Computing the Complete Gravitational Wavetrain from Relativistic Binary Inspiral

TL;DR

This paper introduces a numerical method to generate the complete gravitational wavetrain from the late inspiral phase of binary neutron stars using full general relativity, producing detailed wave cycles.

Contribution

The novel approach combines quasi-equilibrium sequences and energy flux calculations to produce continuous gravitational waveforms from binary inspirals.

Findings

Produced 214 gravitational wave cycles in a prototype simulation.

Demonstrated the method's ability to generate continuous wavetrains from inspiral data.

Discussed potential improvements and applications for other inspiral scenarios.

Abstract

We present a new method for generating the nonlinear gravitational wavetrain from the late inspiral (pre-coalescence) phase of a binary neutron star system by means of a numerical evolution calculation in full general relativity. In a prototype calculation, we produce 214 wave cycles from corotating polytropes, representing the final part of the inspiral phase prior to reaching the ISCO. Our method is based on the inequality that the orbital decay timescale due to gravitational radiation is much longer than an orbital period and the approximation that gravitational radiation has little effect on the structure of the stars. We employ quasi-equilibrium sequences of binaries in circular orbit for the matter source in our field evolution code. We compute the gravity-wave energy flux, and, from this, the inspiral rate, at a discrete set of binary separations. From these data, we construct the gravitational waveform as a continuous wavetrain. Finally, we discuss the limitations of our current calculation, planned improvements, and potential applications of our method to other inspiral scenarios.