arXiv subjects

Sifiso A. Ngubelanga

Publications and source records attributed to Sifiso A. Ngubelanga.

3 recordsLinked to original sources

arXiv2015

Relativistic stars with polytropic equation of state

We consider the Einstein-Maxwell system of equations in the context of isotropic coordinates for matter distributions with anisotropy in the presence of an electric field. We assume a polytropic equation of state for the matter configuration. New classes of exact solutions are generated for different polytropic indices. The model is well behaved and we can regain masses of several observed objects, in particular we obtain the mass of the star PSR J1903+327.

gr-qc↗

arXiv2015

Compact stars with quadratic equation of state

We provide new exact solutions to the Einstein-Maxwell system of equations for matter configurations with anisotropy and charge. The spacetime is static and spherically symmetric. A quadratic equation of state is utilised for the matter distribution. By specifying a particular form for one of the gravitational potentials and the electric field intensity we obtain new exact solutions in isotropic coordinates. In our general class of models, an earlier model with a linear equation of state is regained. For particular choices of parameters we regain the masses of the stars PSR J1614-2230, 4U 1608-52, PSR J1903+0327, EXO 1745-248 and SAX J1808.4-3658. A comprehensive physical analysis for the star PSR J1903+0327 reveals that our model is reasonable.

gr-qc↗

arXiv2015

Compact stars with linear equation of state in isotropic coordinates

We present a new class of spherically symmetric spacetimes for matter distributions with anisotropic pressures in the presence of an electric field. The equation of state for the matter distribution is linear. A class of new exact solutions is found to the Einstein-Maxwell system of equations with an isotropic form of the line element. We achieve this by specifying particular forms for one of the gravitational potentials and the electric field intensity. We regain the masses of the stars PSR J1614-2230, Vela X-1, PSR J1903+327, 4U 1820-30 and SAX J1808.4-3658 for particular parameter values. A detailed physical analysis for the star PSR J1614-2230 indicates that the model is well behaved.

gr-qc↗