}del black hole, highlighting the inaccessibility of the closed timelike horizon to certain observers and analyzing emission spectra using semiclassical methods.

Contribution

It demonstrates that particles with positive angular momentum cannot reach the closed timelike horizon and applies the semiclassical complex path method to analyze various particle emissions.

Findings

Particles with positive angular momentum cannot reach the CTH.

The semiclassical approach verifies the Smarr formula for the G"{o}del black hole.

Analysis includes scalar, charged Dirac spinor, and vector emissions.

Abstract

We show that a particle, with positive orbital angular momentum, following an outgoing null/timelike geodesic, shall never reach the closed timelike horizon (CTH) present in the $(4+1)$-dimensional rotating G\"{o}del black hole space-time. Therefore a large part of this space-time remains inaccessible to a large class of geodesic observers, depending on the conserved quantities associated with them. We discuss how this fact and the existence of the closed timelike curves present in the asymptotic region make the quantum field theoretic study of the Hawking radiation, where the asymptotic observer states are a pre-requisite, unclear. However, the semiclassical approach provides an alternative to verify the Smarr formula derived recently for the rotating G\"{o}del black hole. We present a systematic analysis of particle emissions, specifically for scalars, charged Dirac spinors and vectors, from this black hole via the semiclassical complex path method.