CR Structures and Twisting Vacuum Spacetimes with Two Killing Vectors and Cosmological Constant: Type II and More Special

TL;DR

This paper derives a system of nonlinear ODEs to characterize twisting vacuum spacetimes with two Killing vectors and a cosmological constant, presenting various special solutions including known and new types, advancing the understanding of algebraically special spacetimes.

Contribution

It introduces a novel ODE framework for describing twisting type II and more special vacuum spacetimes with two Killing vectors, encompassing known solutions and discovering new classes.

Findings

Derived a system of two real ODEs for spacetime characterization

Presented explicit solutions for various Petrov types including Kerr and NUT

Identified a new class of type II solutions as limits of known solutions

Abstract

Based on the CR formalism of algebraically special spacetimes by Hill, Lewandowski and Nurowski, we derive a nonlinear system of two real ODEs, of which the general solution determines a twisting type II (or more special) vacuum spacetime with two Killing vectors (commuting or not) and at most seven real parameters in addition to the cosmological constant Lambda. To demonstrate a broad range of interesting spacetimes that these ODEs can capture, special solutions of various Petrov types are presented and described as they appear in this approach. They include Kerr-NUT, Kerr and Debney/Demia\'{n}ski's type II, Lun's type II and III (subclasses of Held-Robinson), MacCallum and Siklos' type III (Lambda<0), and the type N solutions (Lambda<>0) we found in an earlier paper, along with a new class of type II solutions as a nontrivial limit of Kerr and Debney's type II solutions. Also, we discuss a situation in which the two ODEs can be reduced to one. However, constructing the general solution still remains an open problem.