More on the holographic Ricci dark energy model: smoothing Rips through interaction effects?

TL;DR

This paper investigates the late Universe's cosmological dynamics within a holographic Ricci dark energy model, exploring various dark sector interactions that can eliminate future singularities and lead to novel asymptotic states like Little Bangs.

Contribution

It introduces new interaction scenarios in the holographic Ricci dark energy model that replace the Big Rip with stable de Sitter or Minkowski states and discovers two novel future bouncing solutions.

Findings

Most interactions remove the Big Rip singularity.

Identifies two new future asymptotic states: Little Bang and Little Sibling of the Big Bang.

Demonstrates interaction effects can lead to non-singular cosmic evolutions.

Abstract

The background cosmological dynamics of the late Universe is analysed on the framework of a dark energy model described by an holographic Ricci dark energy component. Several kind of interactions between the dark energy and the dark matter components are considered herein. We solve the background cosmological dynamics for the different choices of interactions with the aim to analyse not only the current evolution of the universe but also its asymptotic behaviour and, in particular, possible future singularities removal. We show that in most of the cases, the Big Rip singularity, a finger print of this model in absence of an interaction between the dark sectors, is substituted by a de Sitter or a Minkowski state. Most importantly, we found two new {\textit{ future}} bouncing solutions leading to two possible asymptotic behaviours, we named Little Bang and Little Sibling of the Big Bang. At a Little Bang, as the size of the universe shrinks to zero in an infinite cosmic time, the Hubble rate and its cosmic time derivative blow up. In addition, at a Little sibling of the Big Bang, as the size of the universe shrinks to zero in an infinite cosmic time, the Hubble rate blows up but its cosmic time derivative is finite. These two abrupt events can happen as well in the past.