Abstract
The emergent universe scenario is a proposal for resolving the Big Bang singularity problem in the standard Friedmann–Lemaitre–Robertson–Walker cosmology. In the context of this scenario, the Universe originates from a nonsingular static state. In the present work, considering the realization of the emergent universe scenario, we address the possibility of having a nonsingular Kantowski–Sachs type static state. Considering four and five dimensional models (with and without brane), it is shown that both the existence and stability of a nonsingular state depend on the dimensions of the spacetime and the nature of the fluid supporting the geometry.
Highlights
One interesting question that can be raised here is: can a non-FLRW static state be a seed for an emergent universe? To answer this question, one may consider Kantowski–Sachs (KS) [33] or Bianchi type cosmological models [34,35] and investigate their stability versus various perturbations
In [40], KS models are examined versus the classical tests of cosmology, and the results have been compared with those belonging to FLRW spacetime in the standard model of cosmology
It is discussed that the existence and stability of the nonsingular Kantowski–Sachs static state (KSSS) depend on the dimensions of the spacetime and the nature of the fluid supporting the geometry
Summary
The emergent universe scenario has been analyzed in Einstein’s GR and modified theories only for the FLRW spacetime. One may consider Kantowski–Sachs (KS) [33] or Bianchi type cosmological models [34,35] and investigate their stability versus various perturbations. KS models are spatially homogeneous and rotation-free but possess shear KS type anisotropic cosmological models are classified in the presence of a nonzero cosmological constant. It is shown that for a positive cosmological constant there exists a set of big bang models of zero measure as well as a set of models possessing nonzero measure with the de Sitter asymptotic. In [38], nonsingular KS type cosmological solutions are obtained in a quantum-corrected Einstein gravity. We obtain the existence and stability conditions versus the scalar perturbations for a Kantowski–Sachs static state (KSSS) for various energy–momentum sources with generic linear and Chaplygin gas type equations of state.
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