Linearized gravity and soft graviton theorem in de Sitter spacetime

TL;DR

This paper investigates linearized gravity in de Sitter spacetime, revealing how near horizon symmetries relate to soft graviton theorems through charge calculations and specific fall-off conditions.

Contribution

It establishes a connection between near horizon symmetries and soft graviton theorems in de Sitter space, providing explicit charge computations and fall-off conditions.

Findings

Near horizon supertranslation charge computed.

Soft graviton theorem derived from Ward identity.

Proper fall-off conditions identified.

Abstract

We study the linearized gravity theory in the Newman-Unti gauge in the near horizon region of the de Sitter spacetime. The linearized Einstein equation involves the cosmological constant. The near horizon symmetry consists of near horizon supertranslation and near horizon superrotation. We compute the near horizon supertranslation charge and find the proper near horizon fall-off conditions which uncover a soft graviton theorem from the Ward identity of the near horizon supertranslation.