Gravitational waves from nonspinning black hole-neutron star binaries: Dependence on equations of state

Journal Article · Sun Aug 15 04:00:00 EDT 2010 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.82.044049· OSTI ID:21420985

Kyutoku, Koutarou; Shibata, Masaru; Taniguchi, Keisuke ^[1]

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1. Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan)

We report results of a numerical-relativity simulation for the merger of a black hole-neutron star binary with a variety of equations of state (EOSs) modeled by piecewise polytropes. We focus, in particular, on the dependence of the gravitational waveform at the merger stage on the EOSs. The initial conditions are computed in the moving-puncture framework, assuming that the black hole is nonspinning and the neutron star has an irrotational velocity field. For a small mass ratio of the binaries (e.g., M{sub BH}/M{sub NS}=2, where M{sub BH} and M{sub NS} are the masses of the black hole and neutron star, respectively), the neutron star is tidally disrupted before it is swallowed by the black hole irrespective of the EOS. Especially for less-compact neutron stars, the tidal disruption occurs at a more distant orbit. The tidal disruption is reflected in a cutoff frequency of the gravitational-wave spectrum, above which the spectrum amplitude exponentially decreases. A clear relation is found between the cutoff frequency of the gravitational-wave spectrum and the compactness of the neutron star. This relation also depends weakly on the stiffness of the EOS in the core region of the neutron star, suggesting that not only the compactness but also the EOS at high density is reflected in gravitational waveforms. The mass of the 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 ratio of the binary, and only weakly on the EOS. Properties of the remnant disks are also analyzed.

• OSTI ID: 21420985
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 4 Vol. 82; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
79 ASTRONOMY AND ASTROPHYSICS
ANGULAR MOMENTUM
BINARY STARS
BLACK HOLES
CORRELATIONS
DENSITY
EQUATIONS
EQUATIONS OF STATE
GRAVITATIONAL WAVES
MASS
NEUTRON STARS
ORBITS
PARTICLE PROPERTIES
PHYSICAL PROPERTIES
SIMULATION
SPECTRA
SPIN
STARS
VELOCITY
WAVE FORMS