skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: General-relativistic decompression of binary neutron stars during dynamic inspiral

Abstract

We investigate the dynamic stability of inspiraling neutron stars by performing multiple-orbit numerical relativity simulations of the binary neutron star inspiral process. By introducing eccentricities in the orbits of the neutron stars, significant changes in orbital separation are obtained within orbital timescales. We find that as the binary system evolves from apastron to periastron (as the binary separation decreases), the central rest mass density of each star decreases, thus stabilizing the stars against individual prompt collapse. As the binary system evolves from periastron to apastron, the central rest mass density increases; the neutron stars recompress as the binary separation increases.

Authors:
 [1]
  1. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States)
Publication Date:
OSTI Identifier:
20933276
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 75; Journal Issue: 2; Other Information: DOI: 10.1103/PhysRevD.75.024001; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; NEUTRON STARS; ORBITS; RELATIVISTIC RANGE; REST MASS; SIMULATION

Citation Formats

Miller, Mark. General-relativistic decompression of binary neutron stars during dynamic inspiral. United States: N. p., 2007. Web. doi:10.1103/PHYSREVD.75.024001.
Miller, Mark. General-relativistic decompression of binary neutron stars during dynamic inspiral. United States. doi:10.1103/PHYSREVD.75.024001.
Miller, Mark. Mon . "General-relativistic decompression of binary neutron stars during dynamic inspiral". United States. doi:10.1103/PHYSREVD.75.024001.
@article{osti_20933276,
title = {General-relativistic decompression of binary neutron stars during dynamic inspiral},
author = {Miller, Mark},
abstractNote = {We investigate the dynamic stability of inspiraling neutron stars by performing multiple-orbit numerical relativity simulations of the binary neutron star inspiral process. By introducing eccentricities in the orbits of the neutron stars, significant changes in orbital separation are obtained within orbital timescales. We find that as the binary system evolves from apastron to periastron (as the binary separation decreases), the central rest mass density of each star decreases, thus stabilizing the stars against individual prompt collapse. As the binary system evolves from periastron to apastron, the central rest mass density increases; the neutron stars recompress as the binary separation increases.},
doi = {10.1103/PHYSREVD.75.024001},
journal = {Physical Review. D, Particles Fields},
number = 2,
volume = 75,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2007},
month = {Mon Jan 15 00:00:00 EST 2007}
}
  • The early part of the gravitational wave signal of binary neutron-star inspirals can potentially yield robust information on the nuclear equation of state. The influence of a star's internal structure on the waveform is characterized by a single parameter: the tidal deformability {lambda}, which measures the star's quadrupole deformation in response to the companion's perturbing tidal field. We calculate {lambda} for a wide range of equations of state and find that the value of {lambda} spans an order of magnitude for the range of equation of state models considered. An analysis of the feasibility of discriminating between neutron-star equations ofmore » state with gravitational wave observations of the early part of the inspiral reveals that the measurement error in {lambda} increases steeply with the total mass of the binary. Comparing the errors with the expected range of {lambda}, we find that Advanced LIGO observations of binaries at a distance of 100 Mpc will probe only unusually stiff equations of state, while the proposed Einstein Telescope is likely to see a clean tidal signature.« less
  • General relativistic simulations for the merger of binary neutron stars are performed as an extension of a previous work [M. Shibata and K. Taniguchi, Phys. Rev. D 73, 064027 (2006).]. We prepare binary neutron stars with a large initial orbital separation and employ the moving-puncture formulation, which enables one to follow merger and ringdown phases for a long time, even after black hole formation. For modeling inspiraling neutron stars, which should be composed of cold neutron stars, the Akmal-Pandharipande-Ravenhall (APR) equation of state (EOS) is adopted. After the onset of merger, the hybrid-type EOS is used; i.e., the cold andmore » thermal parts are given by the APR and {gamma}-law EOSs, respectively. Three equal-mass binaries, each with mass 1.4M{sub {center_dot}}, 1.45M{sub {center_dot}}, and 1.5M{sub {center_dot}}, and two unequal-mass binaries with mass, 1.3 vs 1.6M{sub {center_dot}} and 1.35 vs 1.65M{sub {center_dot}}, are prepared. We focus primarily on the black hole formation case, and explore mass and spin of the black hole, mass of disks which surround the black hole, and gravitational waves emitted during the black hole formation. We find that (i) the black hole is promptly formed if total mass of the system initially satisfies m{sub 0} > or approx. 