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arXiv · 1806.07246

Non-singular model universe from a perfect fluid scalar-metric cosmology

Mohsen Khodadi·Kourosh Nozari
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Abstract

To seek for a singularity free model universe from a perfect fluid scalar-metric cosmology, we work in the "\emph{Emergent Cosmology}" (EC) paradigm which is a non-singular alternative for cosmological inflation. By using two methods including Linear Stability Theory and Effective Potential Formalism, we perform a classical analysis on the possible static solutions (that are called usually as Einstein Static Universes (ESU)in literature) in order to study EC paradigm in a FRW background. Our model contains a kinetic term of the scalar field minimally coupled to the background geometry without a potential term. The matter content of the model consists of a perfect fluid plus a cosmological constant $\Lambda$ as a separate source. In the framework of a local dynamical system analysis, we show that in the absence or presence of $\Lambda$, depending on some adopted values for the free parameters of the underlying cosmological model with flat and non-flat spatial geometries, one gets some static solutions which are viable under classical linear perturbations. By extending our study to a global dynamical system analysis, we show that in the presence of $\Lambda$ with non-flat spatial geometries there is a future global de Sitter attractor in this model. Following the second method, we derive a new static solution that represents a stable ESU but this time without dependence on the free parameters of the cosmological model at hand. As a whole, our analysis suggests the possibility of graceful realization of a non-singular EC paradigm (i.e. leaving the initial static phase and entering the inflation period as the universe is evolving) through either preserving or violation of the strong energy condition.

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Mohsen Khodadi, Kourosh Nozari. 2018-06-16. Non-singular model universe from a perfect fluid scalar-metric cosmology. https://doi.org/10.1007/s10714-018-2405-1

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