Consistency of post-Newtonian waveforms with numerical relativity.

Area of Science:

• Astrophysics
• General Relativity
• Gravitational Waves

Background:

• General relativity predicts gravitational wave (GW) signatures from coalescing binary black holes.
• Post-Newtonian (PN) approximations are the primary method for generating waveform predictions for GW data analysis.
• The accuracy of PN approximations during the late-inspiral phase remains uncertain.

Purpose of the Study:

• To derive late-inspiral gravitational waveforms using direct numerical simulations of Einstein's equations.
• To compare the phasing of waveforms from numerical simulations with PN approximations.
• To assess the effectiveness of PN approximations in the crucial late-inspiral phase.

Main Methods:

• Direct numerical simulation of Einstein's field equations for binary black hole mergers.
• Comparison of waveform phasing between numerical relativity simulations and post-Newtonian (PN) approximations (2.5PN, 3PN, 3.5PN).
• Focus on the last approximately 14 cycles of gravitational radiation from equal-mass, nonspinning black holes.

Main Results:

• Waveform phasing from numerical simulations shows agreement with 2.5PN, 3PN, and 3.5PN approximations.
• The agreement is consistent with the internal error estimates of both simulation methods.
• Post-Newtonian approximations remain effective until the final orbit before merger.

Conclusions:

• Numerical relativity simulations provide a complementary approach to PN approximations for binary black hole mergers.
• Post-Newtonian approximations are reliable for analyzing gravitational wave data until the very end of the inspiral phase.
• This study validates the use of PN waveforms for a significant portion of the late-inspiral signal.