2.9M{sub {center_dot}}; (ii) for the systems of m{sub 0}=2.9-3.0M{sub {center_dot}} and of mass ratio {approx_equal}0.8, the mass of disks which surround the formed black hole is 0.006-0.02M{sub {center_dot}}; (iii) the spin of the formed black hole is 0.78{+-}0.02 when a black hole is formed after the merger in the dynamical time scale. This value depends weakly on the total mass and mass ratio, and is about 0.1 larger than that of a black hole formed from nonspinning binary black holes; (iv) for the black hole formation case, Fourier spectrum shape of gravitational waves emitted in the merger and ringdown phases has a universal qualitative feature irrespective of the total mass and mass ratio, but quantitatively, the spectrum reflects the parameters of the binary neutron stars.« less
  • We study the transition from inspiral to plunge in general relativity by computing gravitational waveforms of nonspinning, equal-mass black-hole binaries. We consider three sequences of simulations, starting with a quasicircular inspiral completing 1.5, 2.3 and 9.6 orbits, respectively, prior to coalescence of the holes. For each sequence, the binding energy of the system is kept constant and the orbital angular momentum is progressively reduced, producing orbits of increasing eccentricity and eventually a head-on collision. We analyze in detail the radiation of energy and angular momentum in gravitational waves, the contribution of different multipolar components and the final spin of themore » remnant, comparing numerical predictions with the post-Newtonian approximation and with extrapolations of point-particle results. We find that the motion transitions from inspiral to plunge when the orbital angular momentum L=L{sub crit}{approx_equal}0.8M{sup 2}. For L<L{sub crit} the radiated energy drops very rapidly. Orbits with L{approx_equal}L{sub crit} produce our largest dimensionless Kerr parameter for the remnant, j=J/M{sup 2}{approx_equal}0.724{+-}0.13 (to be compared with the Kerr parameter j{approx_equal}0.69 resulting from quasicircular inspirals). This value is in good agreement with the value of 0.72 reported in [I. Hinder, B. Vaishnav, F. Herrmann, D. Shoemaker, and P. Laguna, Phys. Rev. D 77, 081502 (2008).]. These conclusions are quite insensitive to the initial separation of the holes, and they can be understood by extrapolating point-particle results. Generalizing a model recently proposed by Buonanno, Kidder and Lehner [A. Buonanno, L. E. Kidder, and L. Lehner, Phys. Rev. D 77, 026004 (2008).] to eccentric binaries, we conjecture that (1) j{approx_equal}0.724 is close to the maximal Kerr parameter that can be obtained by any merger of nonspinning holes, and (2) no binary merger (even if the binary members are extremal Kerr black holes with spins aligned to the orbital angular momentum, and the inspiral is highly eccentric) can violate the cosmic censorship conjecture.« less
  • We present the first fully relativistic calculations of the crustal strain induced in a neutron star by a binary companion at the late stages of inspiral, employing realistic equations of state for the fluid core and the solid crust. We show that while the deep crust is likely to fail only shortly before coalescence, there is a large variation in elastic strain, with the outermost layers failing relatively early on in the inspiral. We discuss the significance of the results for both electromagnetic and gravitational-wave astronomy.
  • In this Letter, we propose that a fast radio burst (FRB) could originate from the magnetic interaction between double neutron stars (NSs) during their final inspiral within the framework of a unipolar inductor model. In this model, an electromotive force is induced on one NS to accelerate electrons to an ultra-relativistic speed instantaneously. We show that coherent curvature radiation from these electrons moving along magnetic field lines in the magnetosphere of the other NS is responsible for the observed FRB signal, that is, the characteristic emission frequency, luminosity, duration, and event rate of FRBs can be well understood. In addition,more » we discuss several implications of this model, including double-peaked FRBs and possible associations of FRBs with short-duration gamma-ray bursts and gravitational-wave events.« less