Saturation properties of isospin asymmetric nuclear matter

The parabolic approximation to the equation of state of the isospin asymmetric nuclear matter (ANM) is widely used in the literature to make predictions for the nuclear structure and the neutron star properties. Based on the realistic M3Y-Paris and M3Y-Reid nucleon-nucleon interactions, we investigate the effects of the higher-order symmetry energy on the proton fraction in neutron stars and the location of the inner edge of their crusts and their core-crust transition density and pressure, thermodynamically. Analytical expressions for different-order symmetry energy coefficients of ANM are derived using the realistic interactions mentioned above. It is found that the higher-order terms of the symmetry energy coefficients up to its eighth-order ( ) contributes substantially to the proton fraction in stable neutron star matter at different nuclear matter densities, the core-crust transition density and pressure. Even by considering the symmetry energy coefficients up to , we obtain a significant change of about 40% in the transition pressure value from the one based on the exact equation of state. Using equations of state based on both Paris and Reid effective interactions which provide saturation incompressibility of symmetric nuclear matter in the range of 220 ≤ 0 ≤ 270 , we estimate the ranges 0.090 −3 ≤ ≤ 0.095 −3 and 0.49 −3 ≤ ≤ 0.59 −3 for the liquid coresolid crust transition density and pressure, respectively. The corresponding range of the proton fraction at this transition density range is found to be 0.029 ≤ ( ) ≤ 0.032.

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“…According to Eqs. (1) and (2), the different symmetry energy coefficients are given as [4], (1) 10 (7) , 00(10) ≡ 0(1) ( = 0), and 00 (10) ( )…”

Section: Theoretical Framework I Eos Of Isospin Asymmetric Nuclementioning

confidence: 99%

Higher-order symmetry energy of nuclear matter and the inner edge of neutron star crusts

Seif

Basu

2014

Phys. Rev. C

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“…Most works are restricted to spherical nuclei. The accurate investigation of the nuclear density distributions is of special importance to explore the saturation properties of asymmetric nuclear matter and its equation of state [5]. On the other hand, the clear correlation between the finite surface diffuseness and the number of surface nucleons influences the surface and the outer region of the nucleus-nucleus interaction potential [6] as well as the clustering of the individual entities on the nuclear surface.…”

Section: Introductionmentioning

confidence: 99%

Systematics of nucleon density distributions and neutron skin of nuclei

Seif

Mansour

2015

Int. J. Mod. Phys. E

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Proton and neutron density profiles of 760 nuclei in the mass region of are analyzed using the Skyrme energy density for the parameter set SLy4. Simple formulae are obtained to fit the resulting radii and diffuseness data. These formulae are useful to estimate the values of the unmeasured radii, and especially in extrapolating charge radii values for nuclei which are far from the valley of stability or to perform analytic calculations for bound and/or scattering problems. The obtained neutron and proton root-mean-square radii and the neutron skin thicknesses are in agreement with the available experimental data and previous Hartree-Fock calculations.

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“…There have been many efforts in parametrizations of the symmetry energy coefficients [8,[19][20][21][22][23][24][25][26][27][28][29]. Most of these efforts focused on the quadratic I 2 term [I = (N − Z)/A, called isospin asymmetry] of the symmetry energy.…”

mentioning

confidence: 99%

“…Indeed, studies of the EOS up to moderate densities suggest that the I 2 term plays a dominant role [4]. In the literature, one usually calls I 2 term the symmetry energy [24]. One would ask whether or not there exists sizable contribution from the higher order terms in addition to the I 2 term in symmetry energy.…”

mentioning

confidence: 99%

“…For instance, the recent nonlinear relativistic mean field model calculations [25] suggested that on the one hand the value of the I 4 term at the saturation density is less than 1 MeV and on the other hand the contribution of this term might be important at high densities. The recent nonrelativistic Hartree-Fock calculations [24] suggested that the higher order terms up to its eighth order contribute substantially to the proton fraction in βstable neutron star matter at different nuclear matter densities (see also Ref. [27]).…”

mentioning

confidence: 99%

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