A. Tlemissov, Al-Farabi Kazakh National University, Almaty 050040, Kazakhstan, master student, 0003-3453-3465,, Zh. Tlemissova, K. Boshkayev, A. Urazalina, H. Quevedo, Al-Farabi Kazakh National University, National Nanotechnology Laboratory of Open Type Almaty 050040, Kazakhstan, lecturer, ORCID ID,, Al-Farabi Kazakh National University, Almaty 050040, Kazakhstan, associate professor,,, Al-Farabi Kazakh National University, Almaty 050040, Kazakhstan, assistant professor, ,, Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, AP 70543, Mexico City 04510, Mexico, full professor,,
2020 Izvestiâ Nacionalʹnoj akademii nauk Respubliki Kazahstan. Seriâ fiziko-matematičeskaâ  
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
more » ... arriers 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.
doi:10.32014/2020.2518-1726.81 fatcat:njjf5o62bncudlq74stxeyw2xe