ANALYSIS OF THE EQUATIONS OF STATE FOR NEUTRON STARS

Аннотация

In this work we consider various equations of state of neutron star matter, which include from the
point of neutron drops formation to supra nuclear densities. Particular attention is paid to the nucleon – nucleon
interaction since, in addition to the kinetic energies of the particles, the interactions among nucleons play a key role.
Moreover, we investigate the properties of super-dense matter with diverse sets of particles such as electrons,
protons, and the contribution of various particles-carriers of interaction. In order to achieve these goals, different
potentials were considered, which are in a good agreement with experimental data. Furthermore, we find the energy
of the system by using a variety of multi-particle methods, including the interaction of nucleons. Thanks to this
information, thermodynamic parameters such as pressure, energy density and the speed of sound in the star are
calculated. We compared similar equations of state of matter so that we could demonstrate the difference from each
other. The Tolman-Oppenheimer-Volkoff system of equations has been solved numerically to construct mass-central
density, radius-central density and mass-radius relations using different equations of state. In conclusion, the latest
observational constraints on the equation of state are taken into account and we show that the observational data
require that the equation of state be stiff, despite the fact that all stiff equations of state violate the principle of
causality at high central densities, unlike soft ones.