Power radiated by a binary system in a de Sitter Universe

TL;DR

This paper calculates the gravitational wave power emitted by a binary system in a de Sitter universe, addressing limitations of previous methods and providing tailored techniques for this spacetime.

Contribution

It introduces a method to compute gravitational wave power in de Sitter spacetime, overcoming previous approximation limitations and confirming consistency with FLRW results in high-frequency regimes.

Findings

Derived the power emitted by binaries in de Sitter space.

Showed equivalence of de Sitter and FLRW power expressions in high-frequency limit.

Provided a framework for gravitational wave analysis in accelerated expansion backgrounds.

Abstract

Gravitational waves emitted by high redshift sources propagate through various epochs of the Universe including the current era of measurable, accelerated expansion. Historically, the calculation of gravitational wave power on cosmological backgrounds is based on various simplifications, including a $1/r$-expansion and the use of an algebraic projection to retrieve the radiative degrees of freedom. On a de Sitter spacetime, recent work has demonstrated that many of these calculational techniques and approximations do not apply. Here we calculate the power emitted by a binary system on a de Sitter background using techniques tailored to de Sitter spacetime. The common expression for the power radiated by this source in an FLRW spacetime, calculated using far wave-zone techniques, gives the same expression as the late time expansion specialized to the de Sitter background in the high-frequency approximation.