Interacting Ghost Dark Energy in Complex Quintessence Theory

TL;DR

This paper explores complex quintessence cosmology with ghost dark energy, analyzing its dynamics, stability, and parameter relationships, and finds that interaction is necessary for realistic energy density values.

Contribution

It introduces a complex quintessence model with ghost dark energy, analyzing its stability and parameter relations, which was not addressed in prior real models.

Findings

Non-interacting model leads to unphysical energy densities.

Interacting model can match observed dark energy density with specific coupling.

A relationship between  and b^2 parameters is established in the complex model.

Abstract

We employ a ghost model of interacting dark energy to obtain the equation of state \omega for ghost energy density in an FRW universe in complex quintessence theory. We reconstruct the potential and study the dynamics of the scalar field that describes complex quintessence cosmology. We perform \omega-\omega' analysis and stability analysis for both non-interacting and interacting cases and find that the same basic conclusion as for the real model, where \omega' = d\omega/dlna. Taking account of the effect of the complex part and assuming the real part of the quintessence field to be a "slow-rolling" field, we conclude that the non-interacting model cannot describe the real universe since this will lead to fractional energy density \Omega_D > 1, where \Omega_D can be defined as the ratio of \rho_D to \rho_{cr}. However, for the interacting case, if we take present \Omega_D = 0.73, then we can determine that b^2 = 0.0849, where b^2 is the interaction coupling parameter between matter and dark energy. In the real quintessence model, \Omega_D and b^2 are independent parameters, whereas in the complex quintessence model, we conclude that there is a relationship between these two parameters.