Kerr black holes in horizon-generating form

TL;DR

This paper introduces new coordinate systems for Kerr black holes that extend the Kruskal form, using horizon-based dual-null foliations and generalized radial functions to better understand their structure.

Contribution

It presents a novel coordinate framework for Kerr black holes based on horizon-generating dual-null foliations, generalizing Schwarzschild coordinates.

Findings

Coordinates describe non-degenerate Kerr black holes in dual-null form

Generalization of the Regge-Wheeler radial function

Extension of Kruskal coordinates to rotating black holes

Abstract

New coordinates are given which describe non-degenerate Kerr black holes in dual-null foliations based on the outer (or inner) horizons, generalizing the Kruskal form for Schwarzschild black holes. The construction involves an area radius for the transverse surfaces and a generalization of the Regge-Wheeler radial function, both functions of the original radial coordinate only.