Sensitivity of the neutron star<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>r</mml:mi></mml:math>-mode instability window to the density dependence of the nuclear symmetry energy

Wang, Dehua; Newton, William; Li, Bao-An

doi:10.1103/physrevc.85.025801

Cited by 62 publications

(81 citation statements)

References 52 publications

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“…A similar study has been recently done by Wen, Newton and Li in Ref. [45] using a simple model for the EoS that consistently describes the crust-core transition density. Assuming that the main dissipation mechanism of the r-modes is due to the electron-electron scattering at the crust-core boundary, and using the estimated core temperature of several low-mass X-ray binaries (LMXB), these authors conclude that neutron stars are stabilized against r-mode oscillations if L is smaller than ∼ 65 MeV.…”

Section: Introductionmentioning

confidence: 91%

Nuclear symmetry energy and ther-mode instability of neutron stars

Vidaña

2012

Phys. Rev. C

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We analyze the role of the symmetry energy slope parameter L on the r-mode instability of neutron stars. Our study is performed using both microscopic and phenomenological approaches of the nuclear equation of state. The microscopic ones include the Brueckner-Hartree-Fock approximation, the well known variational equation of state of Akmal, Pandharipande and Ravenhall, and a parametrization of recent Auxiliary Field Diffusion Monte Carlo calculations. For the phenomenological approaches, we use several Skyrme forces and relativisic mean field models. Our results show that the r-mode instability region is smaller for those models which give larger values of L. The reason is that both bulk (ξ ) and shear (η) viscosities increase with L and, therefore, the damping of the mode is more efficient for the models with larger L. We show also that the dependence of both viscosities on L can be described at each density by simple power-laws of the type ξ = A ξ L B ξ and η = A η L B η . Using the measured spin frequency and the estimated core temperature of the pulsar in the low-mass X-ray binary 4U 1608-52, we conclude that observational data seem to favor values of L larger than ∼ 50 MeV if this object is assumed to be outside the instability region, its radius is in the range 11.5 − 12(11.5 − 13) km, and its mass 1.4M ⊙ (2M ⊙ ). Outside this range it is not possible to draw any conclusion on L from this pulsar.

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Section: Introductionmentioning

confidence: 91%

Nuclear symmetry energy and ther-mode instability of neutron stars

Vidaña

2012

Phys. Rev. C

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“…[4][5][6]. Recently, appreciable progresses have been achieved on constraining the symmetry energy at saturation and subsaturation densities either through the extraction based on astrophysical observations or in terms of terrestrial data [7][8][9][10][11][12]. However, the density dependence of the symmetry energy is still poorly known at supranormal densities [3,[13][14][15].…”

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confidence: 99%

Symmetry energy softening in nuclear matter with non-nucleonic constituents

2013

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We study the trend of the nuclear symmetry energy in relativistic mean-field models with appearance of the hyperon and quark degrees of freedom at high densities. On the pure hadron level, we focus on the role of Λ hyperons in influencing the symmetry energy both at given fractions and at charge and chemical equilibriums. The softening of the nuclear symmetry energy is observed with the inclusion of the Λ hyperons that suppresses the nucleon fraction. In the phase with the admixture of quarks and hadrons, the equation of state is established on the Gibbs conditions. With the increase of the quark phase fraction in denser and denser matter, the apparent nuclear symmetry energy decreases till to disappear. This softening would have associations with the observations which need detailed discriminations in dense matter with the admixture of new degrees of freedom created by heavy-ion collisions.

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“…In what follows we will use the same approach as discussed in Ref. [111,112,113,114]. By assuming that the crust of the neutrons star is perfectly rigid, one can find an upper limit on the instability window.…”

Section: The R-mode Instability In Neutron Starsmentioning

confidence: 99%

“…In the realistic case of more elastic crust, the dissipation from the core-crust boundary decreases and therefore widens the instability window. In a recent work involving some of us [111], we studied the sensitivity of the r-mode instability to the density dependence of the symmetry energy. In particular, by employing a simple model of a neutron star with a perfectly rigid crust constructed with a set of crust and core EOS that span the range of nuclear experimental uncertainly in the symmetry energy, we found that EOSs characterized by the density slope L of smaller than 65 MeV are more consistent with the observed frequencies in LMXBs.…”

Section: The R-mode Instability In Neutron Starsmentioning

confidence: 99%

“…10 the timescales for the gravitational radiation (left window) and the shear viscosity (right window), which dissipates the r-mode instability are shown as a function of stellar mass. The stellar structure is modeled with a rigid crust [111] for the adopted EOSs, and the shear viscosity of the boundary layer is taken to be dominated by electron-electron scattering. Both timescales depend on the stellar mass with gravitational timescale being a decreasing function of the neutron star mass, whereas the viscous damping timescale is an increasing function of the stellar mass.…”

Section: The R-mode Instability In Neutron Starsmentioning

confidence: 99%

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Probing the high-density behavior of symmetry energy with gravitational waves

Fattoyev

Newton

2014

Eur. Phys. J. A

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Abstract. Gravitational wave (GW) astronomy opens up an entirely new window on the Universe to probe the equations of state (EOS) of neutron-rich matter. With the advent of next generation GW detectors, measuring the gravitational radiation from coalescing binary neutron star systems, mountains on rotating neutron stars, and stellar oscillation modes may become possible in the near future. Using a set of model EOSs satisfying the latest constraints from terrestrial nuclear experiments, state of the art nuclear manybody calculations of the pure neutron matter EOS, and astrophysical observations consistently, we study various GW signatures of the high-density behavior of the nuclear symmetry energy, which is considered among the most uncertain properties of dense neutron-rich nucleonic matter. In particular, we find the tidal polarizability of neutron stars, potentially measurable in binary systems just prior to merger, is more sensitive to the high density component of the nuclear symmetry energy than the symmetry energy at nuclear saturation density. We also find that the upper limit on the GW strain amplitude from elliptically deformed stars is very sensitive to the density dependence of the symmetry energy. This suggests that future developments in modeling of the neutron star crust, and direct gravitational wave signals from accreting binaries will provide a wealth of information on the EOS of neutron-rich matter. We also review the sensitivity of the r-mode instability window to the density dependence of the symmetry energy. Whereas models with larger values of the density slope of the symmetry energy at saturation seem to be disfavored by the current observational data, within a simple r-mode model, we point out that a subsequent softer behavior of the symmetry energy at high densities (hinted at by recent observational interpretations) could rule them in. PACS

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Sensitivity of the neutron starr-mode instability window to the density dependence of the nuclear symmetry energy

Cited by 62 publications

References 52 publications

Nuclear symmetry energy and ther-mode instability of neutron stars

Nuclear symmetry energy and ther-mode instability of neutron stars

Symmetry energy softening in nuclear matter with non-nucleonic constituents

Probing the high-density behavior of symmetry energy with gravitational waves

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