May 6 – 10, 2024
US/Eastern timezone

A New Criterion for Angular Momentum at Null Infinity

May 10, 2024, 2:30 PM
15m
FAU FTL Room 131

FAU FTL Room 131

Boundaries, Symmetries, and Classical aspects Boundaries, Symmetries, and Classical aspects

Speaker

Daniel Paraizo (Penn State)

Description

The enhancement of the symmetry group for asymptotically flat spacetimes from the Poincare group to the infinite-dimensional BMS group gives a rich structure to the theory. The existence of supertranslations in the BMS group plays a key role in a variety of asymptotic phenomenon. In particular, there is a well-known "supertranslation ambiguity" in defining the angular momentum of an isolated gravitational system. Although this should be viewed as a generic feature of the theory, it does present the issue that, apriori, there may not seem to be a "preferred" definition of angular momentum. We propose a new criterion to assess the viability of definitions of angular momentum at null infinity: cross-section continuity. Although the Dray-Streubel (DS) definition automatically satisfies this condition due to the existence of a flux, the one-parameter family of angular momenta proposed by Compere and Nichols (CN) - which encompasses multiple other definitions - does not. We also verify the Chen-Wang-Yao (CWY) definition is cross-section continuous.

Author

Daniel Paraizo (Penn State)

Presentation materials