Ghost scalar field in neutron star

Abstract

The model of a neutron star containing a ghost scalar field is considered. The neutron fluid is modelled by a realistic Sly equation of state applicable for a description of matter at large energies and pressures typical for central regions of neutron stars. Two forms of the scalar field (massless and with a potential energy) are considered, for which the cases with trivial and nontrivial spacetime wormhole-like topologies are studied. The system of ordinary differential equations describing the distribution of the neutron fluid, gravitational and scalar fields is derived. By solving this system numerically, we demonstrate the influence of the presence of the ghost scalar field on the mass-radius relation of neutron stars and their internal structure. It is shown that the distribution of the total density of the configurations under consideration changes substantively depending on the properties of the scalar field. The values of free parameters of the system, for which one can obtain the best agreement of the model with the current observational astronomical data, are determined.