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Hydrodynamics of coalescing binary neutron stars: Ellipsoidal treatmentWe employ an approximate treatment of dissipative hydrodynamics in three dimensions to study the coalescence of binary neutron stars driven by the emission of gravitational waves. The stars are modeled as compressible ellipsoids obeying a polytropic equation of state; all internal fluid velocities are assumed to be linear functions of the coordinates. The hydrodynamics equations then reduce to a set of coupled ordinary differential equations for the evolution of the principal axes of the ellipsoids, the internal velocity parameters, and the binary orbital parameters. Gravitational radiation reaction and viscous dissipation are both incorporated. We set up exact initial binary equilibrium configurations and follow the transition from the quasi-static, secular decay of the orbit at large separation to the rapid dynamical evolution of the configurations just prior to contact. A hydrodynamical instability resulting from tidal interactions significantly accelerates the coalescence at small separation, leading to appreciable radial infall velocity and tidal lag angles near contact. This behavior is reflected in the gravitational waveforms and may be observable by gravitational wave detectors under construction. In cases where the neutron stars have spins which are not aligned with the orbital angular momentum, the spin-induced quadrupole moment can lead to precession of the orbital plane and therefore modulation of the gravitational wave amplitude even at large orbital radius. However, the amplitude of the modulation is small for typical neutron star binaries with spins much smaller than the orbital angular momentum.
Document ID
19950054621
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Lai, Dong
(Cornell University Ithaca, NY, United States)
Shapiro, Stuart L.
(Cornell University Ithaca, NY, United States)
Date Acquired
August 16, 2013
Publication Date
April 20, 1995
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 443
Issue: 2
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
95A86220
Funding Number(s)
CONTRACT_GRANT: NSF AST-91-19475
CONTRACT_GRANT: NAGW-2394
CONTRACT_GRANT: NAGW-2364
Distribution Limits
Public
Copyright
Other

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