2023/07/05 by Sengupta, Rikpratik, Chanda, Anirban, Paul, B C +1
#FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc)
paper · doi:10.48550/arxiv.2307.02602
In this paper, we attempt to explore the possibility of a obtaining a viable emergent universe scenario supported by a type of fluid known as the extended Chaplygin gas, which extends a modification to the equation of state of the well known modified Chaplygin gas by considering additional higher order barotropic fluid terms. We consider quadratic modification only. Such a fluid is capable of explaining the present cosmic acceleration and is a possible dark energy candidate. We construct a theoretical model of the emergent universe assuming it is dominated by such a fluid at late times. Our model results in non-conventional late-time behavior and deviates from the standard Λ-CDM model. Dark energy is found to cross the phantom divide in the past and present besides exhibiting thawing behaviour in the future, asymptotically leading to transition into a decelerating phase making dark energy a transient phenomenon. The qualitative nature of variation of the cosmological parameters resulting from model parameters observationally constrained through Markov Chain Monte Carlo sampling of Pantheon+OHD data is interestingly found to resemble the DESI results. Also,the value of H(z) at a redshift z=2.34 and present value of Hubble parameter fits much better than Λ-CDM with recent observations. This leads us to the realization that such a fluid is not only a probable candidate for dark energy, but also sources an emergent universe unlike modified Chaplygin gas and the initial singularity problem can be resolved in a flat universe within the standard relativistic context.