Gravitational waves from the quasi-circular inspiral of compact binaries in Einstein-aether theory

TL;DR

This paper derives analytical gravitational waveforms and polarization modes for binary inspirals in Einstein-aether theory, enabling future tests of gravity beyond General Relativity with advanced detectors.

Contribution

It provides the first explicit post-Newtonian waveforms and parameterized post-Einsteinian parameters for Einstein-aether theory, including multiple polarization modes and propagation speeds.

Findings

Non-Einsteinian polarization modes depend on multiple harmonics.

Analytical expressions for waveforms and response functions are derived.

Framework allows for Bayesian tests of Einstein-aether theory with gravitational wave data.

Abstract

We study gravitational waves emitted by a binary system of non-spinning bodies in a quasi-circular inspiral within the framework of Einstein-aether theory. In particular, we compute explicitly and analytically the expressions for the time-domain and frequency-domain waveforms, gravitational wave polarizations, and response functions for both ground- and space-based detectors in the post-Newtonian approximation. We find that, when going beyond leading-order in the post-Newtonian approximation, the non-Einsteinian polarization modes contain terms that depend on both the first and the second harmonics of the orbital phase. We also calculate analytically the corresponding parameterized post-Einsteinian parameters, generalizing the existing framework to allow for different propagation speeds among scalar, vector and tensor modes, without assumptions about the magnitude of its coupling parameters, and meanwhile allowing the binary system to have relative motions with respect to the aether field. Such results allow for the easy construction of Einstein-aether templates that could be used in Bayesian tests of General Relativity in the future.