Constraining Dipole Radiation with Multiband Gravitational Waves from Eccentric Binary Black Holes

TL;DR

This paper develops a Bayesian inference pipeline for multiband gravitational wave observations of eccentric binary black holes, aiming to constrain dipole radiation deviations from general relativity.

Contribution

It introduces the first multiband Bayesian inference method that simultaneously models eccentricity and dipole radiation effects in binary black hole signals.

Findings

Eccentricity introduces degeneracies that weaken dipole constraints.

One year of TianQin or LISA data can constrain dipole parameters to |b| ≲ 10^{-7}.

Multiband GW observations are promising for testing dipole radiation.

Abstract

Dipole-radiation-like deviations from general relativity are most prominent during the early inspiral of compact binaries, making space-ground multiband observations a potential probe of such effects. In the same regime, orbital eccentricity can leave a significant imprint on the waveform and is therefore essential for robust dipole-radiation constraints. For the first time we present a multiband Bayesian inference pipeline for stellar-mass binary black holes that simultaneously incorporates eccentricity and a theory-agnostic dipole-radiation correction. We find strong degeneracies among the dipole parameter, chirp mass, and eccentricity, which substantially weaken the inferred dipole constraints when eccentricity is included. Even so, for a GW231123-like source, one year of TianQin or LISA observation with ground-informed priors from a next-generation detector network can still constrain the dipole parameter to $|b|\lesssim\mathcal{O}(10^{-7})$ under inference with noisy data. Our results show that multiband binary black hole observations provide a promising and distinct channel for testing theory-agnostic dipole radiation, while also highlighting the need for more complete waveform modeling in future precision tests of gravity.