Big brake singularity is accommodated as an exotic quintessence field

TL;DR

This paper models a big brake singularity using an exotic quintessence field derived from a modified Chaplygin gas, analyzing its stability and perturbation behavior near the singularity.

Contribution

It introduces a novel exotic quintessence model for big brake singularity and examines its stability and perturbations at the background and linear levels.

Findings

Exotic field remains finite at the singularity while kinetic and potential energies diverge.

Perturbed pressure and contrast density diverge for positive alpha, but the exotic field perturbation vanishes exponentially.

Contrast density always diverges for negative alpha, while the field perturbation remains bounded.

Abstract

We describe a big brake singularity in terms of a modified Chaplygin gas equation of state $p=(\ga_{m}-1)\rho+\al\ga_{m}\rho^{-n}$, accommodate this late-time event as an exotic quintessence model obtained from an energy-momentum tensor, and focus on the cosmological behavior of the exotic field, its kinetic energy and the potential energy. At the background level, the exotic field does not blow up whereas its kinetic energy and potential both grow without limit near the future singularity. We evaluate the classical stability of this background solution by examining the scalar perturbations of the metric along with the inclusion of entropy perturbation in the perturbed pressure. Within the Newtonian gauge, the gravitational field approaches a constant near the singularity plus additional regular terms. When the perturbed exotic field is associated with $\al>0$ the perturbed pressure and contrast density both diverge, whereas the perturbed exotic field and the divergence of the exotic field's velocity go to zero exponentially. When the perturbed exotic field is associated with $\al<0$ the contrast density always blows up, but the perturbed pressure can remain bounded. In addition, the perturbed exotic field and the divergence of the exotic field's velocity vanish near the big brake singularity. We also briefly look at the behavior of the intrinsic entropy perturbation near the singular event.