PULSAR STATISTICS .3. NEUTRON-STAR BINARIES

We use a detailed computer simulation of the galactic pulsar populatio n to estimate the number of neutron star-neutron star (NS-NS) binaries in the Galaxy. Our calculations are based on the three known systems of this class, PSRs B1534+12, B1913+16 and B2303+46, and use the lates t results from sensitive pulsar surveys covering a large area of sky. We estimate that there are similar to 240 potentially observable NS-NS binaries in the Galaxy. As B1534+12 and B1913+16 will eventually merg e due to the emission of gravitational radiation in a known time-scale , we can deduce the galactic merging rate R of NS-NS binaries; we esti mate R similar to 10(-7) yr(-1). Taking account of several factors whi ch affect the number of NS-NS systems that can be detected, we arrive at a more realistic nominal value of R similar to 3 x 10(-6) yr(-1). T hus we have to look far beyond the Galaxy to the Gpc range in order to witness several NS-NS star mergings per year. The next generation of gravitational wave detectors are expected to have sensitivities approa ching that required to probe to such distances.