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Kourosh Nozari

Kourosh Nozari

Academic rank: Professor
ORCID: https://orcid.org/0000-0003-4368-5823
Education: PhD.
ScopusId: 9276301800
Faculty: Science
Address: Department of Theoretical Physics, Faculty of Basic Sciences, University of Mazandaran, P. O. Box 47416-95447, Babolsar, Iran
Phone: 01135302482

Research

Title
Non-singular model universe from a perfect fluid scalar-metric cosmology
Type
JournalPaper
Keywords
Emergent Cosmology, Einstein Static Universe
Year
2018
Journal GENERAL RELATIVITY AND GRAVITATION
DOI
Researchers Mohsen Khodadi ، Kourosh Nozari

Abstract

To seek for a singularity freemodel universe from a perfect fluid scalar-metric cosmology, we work in the “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  as a separate source. In the framework of a local dynamical system analysis, we show that in the absence or presence of , 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  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.