An oscillating Rastall universe crossing the phantom divide line

TL;DR

This paper proposes a cyclic universe model within Rastall gravity that oscillates between expansion and contraction, crossing the phantom divide line, and explores its thermodynamics, energy conditions, and singularities.

Contribution

It introduces a novel oscillating Rastall universe model with cyclic behavior and phantom crossing, extending standard cosmology frameworks.

Findings

Universe exhibits periodic oscillations in the Hubble parameter.

Cosmic transit occurs around 8.7 Gyr, with thermodynamical analysis supporting the model.

Energy conditions are satisfied except near singularities.

Abstract

A cyclic flat universe with quintom behaviour and future big rip has been presented in the framework of Rastall gravity, which is an extension of the standard $\Lambda$CDM model. The Hubble parameter oscillates periodically between positive and negative values from one cycle to the next. Cosmic transit has been simulated through an oscillating time-dependent deceleration parameter, and is expected to occur at approximately $ 8.7~~ \text{Gyr}$. The causality is satisfied all the time except near the initial singularity and the future Big Rip singularity.The apparent horizon, entropy and other thermodynamical quantities associated to the current model have been analyzed. Energy conditions have been investigated.