A dark energy model alternative to generalized Chaplygin gas

TL;DR

This paper introduces a new dark energy fluid model as an alternative to generalized Chaplygin gas, which predicts a future deceleration of cosmic expansion, differing from the eternal acceleration in standard models.

Contribution

It proposes a tachyon field-based dark energy model with a unique scalar potential, explaining late-time acceleration and future deceleration.

Findings

Dark energy density is suppressed during matter-dominated epochs.

The model predicts cosmic acceleration will eventually cease.

The universe will transition back to decelerated expansion.

Abstract

We propose a new fluid model of dark energy for $-1 \leq \omega_{\text{eff}} \leq 0$ as an alternative to the generalized Chaplygin gas models. The energy density of dark energy fluid is severely suppressed during barotropic matter dominant epochs, and it dominates the universe evolution only for eras of small redshift. From the perspective of fundamental physics, the fluid is a tachyon field with a scalar potential flatter than that of power-law decelerated expansion. Different from the standard $\Lambda\text{CDM}$ model, the suggested dark energy model claims that the cosmic acceleration at present epoch can not continue forever but will cease in the near future and a decelerated cosmic expansion will recover afterwards.