Gravitational Wave Beacons

TL;DR

This paper investigates the complex precession and flip dynamics of spinning, unequal-mass binary black holes through numerical simulations, revealing distinctive gravitational wave signatures that depend on polarization and direction.

Contribution

It provides the first detailed numerical analysis of long-term orbital angular momentum flips in unequal-mass, spinning black hole binaries with novel polarization-dependent waveform features.

Findings

Demonstrated full L-flip cycles in binary black hole mergers.

Identified polarization-dependent amplitude variations at precessional frequencies.

Highlighted observational implications for gravitational wave detection and parameter estimation.

Abstract

We explore spinning, precessing, unequal mass binary black holes to display the long term orbital angular momentum, $\vec{L}$, flip dynamics. We study two prototypical cases of binaries with mass ratios $q=1/7$ and $q=1/15$ and a misaligned spin of the large black hole (with an intrinsic spin magnitude of $S_2/m_2^2=0.85$). We conduct full numerical simulations, for nearly 14 and 18 orbits respectively, to evolve the binary down to merger and display a full $L$-flip cycle. The pattern of radiation of such systems is particularly interesting, displaying strong polarization-dependent variation of amplitudes at precessional frequencies, leading to distinctive observational consequences for ground, space, and pulsar timing based gravitational wave detectors. These waveform features are strongly directional dependent and measurements of gravitational waves polarizations can be exploited to disentangle the binary's parameters in various astrophysical scenarios.