Cosmological horizons in regular bouncing backgrounds

TL;DR

This paper explores how cosmological horizons are influenced by the entire spacetime history, especially in bouncing models connecting different expansion phases with varying curvature.

Contribution

It provides examples showing that horizons depend on the full cosmological history, challenging common assumptions about horizons in accelerated or decelerated phases.

Findings

Horizons depend on the full spacetime history, not just local expansion properties.

Regular bouncing scenarios can connect phases with different horizon characteristics.

The study illustrates the complexity of horizon behavior in non-standard cosmological models.

Abstract

It is often stated that a phase of standard, decelerated cosmological expansion is characterised by the absence of global event horizons, while a phase of accelerated expansion is associated with the absence of particle horizons. This is not necessarily true because such horizons, being non-local properties of the spacetime geometry, depend on the full (past and future) history of the given cosmological background. We provide examples of various different scenarios for the case in which the final asymptotic phase of standard expansion and decreasing curvature is connected, through a regular bounce, with an initial (and possibly infinitely extended in time) regime of growing curvature.