Elastic properties of polycrystalline dense matter

Kobyakov, Dmitry; Pethick, C. J.

doi:10.1093/mnrasl/slv027

Cited by 34 publications

(40 citation statements)

References 22 publications

(23 reference statements)

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“…For strain |ǫ| 0.04 the stress-strain curve for the polycrystalline MD simulation inFig. 1ofHorowitz & Kadau (2009) agrees well with the results ofOgata & Ichimaru (1990), but not with those ofKobyakov & Pethick (2015). However, this can be a specific property of this particular polycrystal.…”

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confidence: 50%

Breaking properties of neutron star crust

Baiko

Chugunov

2018

Monthly Notices of the Royal Astronomical Society

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The strength of neutron star crust is crucial for modelling magnetar flares, pulsar glitches and gravitational wave emission. We aim to shed some light on this problem by analysing uniaxial stretch deformation (elongation and contraction) of perfect bodycentered cubic Coulomb crystals, paying special attention to the inherent anisotropy of this process. Our analysis is based on the semi-analytical approach of Baiko & Kozhberov (2017), which, for any uniform deformation, allows one to calculate, in fully non-linear regime, critical deformation parameters beyond which the lattice loses its dynamic stability. We determine critical strain, pressure anisotropy and deformation energy for any stretch direction with respect to the crystallographic axes. These quantities are shown to be strongly anisotropic: they vary by a factor of almost 10 depending on the orientation of the deformation axis. For polycrystalline crust, we argue that the maximum strain for the stretch deformation sustainable elastically is 0.04. It is lower than the breaking strain of 0.1 obtained in molecular dynamic simulations of a shear deformation by Horowitz & Kadau (2009). The maximum pressure anisotropy of polycrystalline matter is estimated to be in the range from 0.005 to 0.014 nZ 2 e 2 /a, where n is the ion number density, Ze is the ion charge, and a is the ion-sphere radius. We discuss possible mechanisms of plastic motion and formation of large crystallites in neutron star crust as well as analyse energy release associated with breaking of such crystallites in the context of magnetic field evolution and magnetar flaring activity.

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confidence: 50%

Breaking properties of neutron star crust

Baiko

Chugunov

2018

Monthly Notices of the Royal Astronomical Society

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“…In any case, it is obvious from Fig. 5 that the location of the stars, inside or outside the instability window, depends strongly on the value of the factor S. In view of the above discussion, it is concluded that the study of the elastic properties of the crust is a very important issue in neutron star physics (for a recent study see [33]). To clarify further this statement, we display in Fig.…”

Section: /4mentioning

confidence: 87%

R-mode constraints from neutron star equation of state

Papazoglou

Moustakidis

2016

Astrophys Space Sci

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The gravitational radiation has been proposed a long time before, as an explanation for the observed relatively low spin frequencies of young neutron stars and of accreting neutron stars in low-mass X-ray binaries as well. In the present work we studied the effects of the neutron star equation of state on the r-mode instability window of rotating neutron stars. Firstly, we employed a set of analytical solution of the Tolman-Oppemheimer-Volkoff equations with special emphasis on the Tolman VII solution. In particular, we tried to clarify the effects of the bulk neutron star properties (mass, radius, density distribution, crust size and elasticity) on the r-mode instability window. We found that the critical angular velocity Ω c depends mainly on the neutron star radius. The effects of the gravitational mass and the mass distribution are almost negligible. Secondly, we studied the effect of the elasticity of the crust, via to the slippage factor S and also the effect of the nuclear equation of state, via the slope parameter L, on the instability window. We found that the crust effects are more pronounced, compared to those originated from the equation of state. Moreover, we proposed simple analytical expressions which relate the macroscopic quantity Ω c to the radius, the parameter L and the factor S. We also investigated the possibility to measure the radius of a neutron star and the factor S with the help of accurate measures of Ω c and the neutron star temperature. Finally, we studied the effects of the mutual friction on the instability window and discussed the results in comparison with previous similar studies.

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“…Recently, this shear modulus has been modified by taking into account the effect of electron screening (Kobyakov & Pethick 2013) and the effect of polycrystalline nature (Kobyakov & Pethick 2015). In this study, however, we adopt the traditional formula given by Eq.…”

Section: Shear Modulusmentioning

confidence: 99%

Astrophysical implications of double-layer torsional oscillations in a neutron star crust as a lasagna sandwich

Sotani

Iida

Oyamatsu

2019

Monthly Notices of the Royal Astronomical Society

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In the crust of a neutron star, global torsional oscillations could occur in two elastic layers. The outer and inner layers are composed of spherical and cylindrical nuclei and of cylindrical holes (tubes) and spherical holes (bubbles), respectively, while between these two layers, a phase of slab-like (lasagna) nuclei with vanishingly small elasticity is sandwiched. In this work, we update systematic calculations of the eigenfrequencies of the fundamental oscillations in the inner layer by newly allowing for the presence of tubes. We find that the frequencies still depend strongly on the slope parameter of the nuclear symmetry energy, L, while being almost independent of the incompressibility of symmetric nuclear matter. We also find that the fundamental frequencies in the inner layer can become smaller than those in the outer layer because the tube phase has a relatively small shear modulus and at the same time dominates the inner layer in thickness. As a result, we can successfully explain not only the quasi-periodic oscillations originally discovered in the observed X-ray afterglow of the giant flare of SGR 1806-20 but also many others recently found by a Bayesian procedure.

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Elastic properties of polycrystalline dense matter

Cited by 34 publications

References 22 publications

Breaking properties of neutron star crust

Breaking properties of neutron star crust

R-mode constraints from neutron star equation of state

Astrophysical implications of double-layer torsional oscillations in a neutron star crust as a lasagna sandwich

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