Accelerated Universe from Modified Chaplygin Gas and Tachyonic Fluid

TL;DR

This paper explores a cosmological model with a modified Chaplygin gas that can explain the universe's accelerated expansion, connecting it to scalar and tachyonic fields, and deriving their potentials.

Contribution

It introduces a novel mapping of the modified Chaplygin gas to scalar and tachyonic fields, providing new insights into dark energy modeling.

Findings

The modified Chaplygin gas can describe accelerated cosmic expansion.

A scalar field potential corresponding to the exotic fluid is derived.

A mapping between the fluid, scalar field, and tachyonic field is established.

Abstract

A cosmological model with an exotic fluid is investigated. We show that the equation of state of this ``modified Chaplygin'' gas can describe the current accelerated expansion of the universe. We then reexpress it as FRW cosmological model containing a scalar field $\phi$ and find its self--interacting potential. Moreover motivated by recent works of Sen [sen1, sen2] and Padmanbhan [pad] on tachyon field theory, a map for this exotic fluid as a normal scalar field $\phi$ with Lagrangian ${\cal L}_{\phi} = \frac{\dot{\phi}^2}{2} - U (\phi)$ to the tachyonic field $T$ with Lagrangian ${\cal L}_{T} = - V(T) \sqrt{1 - \dot{T}^2}$ is obtained.