Observing spinning neutron-star black-hole mergers with second generation gravitational-wave observatories

Ian Harry

October 17, 2013

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Abstract: The first direct detection of neutron-star–black-hole binaries will likely be made with the gravitational wave observatories Advanced LIGO and Advanced Virgo. Gravitational-wave searches rely on using waveform models that accurately represent the expected gravitational-wave signal. This signal will depend on the masses of the black hole and the neutron star and also the angular momentum of both components. This angular momentum will affect the dynamics of the system and alter the phase evolution of the emitted gravitational-wave signal. In this talk we demonstrate how neglecting the black hole’s angular momentum in the waveform models used in gravitational-wave searches will affect the observation rate of neutron-star–black-hole coalescences. We investigate the improvement in observation rate that will be gained if waveform models with non-zero angular momentum aligned with the orbital angular momentum are used. Systems that will not be detected with aligned-spin waveforms are ones where precession of the orbital plane causes the gravitational-wave signal to match poorly with non-precessing filter waveforms. We identify the regions of parameter space where such systems occur and suggest methods for searching for highly precessing neutron-star–black-hole binaries.