Spin and Center of Mass in Axially Symmetric Einstein-Maxwell Spacetimes

TL;DR

This paper defines and derives equations for the center of mass and angular momentum in axially symmetric Einstein-Maxwell spacetimes, using Newman-Unti cuts at null infinity, with implications for gravitational and electromagnetic radiation emission.

Contribution

It introduces a new framework for analyzing center of mass and angular momentum in axially symmetric spacetimes using Newman-Unti cuts, extending previous approaches.

Findings

Derived equations of motion for center of mass and angular momentum.

Analyzed consequences of the new formulation.

Commented on potential generalizations to broader spacetimes.

Abstract

We give a definition and derive the equations of motion for the center of mass and angular momentum of an axially symmetric, isolated system that emits gravitational and electromagnetic radiation. A central feature of this formulation is the use of Newman-Unti cuts at null infinity that are generated by worldlines of the spacetime. We analyze some consequences of the results and comment on the generalization of this work to general asymptotically flat spacetimes.