Phantom Instability of Viscous Dark Energy in Anisotropic Space-Time

TL;DR

This paper explores how bulk viscosity in an anisotropic universe can temporarily induce phantom dark energy behavior, which decays over time, reconciling observations with quantum stability.

Contribution

It introduces a mechanism where bulk viscosity causes transient phantom behavior in dark energy within an anisotropic space-time, and reconstructs scalar field potentials.

Findings

Bulk viscosity can temporarily drive dark energy into the phantom regime.

Phantom behavior decays over time, approaching a cosmological constant.

Scalar field potentials are reconstructed for viscous and non-viscous models.

Abstract

Phantom dark energy is a proposal that explains the current observations that mildly favor the equation of state of dark energy $\omega^{de}$ crossing -1 at 68% confidence level. However, phantom fields are generally ruled out by ultraviolet quantum instabilities. To overcome this discrepancy, in this paper we propose a mechanism to show that how the presence of bulk viscosity in the cosmic fluid can temporarily drive the fluid into the phantom region ($\omega<-1$). As time is going on, phantom decays and ultimately $\omega^{de}$ approaches to -1. Then we show these quintessence and phantom descriptions of non-viscous and viscous dark energy and reconstruct the potential of these two scalar fields. Also a diagnostic for these models are performed by using the statefinder pairs $\{s,r\}$. All results are obtained in an anisotropic space-time which is a generalization of FLRW universe.