Probing missing physics from inspiralling compact binaries via time-frequency tracks

TL;DR

This paper introduces a novel time-frequency analysis method to test the validity of General Relativity in binary black hole systems by detecting deviations in gravitational wave signals, especially for eccentric systems and GW190814.

Contribution

It proposes a new consistency test based on stacking time-frequency pixel energies to identify deviations from GR in BBH gravitational wave signals.

Findings

Effective in detecting departures from GR in simulated data.

Able to analyze eccentric BBH systems and GW190814 for missing physics.

Demonstrates high sensitivity of the method with second-generation interferometers.

Abstract

The orbital evolution of binary black hole (BBH) systems is determined by the component masses and spins of the black holes and the governing gravity theory. Gravitational wave (GW) signals from the evolution of BBH orbits offer an unparalleled opportunity for examining the predictions of General Relativity (GR) and for searching for missing physics in the current waveform models. We present a method of stacking up the time-frequency pixel energies through the orbital frequency evolution with the flexibility of gradually shifting the orbital frequency curve along the frequency axis. We observe a distinct energy peak corresponding to the GW signal's quadrupole mode. If an alternative theory of gravity is considered and the analysis of the BBH orbital evolution is executed following GR, the energy distribution on the time-frequency plane will be significantly different. We propose a new consistency test to check whether our theoretical waveform explains the BBH orbital evolution. Through the numerical simulation of beyond-GR theory of gravity and utilizing the framework of second-generation interferometers, we demonstrate the efficiency of this new method in detecting any possible departure from GR. Finally, when applied to an eccentric BBH system and GW190814, which shows the signatures of higher-order multipoles, our method provides an exquisite probe of missing physics in the GR waveform models.