Computing the Complete Gravitational Wavetrain from Relativistic Binary Inspiral
Matthew D. Duez Thomas W. Baumgarte Stuart L. Shapiro
University of Illinois at Urbana-Champaign
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 fact 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.