Neutron star properties and the equation of state of neutron-rich matter

Abstract

We calculate total masses and radii of neutron stars (NS) for pure neutron matter and nuclear matter in β-equilibrium. We apply a relativistic nuclear matter equation of state (EOS) derived from Dirac-Brueckner-Hartree-Fock (DBHF) calculations. We use realistic nucleon-nucleon (NN) interactions defined in the framework of the meson exchange potential models. Our results are compared with other theoretical predictions and recent observational data. Suggestions for further study are discussed.

Properties of dense, asymmetric nuclear matter in Dirac-Brueckner-Hartree-Fock approach

“…[8] is very close to the present one up to high densities. Table I Because various results for nuclear matter given by the DBHF calculation have been reported elsewhere [4][5][6][7][8][9][10][11], we focus here on two topics: (i) the validity of the angle-averaged approximation and the averaging of the total momentum squared of the interacting two nucleons in matter and (ii) parametrizations for the nucleon self-energies and the EoS's for symmetric nuclear matter and pure neutron matter.…”

“…So far, in the DBHF calculation, the EoS for neutron-star matter is calculated by using the parabolic interpolation between the EoS for symmetric nuclear matter and the EoS for pure neutron matter (see, for example, Refs. [10,11]). However, in the present work, we 035805-4 calculate the EoS for asymmetric nuclear matter without such interpolations.…”

“…) However, before concluding that the EoS including hyperons cannot explain heavy neutron stars, it is very important to study the effect of in-medium two-nucleon correlations, which depends on the nuclear density, n B , on the EoS for the core matter. In this paper, we calculate the properties of dense, asymmetric nuclear matter using the Dirac-BruecknerHartree-Fock (DBHF) approach [4][5][6][7][8][9][10][11], which allows us to handle two vital ingredients: short-range correlations in nucleon-nucleon (NN) force, which are not included in MFT, and relativistic many-body effects.…”

Further explorations of Skyrme-Hartree-Fock-Bogoliubov mass formulas. XII. Stiffness and stability of neutron-star matter

“…The reason why the realistic calculations of the symmetry energy show almost as large a high-density divergence as our phenomenological forces lies at least partially with the choice of three-nucleon force and its behavior at high densities. Dirac-Brueckner-Hartree-Fock calculations, in which there is no three-nucleon force, also show a high-density softening of the EOS [37].…”

Nuclear symmetry energy and proton-rich reactions at intermediate energies

“…Many microscopic and/or phenomenological many-body theories using various interactions [16,17] predict that the symmetry energy increases continuously at all densities. However, other models [7,[18][19][20][21][22][23][24][25][26][27][28][29][30] predict that the symmetry energy first increases to a maximum and then may start decreasing at certain suprasaturation densities. Thus, currently the theoretical predictions on the symmetry energy at suprasaturation densities are extremely diverse.…”