Graphical and Kinematical Approach to Cosmological Horizons

TL;DR

This paper provides a graphical and analytical kinematical framework to understand the formation and properties of cosmological event horizons in accelerating universes, revealing their asymptotic behavior and conditions for horizon absence.

Contribution

It introduces a novel kinematical approach to analyze cosmological horizons, independent of dynamical equations, and identifies conditions for horizon existence or absence in accelerating models.

Findings

All horizons tend to a specific asymptotic form at future infinity.

Certain accelerating models lack horizons due to their geometric properties.

The approach applies to de Sitter and quintessence cosmologies, recovering known results.

Abstract

We study the apparition of event horizons in accelerated expanding cosmologies. We give a graphical and analytical representation of the horizons using proper distances to coordinate the events. Our analysis is mainly kinematical. We show that, independently of the dynamical equations, all the event horizons tend in the future infinity to a given expression depending on the scale factor that we call asymptotic horizon. We also encounter a subclass of accelerating models without horizon. When the ingoing null geodesics do not change concavity in its cosmic evolution we recover the de Sitter and quintessence-Friedmann-Robertson-Walker models.