Pseudo-rip: Cosmological models intermediate between the cosmological constant and the little rip

TL;DR

This paper explores the pseudo-rip cosmological model, an intermediate scenario where the universe's expansion rate approaches a constant, providing new models and analyzing their implications for cosmic structure disintegration.

Contribution

It introduces and analyzes pseudo-rip models, filling the gap between cosmological constant and little rip scenarios, with detailed behavior of the Hubble parameter.

Findings

Pseudo-rip models can have a non-monotonically increasing inertial force.

Models show the Hubble parameter approaches a constant at infinity.

Structure disintegration depends on specific model parameters.

Abstract

If we assume that the cosmic energy density will remain constant or strictly increase in the future, then the possible fates for the universe can be divided into four categories based on the time asymptotics of the Hubble parameter H(t): the cosmological constant, for which H(t) = constant, the big rip, for which H(t) goes to infinity at finite time, the little rip, for which H(t) goes to infinity as time goes to infinity, and the pseudo-rip, for which H(t) goes to a constant as time goes to infinity. Here we examine the last of these possibilities in more detail. We provide models that exemplify the pseudo-rip, which is an intermediate case between the cosmological constant and the little rip. Structure disintegration in the pseudo-rip depends on the model parameters. We show that pseudo-rip models for which the density and Hubble parameter increase monotonically can produce an inertial force which does not increase monotonically, but instead peaks at a particular future time and then decreases.