Binary neutron star inspiral, LIGO, and cosmology

The most promising anticipated source for the United States Laser Interferometer Gravitational-wave Observatory (LIGO) or its French/Italian counterpart VIRGO is the radiation emitted during the final moments of inspiral before the coalescence of a neutron star neutron star (ns-ns) binary system. The instruments that will operate in the LIGO facility will evolve over time, and the often-discussed “advanced detectors” will be sensitive to inspirals at luminosity distances greater than 1 Gpc. At such great distances the rate and character of the inspiral signal depends on the Hubble expansion, and several authors have investigated how LIGO and/or VIRGO binary inspiral observations can be used to measure the Hubble constant and other cosmological parameters4–6. This brief report summarizes a more lengthy investigation into estimates of the rate and character of the inspiral signals that LIGO and VIRGO should observe. A complete presentation, which also discusses black hole binaries, is in preparation for submission to Physical Review D.