THE GALACTIC MERGER-RATE OF (NS,NS) BINARIES .1. PERSPECTIVE FOR GRAVITY-WAVE DETECTORS

We use a detailed binary-evolution model to predict the rare for merge r events of neutron-star/neutron-star binaries, for various extreme as sumptions about initial conditions and evolutionary mechanisms. The mo dels in which neutron stars acquire a kick velocity at birth of simila r to 450 km/s predict a merger rate in the Galaxy, and consequently a rate for bursts of gravitational waves, of at least similar to 10(-5) yr(-1). This rate is slightly larger than the 'best guess' derived fro m three observed (ns, ns) binaries (Phinney 1991). Also the galactic p opulation produced with these models is consistent with the result fro m Narayan et al. (1991). Models without kick velocities produce a gala ctic population that is two orders of magnitude larger than the models with a high-velocity kick. These models are also incompatible with Ba iles'(1995) upper limit for coalescence rates of(ns, ns) binary pulsar s. The merger rates for these models are an order of magnitude larger than for the models with a kick.