Persistence of post-Newtonian amplitude structure in binary black hole mergers

Abstract

We analyze the spherical harmonic mode amplitudes of quasicircular, nonprecessing binary black hole mergers using 275 numerical relativity simulations from the SXS, RIT, and MAYA catalogs. We construct fits using the leading-order post-Newtonian (PN) dependence on intrinsic parameters, replacing the PN velocity with fit coefficients. We compare these to polynomial fits in symmetric mass ratio and spin. We analyze $(\ell ,m)$ modes with $\ell \le 4$ from late inspiral [$t=-500M$ relative to the $(2,2)$ peak] to postmerger ($t=40M$). For nonspinning systems, the $(2,2)$, $(2,1)$, and $(3,3)$ modes retain the leading-order PN dependence on mass ratio throughout the merger. Higher-order modes deviate from the PN dependence only near and after the merger, where polynomial fits of degree $N\le 3$ can capture the amplitude behavior up to $40M$. For aligned-spin systems at fixed mass ratio, the $(2,1)$ mode retains its PN spin dependence, while the $(3,2)$ and $(4,3)$ modes exhibit a quadratic spin dependence near merger. The PN-inspired fits lose accuracy with increasing mass ratio, particularly near merger. Results broadly agree across catalogs, though discrepancies appear in the $(3,1)$, $(4,2)$, and $(4,1)$ modes, likely from resolution differences. Our results clarify the extent to which PN structure persists in mode amplitudes. Although the fits cannot be fully interpreted within the PN formalism near merger, low-degree polynomial corrections to the PN amplitude Ansätze can capture strong-field behavior, enabling closed-form and efficient modeling of waveform amplitudes in this regime.

23 pages, 12 figures

References in corpus (25)

• Advanced Virgo: a 2nd generation interferometric gravitational wave detector
• Advanced LIGO
• GW190521: A Binary Black Hole Merger with a Total Mass of $150M_{\odot }$
• Calibration of Moving Puncture Simulations
• Using Full Information When Computing Modes of Post-Newtonian Waveforms From Inspiralling Compact Binaries in Circular Orbit
• Tidal Deformation and Dissipation of Rotating Black Holes
• Reducing phase error in long numerical binary black hole evolutions with sixth order finite differencing
• Numerical Relativity and Astrophysics
• GW231123: a Binary Black Hole Merger with Total Mass 190-265 $M_{\odot }$
• Dynamical Excision Boundaries in Spectral Evolutions of Binary Black Hole Spacetimes
• Modeling the source of GW150914 with targeted numerical-relativity simulations
• Measuring gravitational-wave higher-order modes
• Tidal heating and torquing of a Kerr black hole to next-to-leading order in the tidal coupling
• Key Elements of Robustness in Binary Black Hole Evolutions using Spectral Methods
• The Third RIT binary black hole simulations catalog
• LIGO Detector Characterization in the first half of the fourth Observing run
• The SXS Collaboration's third catalog of binary black hole simulations
• Spin contributions to the gravitational-waveform modes for spin-aligned binaries at the 3.5PN order
• Ringdown amplitudes of nonspinning eccentric binaries
• The nonspinning binary black hole merger scenario revisited
• Flexible mapping of ringdown amplitudes for nonprecessing binary black holes
• Defining eccentricity for spin-precessing binaries
• Ringdown mode amplitudes of precessing binary black holes
• Optimizing post-Newtonian parameters and fixing the BMS frame for numerical-relativity waveform hybridizations
• Second MAYA Catalog of Binary Black Hole Numerical Relativity Waveforms