Self-force framework for transition-to-plunge waveforms

TL;DR

This paper develops a new multiscale framework to accurately model the transition from inspiral to plunge in gravitational waveforms for asymmetric mass ratio binaries, improving waveform predictions near the innermost stable orbit.

Contribution

It introduces the transition-to-plunge expansion within a multiscale framework and constructs second post-leading transition-to-plunge waveforms, enabling rapid and more accurate waveform generation.

Findings

Validated against numerical relativity simulations

Constructed 2PLT waveforms for transition-to-plunge phase

Framework allows higher-order waveform development

Abstract

Compact binaries with asymmetric mass ratios are key expected sources for next-generation gravitational wave detectors. Gravitational self-force theory has been successful in producing post-adiabatic waveforms that describe the quasi-circular inspiral around a non-spinning black hole with sub-radian accuracy, in remarkable agreement with numerical relativity simulations. Current inspiral models, however, break down at the innermost stable circular orbit, missing part of the waveform as the secondary body transitions to a plunge into the black hole. In this work we derive the transition-to-plunge expansion within a multiscale framework and asymptotically match its early-time behaviour with the late inspiral. Our multiscale formulation facilitates rapid generation of waveforms: we build second post-leading transition-to-plunge waveforms, named 2PLT waveforms. Although our numerical results are limited to low perturbative orders, our framework contains the analytic tools for building higher-order waveforms consistent with post-adiabatic inspirals, once all the necessary numerical self-force data becomes available. We validate our framework by comparing against numerical relativity simulations, surrogate models and the effective one-body approach.