FRW type of cosmology with a Chaplygin gas

TL;DR

This paper investigates a cosmological model combining generalized Chaplygin gas and matter within a Robertson-Walker universe, revealing possible bouncing behaviors, phase transitions, and conditions for structure formation.

Contribution

It introduces a cosmological model with Chaplygin gas that can interpolate different universe phases and exhibits bouncing solutions depending on model parameters.

Findings

Universe can transition between radiation, matter, and cosmological constant dominance.

Bouncing universe solutions are possible with parameter changes.

Sound velocity may become imaginary, indicating potential structure formation.

Abstract

The evolution of a universe modelled as a mixture of generalised Chaplygin gas and ordinary matter field is studied for a Robertson Walker type of spacetime. This model could interpolate periods of a radiation dominated, matter dominated and a cosmological constant dominated universe. Depending on the arbitrary constants appearing in our theory the instant of flip changes. Interestingly we also get a bouncing model when the signature of one of the constants changes. The velocity of sound may become imaginary under certain situations pointing to a perturbative state and consequently the possibility of structure formation. We also discuss the whole situation in the backdrop of wellknown Raychaudhury equation and a comparison is made with the previous results.