Unambiguous angular momentum of radiative spacetimes and asymptotic structure in terms of the center of mass system

TL;DR

This paper introduces an unambiguous definition of angular momentum for radiative spacetimes that resolves supertranslation ambiguities and establishes a center of mass frame at null infinity, enhancing understanding of asymptotic structure.

Contribution

It provides a novel, supertranslation-invariant definition of intrinsic angular momentum and a clear notion of the center of mass frame at null infinity.

Findings

Defined supertranslation-invariant angular momentum

Established a center of mass frame at null infinity

Presented asymptotic structure equations for vacuum spacetimes

Abstract

We present a definition of angular momentum for radiative spacetimes which does not suffer from any ambiguity of supertranslations. We succeed in providing an appropriate notion of {\it intrinsic} angular momentum; and at the same time a definition of center of mass frame at future null infinity. We use the center of mass frame to present the asymptotic structure equations for vacuum spacetimes.