Dephasing in binary black hole mergers surrounded by scalar wave dark matter clouds

TL;DR

This study simulates black-hole mergers in scalar wave dark matter clouds, revealing how such environments can alter merger dynamics and gravitational wave signals, aiding the detection of light scalar fields like axion-like particles.

Contribution

It introduces a new simulation framework for black-hole binaries in scalar dark matter environments, improving initial data accuracy and exploring scalar mass effects on merger outcomes.

Findings

Scalar clouds can delay or accelerate mergers

Gravitational wave signals are modified by scalar fields

Enhanced modeling accuracy improves understanding of dark matter effects

Abstract

Scalar fields of masses between $10^{-21}\rm{eV}/c^2$ and $10^{-11} \rm{eV}/c^2$ can exhibit enhanced gravitational interactions with black holes, and form scalar clouds around them. Such a cloud modifies the dynamics of a coalescing black-hole binary, and the resulting gravitational waves may provide a new channel to detect light scalar fields, such as axion-like particles or wave-like dark matter candidates. In this work we simulate a series of black-hole mergers with mass ratios $q=1$ and $q=1/2$, immersed in an scalar field overdensity with masses in the range $M\mu_{\rm{S}} \in[0,1.0]$. To do so, we implemented a constraint-satisfying initial data solver based on the puncture method, we improved the accuracy of our open-source software Canuda to eighth order finite differences, and we reduced the initial orbital eccentricity. We investigate the impact of the scalar mass on the gravitational and scalar radiation. We find that binaries can undergo a delayed or an accelerated merger with respect to the vacuum. Our study highlights the challenge and importance of accurately modeling black-hole binaries in dark matter environments.