Memory in de Sitter space and Bondi-Metzner-Sachs-like supertranslations

Abstract

It is well known that the memory effect in flat spacetime is parametrized by the Bondi-Metzner-Sachs (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 Friedmann-Lemaitre-Robertson-Walker universes, as well as ordinary memory mediated by massive messenger particles. © 2017 American Physical Society