Asymptotic dynamics and charges for FLRW spacetimes

Abstract

We investigate the asymptotia of decelerating and spatially flat FLRW spacetimes at future null infinity. We find that the asymptotic algebra of diffeomorphisms can be enlarged to the recently discovered Weyl-BMS algebra for asymptotically flat spacetimes by relaxing the boundary conditions. This algebra remains undeformed in the cosmological setting contrary to previous extensions of the BMS algebra. We then study the equations of motion for asymptotically FLRW spacetimes with finite fluxes and show that the dynamics is fully constrained by the energy-momentum tensor of the source. Finally, we propose an expression for the charges that are associated with the cosmological supertranslations and whose evolution equation features a novel contribution arising from the Hubble-Lemaître flow.

arXiv commentv1: 16+6 pages, 1 figure; v2: substantial improvements and clarifications in the text. This version matches published version in PRD

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Cited by in corpus (3)

• A Review of Gravitational Memory and BMS Frame Fixing in Numerical Relativity
• Using thermodynamics to learn gravitational wave physics
• Lectures on the Bondi--Metzner--Sachs group and related topics in infrared physics