# Memory in de Sitter space and BMS-like supertranslations

## TL;DR

This paper explores how gravitational memory effects in de Sitter space are characterized by BMS-like supertranslations, extending the understanding of memory effects beyond flat spacetime to cosmological settings.

## Contribution

It demonstrates that gravitational memory in de Sitter spacetime can be described by BMS-like supertranslations without small separation assumptions, applicable to various FLRW universes.

## Key findings

- Memory in de Sitter space is parametrized by BMS-like supertranslations.
- A specific diffeomorphism corresponds to gravitational memory in different patches.
- Method applies to other cosmological models and possibly to massive messenger-mediated memory.

## Abstract

It is well known that the memory effect in flat spacetime is parametrized by the BMS supertranslation. We investigate the relation between the memory effect and diffeomorphism in de Sitter spacetime. We find that gravitational memory is parametrized by a BMS-like supertranslation in the static patch of de Sitter spacetime. We also show a diffeomorphism that corresponds to gravitational memory in the Poincare/cosmological patch. Our method does not need to assume the separation between the source and the detector to be small compared with the Hubble radius, and can potentially be applicable to other FLRW universes, as well as "ordinary memory" mediated by massive messenger particles.