Evolution of Binary Black-Hole Spacetimes

TLDR

The study demonstrates early success in evolving binary black‑hole spacetimes using a numerical code based on generalized harmonic coordinates. The authors use a generalized harmonic coordinate numerical code to evolve an equal‑mass, nonspinning binary black‑hole system through plunge, merger, and ringdown. The scheme successfully evolves binaries long enough to capture orbit, merger, and gravitational waves, yielding a Kerr remnant with spin a≈0.70 and radiating roughly 5 % of the initial rest mass as gravitational waves.

Abstract

We describe early success in the evolution of binary black-hole spacetimes with a numerical code based on a generalization of harmonic coordinates. Indications are that with sufficient resolution this scheme is capable of evolving binary systems for enough time to extract information about the orbit, merger, and gravitational waves emitted during the event. As an example we show results from the evolution of a binary composed of two equal mass, nonspinning black holes, through a single plunge orbit, merger, and ringdown. The resultant black hole is estimated to be a Kerr black hole with angular momentum parameter a approximately 0.70. At present, lack of resolution far from the binary prevents an accurate estimate of the energy emitted, though a rough calculation suggests on the order of 5% of the initial rest mass of the system is radiated as gravitational waves during the final orbit and ringdown.