Dynamical evolution of black hole-neutron star binaries in general relativity: Simulations of tidal disruption

Journal Article · Sun Jan 15 00:00:00 EST 2006 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.73.0· OSTI ID:20795729

Faber, Joshua A; Shapiro, Stuart L; Taniguchi, Keisuke ^[1]; Baumgarte, Thomas W ^[1]; Rasio, Frederic A ^[2]

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1. Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)
2. Department of Physics and Astronomy, Northwestern University, Evanston, Illinois, 60208 (United States)

We calculate the first dynamical evolutions of merging black hole-neutron star binaries that construct the combined black hole-neutron star spacetime in a general relativistic framework. We treat the metric in the conformal flatness approximation, and assume that the black hole mass is sufficiently large compared to that of the neutron star so that the black hole remains fixed in space. Using a spheroidal spectral methods solver, we solve the resulting field equations for a neutron star orbiting a Schwarzschild black hole. The matter is evolved using a relativistic, Lagrangian, smoothed particle hydrodynamics (SPH) treatment. We take as our initial data recent quasiequilibrium models for synchronized neutron star polytropes generated as solutions of the conformal thin-sandwich (CTS) decomposition of the Einstein field equations. We are able to construct from these models relaxed SPH configurations whose profiles show good agreement with CTS solutions. Our adiabatic evolution calculations for neutron stars with low-compactness show that mass transfer, when it begins while the neutron star orbit is still outside the innermost stable circular orbit, is more unstable than is typically predicted by analytical formalisms. This dynamical mass loss is found to be the driving force in determining the subsequent evolution of the binary orbit and the neutron star, which typically disrupts completely within a few orbital periods. The majority of the mass transferred onto the black hole is accreted promptly; a significant fraction ({approx}30%) of the mass is shed outward as well, some of which will become gravitationally unbound and ejected completely from the system. The remaining portion forms an accretion disk around the black hole, and could provide the energy source for short-duration gamma-ray bursts.

• OSTI ID: 20795729
• Journal Information: Physical Review. D, Particles Fields, Vol. 73, Issue 2; Other Information: DOI: 10.1103/PhysRevD.73.024012; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ACCRETION DISKS
APPROXIMATIONS
BINARY STARS
BLACK HOLES
COMPUTERIZED SIMULATION
COSMIC GAMMA BURSTS
COSMOLOGY
EINSTEIN FIELD EQUATIONS
GENERAL RELATIVITY THEORY
HYDRODYNAMICS
LAGRANGIAN FUNCTION
MASS
MASS TRANSFER
MATHEMATICAL SOLUTIONS
NEUTRON STARS
RELATIVISTIC RANGE
SCHWARZSCHILD METRIC
SPACE-TIME