Stability ofβ-equilibrated dense matter and core-crust transition in neutron stars

Abstract

The stability of the β-equilibrated dense nuclear matter is analyzed with respect to the thermodynamic stability conditions. Based on the density dependent M3Y effective nucleon-nucleon interaction, the effects of the nuclear incompressibility on the proton fraction in neutron stars and the location of the inner edge of their crusts and core-crust transition density and pressure are investigated. The high-density behavior of symmetric and asymmetric nuclear matter satisfies the constraints from the observed flow data of heavy-ion collisions. The neutron star properties studied using β-equilibrated neutron star matter obtained from this effective interaction for a pure hadronic model agree with the recent observations of the massive compact stars. The density, pressure and proton fraction at the inner edge separating the liquid core from the solid crust of neutron stars are determined to be ρt = 0.0938 fm −3 , Pt = 0.5006 MeV fm −3 and x p(t) = 0.0308, respectively.

Nuclear constraints on the core-crust transition and crustal fraction of moment of inertia of neutron stars

“…In the present work, the equation of state (EoS) used is obtained from the density dependent M3Y effective nucleon-nucleon interaction (DDM3Y) for which the incompressibility K ∞ for the symmetric nuclear matter (SNM), nuclear symmetry energy E sym (ρ 0 ) at saturation density ρ 0 , the isospin dependent part K τ of the isobaric incompressibility and the slope L are in excellent agreement with the constraints recently extracted from measured isotopic dependence of the giant monopole resonances in even-A Sn isotopes, from the neutron skin thickness of nuclei, and from analyses of experimental data on isospin diffusion and isotopic scaling in intermediate energy heavy-ion collisions [8,9]. The core-crust transition in neutron stars is determined [10] by analyzing the stability of the β-equilibrated dense nuclear matter with respect to the thermodynamic stability conditions [11][12][13][14][15]. The mass-radius relation for neutron stars is obtained by solving the Tolman-Oppenheimer-Volkoff Equation (TOV) [16,17] and then the crustal fraction of moment of inertia is determined using pressure and density at core-crust transition.…”

Gravitational waves from isolated neutron stars: Mass dependence of r -mode instability

“…The stability of the β-equilibrated dense matter in neutron stars is investigated and the location of the inner edge of their crusts and core-crust transition density and pressure are determined using the DDM3Y ef-fective nucleon-nucleon interaction [67]. The stability of any single phase, also called intrinsic stability, is ensured by the convexity of ǫ(ρ, x p ).…”

Mass-Radius Relationship of Neutron Stars Admixed with Fermionic Asymmetric Dark Matter

“…Using the usual values of α=0.005 MeV −1 for the parameter of energy dependence of the zero range potential and n=2/3, the values obtained for the constants of density dependence C and β and the SNM incompressibility K ∞ are 2.2497, 1.5934 fm 2 and 274.7 MeV, respectively. The saturation energy per nucleon is the volume energy coefficient and the value of -15.26±0.52 MeV covers, more or less, the entire range of values obtained for a v for which now the values of C=2.2497±0.0420, β=1.5934±0.0085 fm 2 and the SNM incompressibility K ∞ =274.7±7.4 MeV [8,9].…”