Comment on “Gravitational Radiation Instability in Hot Young Neutron Stars”

Jones, P. B.

doi:10.1103/physrevlett.86.1384

Cited by 68 publications

(79 citation statements)

References 12 publications

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“…For example, it can drive a secular bar instability in rapidly rotating neutron stars, as shown in Newtonian gravitation [1,2] and in general relativity [3]. Viscosity can suppress the r-modes [4,5] and other gravitational-radiation driven instabilities, including the secular bar modes [6]. Viscosity also destroys differential rotation, and this can cause significant changes in the structure and evolution of differentially rotating massive neutron stars.…”

Section: Introductionmentioning

confidence: 99%

General relativistic hydrodynamics with viscosity: Contraction, catastrophic collapse, and disk formation in hypermassive neutron stars

et al. 2004

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Viscosity and magnetic fields drive differentially rotating stars toward uniform rotation, and this process has important consequences in many astrophysical contexts. For example, merging binary neutron stars can form a "hypermassive" remnant, i.e. a differentially rotating star with a mass greater than would be possible for a uniformly rotating star. The removal of the centrifugal support provided by differential rotation can lead to delayed collapse of the remnant to a black hole, accompanied by a delayed burst of gravitational radiation. Both magnetic fields and viscosity alter the structure of differentially rotating stars on secular timescales, and tracking this evolution presents a strenuous challenge to numerical hydrodynamic codes. Here, we present the first evolutions of rapidly rotating stars with shear viscosity in full general relativity. We self-consistently include viscosity in our relativistic hydrodynamic code by solving the fully relativistic Navier-Stokes equations. We perform these calculations both in axisymmetry and in full 3+1 dimensions. In axisymmetry, the resulting reduction in computational costs allows us to follow secular evolution with high resolution over dozens of rotation periods (thousands of M ). We find that viscosity operating in a hypermassive star generically leads to the formation of a compact, uniformly rotating core surrounded by a low-density disk. These uniformly rotating cores are often unstable to gravitational collapse. We follow the collapse in such cases and determine the mass and the spin of the final black hole and ambient disk. However, viscous braking of differential rotation in hypermassive neutron stars does not always lead to catastrophic collapse, especially when viscous heating is substantial. The stabilizing influences of viscous heating, which generates enhanced thermal pressure, and centrifugal support prevent collapse in some cases, at least until the star cools. In all cases studied, the rest mass of the resulting disk is found to be 10-20% of the original star, whether surrounding a uniformly rotating core or a rotating black hole. This study represents an important step toward understanding secular effects in relativistic stars and foreshadows more detailed, future simulations, including those involving magnetic fields.

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Section: Introductionmentioning

confidence: 99%

General relativistic hydrodynamics with viscosity: Contraction, catastrophic collapse, and disk formation in hypermassive neutron stars

et al. 2004

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“…Even if the initial field is weak, fluid motions produced by these oscillations may amplify the magnetic field and eventually distort or suppress the r-modes altogether. (R-modes may also be suppressed by non-linear mode coupling [23] or hyperon bulk viscosity [24]. )…”

Section: Introductionmentioning

confidence: 99%

Relativistic magnetohydrodynamics in dynamical spacetimes: Numerical methods and tests

et al. 2005

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Many problems at the forefront of theoretical astrophysics require the treatment of magnetized fluids in dynamical, strongly curved spacetimes. Such problems include the origin of gamma-ray bursts, magnetic braking of differential rotation in nascent neutron stars arising from stellar core collapse or binary neutron star merger, the formation of jets and magnetized disks around newborn black holes, etc. To model these phenomena, all of which involve both general relativity (GR) and magnetohydrodynamics (MHD), we have developed a GRMHD code capable of evolving MHD fluids in dynamical spacetimes. Our code solves the Einstein-Maxwell-MHD system of coupled equations in axisymmetry and in full 3+1 dimensions. We evolve the metric by integrating the BSSN equations, and use a conservative, shock-capturing scheme to evolve the MHD equations. Our code gives accurate results in standard MHD code-test problems, including magnetized shocks and magnetized Bondi flow. To test our code's ability to evolve the MHD equations in a dynamical spacetime, we study the perturbations of a homogeneous, magnetized fluid excited by a gravitational plane wave, and we find good agreement between the analytic and numerical solutions.

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“…We then obtain (after an approximate algebraic simplification) The third term arises from the bulk viscosity produced by out-of-equilibrium hyperon reactions (which dominate that produced by direct and modified Urca reactions). This has been studied by Jones (2001aJones ( , 2001b and Lindblom & Owen (2002) for normal nuclear matter and by Haensel, Levenfish, & Yakovlev (2002) for superfluids. We employ the results of Lindblom & Owen (2002) for .…”

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confidence: 99%

Conditions for Steady Gravitational Radiation from Accreting Neutron Stars

Wagoner

2002

The Astrophysical Journal

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The gravitational wave-and accretion-driven evolution of the angular velocity, core temperature, and (small) amplitude of an r-mode of neutron stars in low-mass X-ray binaries and similar systems is investigated. The conditions required for evolution to a stable equilibrium state (with gravitational wave flux proportional to average X-ray flux) are determined. In keeping with conclusions derived from observations of neutron star cooling, the core neutrons are taken to be normal while the core protons and hyperons and the crust neutrons are taken to be singlet superfluids. The dominant sources of damping are then hyperon bulk viscosity (if much of the core is at least 2-3 times nuclear density) and (e-e and n-n) shear (and possibly magnetic) viscosity within the corecrust boundary layer. It is found that a stable equilibrium state can be reached if the superfluid transition temperature of the hyperons is sufficiently small (Շ K), allowing the gravitational radiation from Sco X-1 and several 9 2 # 10 other neutron stars in low-mass X-ray binaries to be potentially detectable by the second-generation LIGO (and VIRGO) arrays.

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Comment on “Gravitational Radiation Instability in Hot Young Neutron Stars”

Cited by 68 publications

References 12 publications

General relativistic hydrodynamics with viscosity: Contraction, catastrophic collapse, and disk formation in hypermassive neutron stars

General relativistic hydrodynamics with viscosity: Contraction, catastrophic collapse, and disk formation in hypermassive neutron stars

Relativistic magnetohydrodynamics in dynamical spacetimes: Numerical methods and tests

Conditions for Steady Gravitational Radiation from Accreting Neutron Stars

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