Effective Dark Energy Models and Dark Energy Models with Bounce in frames of $F(T)$ Gravity

TL;DR

This paper explores various $F(T)$ gravity cosmological models, demonstrating their ability to mimic $\Lambda$CDM evolution, produce phantom-like dark energy, avoid singularities, and include bouncing scenarios in the universe's future.

Contribution

It introduces new $F(T)$ gravity models that replicate $\Lambda$CDM behavior, allow phantom energy without singularities, and incorporate bouncing cosmologies.

Findings

Models can mimic $\Lambda$CDM evolution in the past.

Universe can avoid singularities with nonlinear energy density dependence.

Bouncing scenarios can replace future singularities.

Abstract

Various cosmological models in frames of $F(T)$ gravity are considered. The general scheme of constructing effective dark energy models with various evolution is presented. It is showed that these models in principle are compatible with $\Lambda$CDM model. The dynamics of universe governed by $F(T)$ gravity can mimics $\Lambda$CDM evolution in past but declines from it in a future. We also construct some dark energy models with the "real" (non-effective) equation-of-state parameter $w$ such that $w\leq-1$. It is showed that in $F(T)$ gravity the Universe filled phantom field not necessarily ends its existence in singularity. There are two possible mechanisms permitting the final singularity. Firstly due to the nonlinear dependence between energy density and $H^{2}$ ($H$ is the Hubble parameter) the universe can expands not so fast as in the general relativity and in fact Little Rip regime take place instead Big Rip. We also considered the models with possible bounce in future. In these models the universe expansion can mimics the dynamics with future singularity but due to bounce in future universe begin contracts.