A novel category of environmental effect in gravitational waves from binaries perturbed by periodic forces

TL;DR

This paper introduces a new model for gravitational wave phase perturbations caused by periodic forces in binary systems, highlighting their detectability and distinct features from secular effects, with implications for astrophysical observations.

Contribution

The study develops a post-Newtonian waveform model for periodic environmental effects on gravitational waves, demonstrating their detectability and unique signatures.

Findings

Periodic phase perturbations are distinguishable from secular dephasing.

Such perturbations can be detected in various astrophysical scenarios.

Periodic effects do not degenerate with binary parameters in waveform analysis.

Abstract

We study the gravitational wave (GW) emission of sources perturbed by periodic dynamical forces which do not cause secular evolution in the orbital elements. We construct a corresponding post-Newtonian waveform model and provide estimates for the detectability of the resulting GW phase perturbations, for both space-based and future ground-based detectors. We validate our results by performing a set of Bayesian parameter recovery experiments with post-Newtonian waveforms. We find that, in stark contrast to the more commonly studied secular dephasing, periodic phase perturbations do not suffer from degeneracies with any of the tested vacuum binary parameters. We discuss the applications of our findings to a range of possible astrophysical scenarios, finding that such periodic perturbations may be detectable for massive black hole binaries embedded in circum-binary discs, extreme mass-ratio inspirals in accretion discs, as well as stellar-mass compact objects perturbed by tidal fields. We argue that modelling conservative sub-orbital dynamics opens up a promising new avenue to detect environmental effects in binary sources of GWs that should be included in state-of-the-art waveform templates.