Phys. Rev. D, 110, 065002 (2024)

Linearized gravity and soft graviton theorem in de Sitter spacetime

PuJian Mao and Bochen Zhou

Center for Joint Quantum Studies and Department of Physics, School of Science, Tianjin University, 135 Yaguan Road, Tianjin 300350, China.

* pjmao@tju.edu.cn, zhoubch@tju.edu.cn

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.