Using Full Information When Computing Modes of Post-Newtonian Waveforms From Inspiralling Compact Binaries in Circular Orbit

TL;DR

This paper improves the accuracy of gravitational waveform models from inspiraling compact binaries by computing individual modes to higher post-Newtonian order using radiative multipole moments, enhancing comparison with numerical simulations.

Contribution

It introduces a method to compute waveform modes to higher post-Newtonian order by analyzing radiative multipole moments instead of waveform polarization components.

Findings

Dominant (l=2, m=2) mode computed to 3PN order

Individual modes achieved higher PN order than previous methods

Facilitates better comparison between numerical and analytical waveforms

Abstract

The increasing sophistication and accuracy of numerical simulations of compact binaries (especially binary black holes) presents the opportunity to test the regime in which post-Newtonian (PN) predictions for the emitted gravitational waves are accurate. In order to confront numerical results with those of post-Newtonian theory, it is convenient to compare multipolar decompositions of the two waveforms. It is pointed out here that the individual modes can be computed to higher post-Newtonian order by examining the radiative multipole moments of the system, rather than by decomposing the 2.5PN polarization waveforms. In particular, the dominant (l = 2, m = 2) mode can be computed to 3PN order. Individual modes are computed to as high a post-Newtonian order as possible given previous post-Newtonian results.