Prototype effective-one-body model for nonprecessing spinning inspiral-merger-ringdown waveforms

Abstract

This paper presents a tunable effective-one-body (EOB) model for black-hole (BH) binaries of arbitrary mass ratio and aligned spins. This new EOB model incorporates recent results of small-mass-ratio simulations based on Teukolsky's perturbative formalism. The free parameters of the model are calibrated to numerical-relativity simulations of nonspinning BH-BH systems of five different mass ratios and to equal-mass nonprecessing BH-BH systems with dimensionless BH spins ${\ensuremath{\chi}}_{i}\ensuremath{\simeq}\ifmmode\pm\else\textpm\fi{}0.44$. The present analysis focuses on the orbital dynamics of the resulting EOB model, and on the dominant $(\ensuremath{\ell},m)=(2,2)$ gravitational-wave mode. The calibrated EOB model can generate inspiral-merger-ringdown waveforms for nonprecessing, spinning BH binaries with any mass ratio and with individual BH spins $\ensuremath{-}1\ensuremath{\le}{\ensuremath{\chi}}_{i}\ensuremath{\lesssim}0.7$. Extremizing only over time and phase shifts, the calibrated EOB model has overlaps larger than 0.997 with each of the seven numerical-relativity waveforms for total masses between $20{M}_{\ensuremath{\bigodot}}$ and $200{M}_{\ensuremath{\bigodot}}$, using the Advanced LIGO noise curve. We compare the calibrated EOB model with two additional equal-mass highly spinning (${\ensuremath{\chi}}_{i}\ensuremath{\simeq}\ensuremath{-}0.95,+0.97$) numerical-relativity waveforms, which were not used during calibration. We find that the calibrated model has an overlap larger than 0.995 with the simulation with nearly extremal antialigned spins. Extension of this model to black holes with aligned spins ${\ensuremath{\chi}}_{i}\ensuremath{\gtrsim}0.7$ requires improvements of our modeling of the plunge dynamics and inclusion of higher-order PN spin terms in the gravitational-wave modes and radiation-reaction force.