Cosmological Evolution Across Phantom Crossing and the Nature of the Horizon

TL;DR

This paper investigates the universe's evolution across the phantom barrier, analyzing horizon behavior and potential singularities during accelerated expansion driven by quintessence or phantom matter.

Contribution

It studies the transition across the phantom barrier and examines horizon changes and singularity possibilities in the context of cosmological evolution.

Findings

Horizon behavior changes across the phantom barrier.

Potential singularities may occur in the phantom era.

The universe's accelerated expansion relates to matter violating energy conditions.

Abstract

In standard cosmology, with the evolution of the universe, the matter density and thermodynamic pressure gradually decreases. Also in course of evolution, the matter in the universe obeys (or violates) some restrictions or energy conditions. If the matter distribution obeys strong energy condition (SEC), the universe is in a decelerating phase while violation of SEC indicates an accelerated expansion of the universe. In the period of accelerated expansion the matter may be either of quintessence nature or of phantom nature depending on the fulfilment of the weak energy condition (WEC) or violation of it. As recent observational evidences demand that the universe is going through an accelerated expansion so mater should be either quintessence or phantom in nature. In the present work we study the evolution of the universe through the phantom barrier (i.e. the dividing line between the quintessence and phantom era) and examine how apparent and event horizon change across the barrier. Finally, we investigate the possibility of occurrence of any singularity in phantom era.