Conformal isometry of the lukewarm Reissner-Nordstr\"om-de Sitter spacetime

TL;DR

This paper explores the conformal symmetry properties of the lukewarm Reissner-Nordström-de Sitter spacetime, extending known isometries and providing new interpretations of its geometric features.

Contribution

It extends the conformal isometry of Reissner-Nordström-de Sitter spacetime and offers an unphysical interpretation of the negative root.

Findings

Identifies a conformal isometry exchanging horizons

Extends the isometry to lukewarm case

Provides interpretation of the negative root

Abstract

It is known that the extremal Reissner-Nordstr\"om black hole possesses a discrete conformal isometry that exchanges the black hole horizon with infinity. It is also known that the Reissner-Nordstr\"om-de Sitter spacetime posseses a similar discrete conformal isometry which exchanges the event horizon of the black hole with the cosmological horizon. In this short paper we will continue this line of thought and extend the conformal isometry of the latter spacetime and give an unphysical interpretation of the negative root.