On symmetries and charges at spatial infinity

TL;DR

This paper explores the structure of spacetime symmetries at spatial infinity using the Bondi metric, revealing an extended BMS symmetry group with additional abelian symmetries, and shows how imposing certain conditions reduces these symmetries.

Contribution

It demonstrates that without the determinant condition, the symmetry group at spatial infinity includes the BMS group plus extra abelian symmetries, expanding understanding of asymptotic symmetries.

Findings

Symmetries at spatial infinity form the BMS group plus additional abelian symmetries.

Imposing the determinant condition reduces symmetries, removing spatial translations.

Extended symmetry structure depends on the choice of metric conditions.

Abstract

Following the recent work of Henneaux and Troessaert, which revisits the problem of spacetime symmetries at spatial infinity, we analyze this problem using the Bondi metric without determinant condition as our starting point. It turns out that in this case the symmetries at spatial infinity form the BMS symmetry appended with an additional infinite set of abelian symmetries. We furthermore find that imposing the determinant condition to the Bondi metric would result in a drastic reduction of symmetries, with no spatial (super) translations present.