Session H1 - Issues in Gravitational Radiation.
INVITED session, Sunday morning, April 29
Grand Ballroom North/Central, Renaissance Hotel$
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 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 (QE) 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. Using these data, we construct the gravitational waveform as a continuous wavetrain. We conclude that the QE scheme provides a promising technique for constructing the complete wavetrain from binary inspiral outside the ISCO, where the fields are strong but where following the system for more than a few orbits by direct numerical integration of the exact equations is prohibitive. We discuss the limitations of our current calculation, planned improvements, and potential applications of our QE method to other inspiral scenarios. A video highlighting key features of our calculation will be shown.