On Propagation of Energy Flux in de Sitter Spacetime

TL;DR

This paper investigates how energy flux propagates in de Sitter spacetime, showing that it is sharp and consistent across different approaches, with implications for understanding energy transfer in cosmological models.

Contribution

It introduces a covariant phase space method to compute energy flux in de Sitter spacetime and relates it to the Isaacson stress-tensor approach, highlighting the sharpness of energy propagation.

Findings

Energy flux integrand is the same on the horizon and null infinity.

Propagation of energy flux in de Sitter spacetime is sharp.

Energy flux expressions are consistent across different formalisms.

Abstract

In this paper, we explore propagation of energy flux in the future Poincar\'e patch of de Sitter spacetime. We present two results. First, we compute the flux integral of energy using the symplectic current density of the covariant phase space approach on hypersurfaces of constant radial physical distance. Using this computation we show that in the tt-projection, the integrand in the energy flux expression on the cosmological horizon is same as that on the future null infinity. This suggests that propagation of energy flux in de Sitter spacetime is sharp. Second, we relate our energy flux expression in tt-projection to a previously obtained expression using the Isaacson stress-tensor approach. We also comment on the energy flux computation in TT-gauge on hypersurfaces of constant radial physical distance.