Accelerated Expansion of the Universe in the Model with Nonuniform Pressure

Abstract

We present the particular case of the Stephani solution for shear-free perfect fluid with uniform energy density and non-uniform pressure. Such models appeared as possible alternative to the consideration of the exotic forms of matter like dark energy that would cause the acceleration of the universe expansion. These models are characterised by the spatial curvature depending on time. We analyze the properties of the cosmological model obtained on the basis of exact solution of the Stephani class and adopt it to the recent observational data. The spatial geometry of the model is investigated. We show that despite possible singularities, the model can describe the current stage of the universe evolution.

Hyperbolically Symmetric Versions of Lemaitre–Tolman–Bondi Spacetimes

“…Finally, we would like to conclude with a general comment: all the models exhibited above were found with the sole purpose of illustrating the richness of solutions endowed with hyperbolic symmetry and sharing the general physical and geometrical properties (excluding the isometry group) characterizing the LTB spacetimes. It is now up to cosmologists and astrophysicists to decide if any of the above models (or any other HSLTB not described in this manuscript) could be of any use in the study of specific scenarios, as for example cosmological models beyond the standard FRW solution [ 54 , 55 ].…”

Quasi-homologous evolution of self-gravitating systems with vanishing complexity factor

“…Indeed, for this latter case, the homol-ogous condition implies Y T F = 0 and produces the simplest configuration (Friedman-Robertson-Walker), which is the only one evolving homologously and satisfying Y T F = 0. Therefore our approach which implies a relaxing of the homologous condition, could lead to more sophisticated models of the Universe, as for example the one described in [84].…”

Geodesic Structure of the Accelerated Stephani Universe

“…Recently, a particular case of the Stephani solution was investigated as a possible model of the accelerated universe [16]. It was shown that the theoretical prediction for the redshift-magnitude relation in the model is in good accordance with type Ia Supernovae data.…”

“…In this paper, we investigate the geodesic structure of the model obtained in [16] to verify if the singularities of the model can affect the light and test particle motion within the observable area.…”