# Gravitational waves from nonspinning black hole-neutron star binaries: dependence on equations of state - Astrophysics > High Energy Astrophysical Phenomena

Gravitational waves from nonspinning black hole-neutron star binaries: dependence on equations of state - Astrophysics > High Energy Astrophysical Phenomena - Download this document for free, or read online. Document in PDF available to download.

Abstract: We report results of a numerical-relativity simulation for the merger of ablack hole-neutron star binary with a variety of equations of state EOSsmodeled by piecewise polytropes. We focus in particular on the dependence ofthe gravitational waveform at the merger stage on the EOSs. The initialconditions are computed in the moving-puncture framework, assuming that theblack hole is nonspinning and the neutron star has an irrotational velocityfield. For a small mass ratio of the binaries e.g., MBH-MNS = 2 where MBH andMNS are the masses of the black hole and neutron star, respectively, theneutron star is tidally disrupted before it is swallowed by the black holeirrespective of the EOS. Especially for less-compact neutron stars, the tidaldisruption occurs at a more distant orbit. The tidal disruption is reflected ina cutoff frequency of the gravitational-wave spectrum, above which the spectrumamplitude exponentially decreases. A clear relation is found between the cutofffrequency of the gravitational-wave spectrum and the compactness of the neutronstar. This relation also depends weakly on the stiffness of the EOS in the coreregion of the neutron star, suggesting that not only the compactness but alsothe EOS at high density is reflected in gravitational waveforms. The mass ofthe disk formed after the merger shows a similar correlation with the EOS,whereas the spin of the remnant black hole depends primarily on the mass ratioof the binary, and only weakly on the EOS. Properties of the remnant disks arealso analyzed.

Author: ** Koutarou Kyutoku, Masaru Shibata, Keisuke Taniguchi**

Source: https://arxiv.org/