Gravitational waves from binary black hole mergers surrounded by scalar field clouds: Numerical simulations and observational implications

TL;DR

This paper demonstrates how gravitational-wave signals from binary black hole mergers can be used to detect or constrain surrounding scalar field clouds, potentially revealing properties of ultra-light bosons.

Contribution

It introduces a numerical waveform model for scalar-field-BBH mergers and shows how these signals can be distinguished from standard black hole mergers using current gravitational-wave detectors.

Findings

Larger scalar field parameters cause noticeable changes in waveform amplitude and frequency.

Waveforms can be modeled as chirping sine-Gaussians with over 95% match.

Observations at 450 Mpc can constrain scalar field strength to -3 level.

Abstract

We show how gravitational-wave observations of binary black hole (BBH) mergers can constrain the physical characteristics of a scalar field cloud parameterized by mass $\tilde{\mu}$ and strength $\phi_0$ that may surround them. We numerically study the inspiraling equal-mass, non-spinning BBH systems dressed in such clouds, focusing especially on the gravitational-wave signals emitted by their merger-ringdown phase. These waveforms clearly reveal that larger values of $\tilde{\mu}$ or $\phi_0$ cause bigger changes in the amplitude and frequency of the scalar-field-BBH ringdown signals. We show that the numerical waveforms of scalar-field-BBHs can be modelled as chirping sine-Gaussians, with matches in excess of 95%. This observation enables one to employ computationally expensive Bayesian studies for estimating the parameters of such binaries. Using our chirping sine-Gaussian signal model we establish that observations of BBH mergers at a distance of 450 Mpc will allow to distinguish BBHs without any scalar field from those with a field strength $\phi_0 \gtrsim 5.5\times 10^{-3}$, at any fixed value of $\tilde \mu \in [0.3,0.8]$, with 90% confidence or better, in single detectors with Advanced LIGO/Virgo type sensitivities. This provides hope for the possibility of determining or constraining the mass of ultra-light bosons with gravitational-wave observations of BBH mergers.