We construct some cosmological models in an extended gravity theory. The gravitational action of the extended gravity theory contains a term proportional to the trace of the energy momentum tensor in addition to the usual Ricci scalar. Keeping in view the cosmic transit behavior from a decelerated universe to an accelerated one, we have employed a hybrid scale factor (HSF) to study the cosmic...

We investigate the thermodynamic properties of strange quark matter under the strong magnetic field in the framework of the MIT bag model with the density-dependent bag constant. We consider two cases of the magnetic field, the uniform magnetic fields, and the density-dependent magnetic field to calculate the equation of state of strange quark matter. For the density-dependent magnetic field...

The structural properties of neutron stars, namely, maximum mass is a subject that theoretical astrophysicists have desired to study. Theoretically, investigation of structure for neutron stars necessities obtaining the perfect hydrostatic equilibrium equations. Up to now, different models and metrics have been used to calculate these equations. It is expected higher order energy-momentum...

In this work, we review the formalism which would allow us to model magnetically deformed neutron stars. We study the effect of different magnetic field configurations on the equation of state (EoS) and structure of such stars. In this study, the EoS of magnetars is acquired by using the lowest order constraint variational (LOCV) method and the upper limit of the magnetic field is derived...

The influence of a spherical boundary on the vacuum fluctuations of a massive scalar field is investigated in background of $\left( D+1\right) $-dimensional Milne universe, assuming that the field obeys Robin boundary condition on the sphere. The normalized mode functions are derived for the regions inside and outside the sphere. For the interior region, the boundary-induced contribution is...

In this work we use the dynamical system approach to study the stability of a normal DGP model in which we assume that a tachyon scalar field plays the role of dark energy. We consider an exponential potential ($V_0e^{\alpha\phi}$) for the tachyon field. We write the main equations of the model. Then, with attention to these equations, we introduce a set of new dimensionless dynamical...