A Study on the Various Aspects of Bounce Realisation for Some Choices of Scale Factors

• Published in: Symmetry (Basel) Vol. 15; no. 7; p. 1332
• Main Authors: Saha, Sanghati, Güdekli, Ertan, Chattopadhyay, Surajit
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01-07-2023
• Subjects: bounce cosmology; Bouncing; bulk viscosity; Chaplygin gas; Cosmology; Dark energy; Dark matter; Einstein, Albert; Generelized Chaplygin gas; scale factor; Series expansion; String theory; Symmetry; Theory of relativity; Viscosity
• ISSN: 2073-8994; 2073-8994
• DOI: 10.3390/sym15071332

The current study examines the realisation of cosmic bounce in two situations involving two distinct scale factor selections, one of which is a scale factor already developed for bouncing and the other of which is a scale factor created by truncating a series expansion of a de Sitter scale factor. Generalized Chaplygin gas (GCG) is assumed to be the background fluid in both situations. When the scale factor is set to the first kind, the pre-bounce scenario’s GCG energy density decreases due to contraction, reaches its lowest point at t=0 during the bounce, and then rises as a result of expansion following the bounce. However, it is noted that the truncation has an impact on the density evolution from pre-bounce in the other scale factor scenario. The influence of bulk viscosity is shown in all circumstances, in addition to the influence of non-viscosity, and the test for stability makes use of the squared speed of sound. At the turn-around places, the null energy criterion is also violated. The final stage of the study includes a cosmographic analysis and a demonstration of the Hubble flow dynamics. In conclusion, we find that inflationary cosmology can also be realized with GCG as the background fluid for two-scale factor options. When the equivalent cosmic parameter is examined for pre-bounce and post-bounce scenarios, a symmetry is frequently seen. The symmetry occurs near the point of bouncing or turning.