BMS in Cosmology

Abstract

Symmetries play an interesting role in cosmology. They are useful in characterizing the cosmological perturbations generated during inflation and lead to consistency relations involving the soft limit of the statistical correlators of large-scale structure dark matter and galaxies overdensities. On the other hand, in observational cosmology the carriers of the information about these large-scale statistical distributions are light rays traveling on null geodesics. Motivated by this simple consideration, we study the structure of null infinity and the associated BMS symmetry in a cosmological setting. For decelerating Friedmann-Robertson-Walker backgrounds, for which future null infinity exists, we find that the BMS transformations which leaves the asymptotic metric invariant to leading order. Contrary to the asymptotic flat case, the BMS transformations in cosmology generate Goldstone modes corresponding to both scalar and tensor degrees of freedom which may exist at null infinity and perturb the asymptotic data. Therefore, BMS transformations generate physically inequivalent vacua as they populate the universe at null infinity with these physical degrees of freedom. We also discuss the gravitational memory effect when cosmological expansion is taken into account. In this case, there are extra contribution to the gravitational memory due to the tail of the retarded Green functions which are supported not only on the light-cone, but also in its interior. The gravitational memory effect can be understood also from an asymptotic point of view as a transition among cosmological BMS-related vacua.

33 pages, 4 figures

References in corpus (6)

• The gravitational-wave memory effect
• Conformal Symmetries of Adiabatic Modes in Cosmology
• Examination of a simple example of gravitational wave memory
• Soft-Pion Theorems for Large Scale Structure
• Classical Limit of Black Hole Quantum N-Portrait and BMS Symmetry
• Transverse-Traceless Gravitational Waves In A Spatially Flat FLRW Universe: Causal Structure from Dimension Reduction

Cited by in corpus (35)

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• Higher Spin Black Holes with Soft Hair
• The Cosmological Memory Effect
• Charge Algebra in Al(A)dS${}_n$ Spacetimes
• Goldstone origin of black hole hair from supertranslations and criticality
• BMS-like symmetries in cosmology
• Inferring fundamental spacetime symmetries with gravitational-wave memory: from LISA to the Einstein Telescope
• The sky pattern of the linearized gravitational memory effect
• Gravitational Wave Memory In dS${}_{4+2n}$ and 4D Cosmology
• Asymptotic Symmetries in de Sitter and Inflationary Spacetimes
• Memory in de Sitter space and BMS-like supertranslations
• Systematics of Adiabatic Modes: Flat Universes
• Symmetries of the Black Hole Interior and Singularity Regularization
• Soft pion theorem, asymptotic symmetry and new memory effect
• More On Cosmological Gravitational Waves And Their Memories
• Near Horizon Symmetries of the Non-Extremal Black Hole Solutions of Generalized Minimal Massive Gravity
• Cosmological horizons, Noether charges and entropy
• Gravitational wave memory and its tail in cosmology
• Notes on the gravitational, electromagnetic and axion memory effects
• Weinberg Soft Theorems from Weinberg Adiabatic Modes
• Electromagnetic Duality and the Electric Memory Effect
• Memory effect in Yang-Mills theory
• Inflation and Conformal Invariance: The Perspective from Radial Quantization
• Memory Effect in Anti-de Sitter Spacetime
• Asymptotic symmetries in spatially flat FRW
• Charges, conserved quantities and fluxes in de Sitter spacetime
• Supertranslations and Holography near the Horizon of Schwarzschild Black Holes
• Holography and black holes in asymptotically flat FLRW
• Inflation in Flatland
• Electromagnetic Memory Effect Induced by Axion Dark Matter
• Modular Fluctuations in Cosmology
• 1/c deformations of AdS${}_3$ boundary conditions and the Dym hierarchy
• Cosmological memory effect in scalar-tensor theories
• Inflationary gravitational wave background as a tail effect
• Overlap reduction function for gravitational wave detectors in an expanding Universe