Gravitational Wave Signatures Induced by Dark Fluid Accretion in Binary Systems

TL;DR

This paper explores how dark fluid accretion affects gravitational wave signals from binary systems, revealing phase shifts influenced by the fluid's properties and assessing effects of cosmological singularities on orbital dynamics.

Contribution

It introduces a framework combining local and global fluid interactions in binary systems, advancing understanding of fluid effects on gravitational waveforms and potential for probing dark energy properties.

Findings

Dark fluid accretion causes measurable de-phasing in gravitational waves.

Equation of state influences the phase shift magnitude.

Cosmological singularities deform orbits but minimally affect de-phasing.

Abstract

We investigate the impact of dark fluid accretion on gravitational waveforms emitted by a compact binary system consisting of a supermassive black hole and a stellar-mass black hole. Using a Lagrangian framework with 1~PN and 2.5~PN corrections, we analyze the effects of the spherically symmetric accretion of a fluid with steady-state flow, including those characterized by an equation of state parameter resembling dark energy, on the binary's dynamics. We validate our approach by comparing it with previous studies in the common region of validity and extend the analysis to include both local effects, such as dynamical friction, and global gravitational interactions with the stellar-mass black hole, focusing on their dependence on the fluid's properties. Our analysis reveals that these interactions induce de-phasing in gravitational waveforms, with the phase shift influenced by the fluid's equation of state and energy density. We also extend the study to sudden cosmological singularities, finding that, although they can deform the binary's orbit from initially circular to elliptical, their effect on de-phasing is negligible for cosmologically relevant energy densities. By incorporating both the local and global gravitational interactions of a fluid on a two-body system into the equations of motion, this preliminary study provides a framework for understanding the interplay between fluid dynamics and gravitational wave emissions in astrophysical systems. It further reinforces the potential for probing the properties of astrophysically relevant fluids through gravitational wave observations.