Cosmic dynamics and qualitative study of Rastall model with spatial curvature

TL;DR

This paper explores the cosmic dynamics of Rastall gravity in non-flat FRW space-time, analyzing critical points, stability, and cosmological solutions including de Sitter expansion and bouncing universes, highlighting differences from standard cosmology.

Contribution

It provides a detailed autonomous system analysis of Rastall gravity with spatial curvature, revealing stable cosmological solutions and bouncing scenarios not present in standard models.

Findings

De Sitter universe at late times in expanding cosmology

Oscillating solutions in positive spatial curvature for bouncing cosmology

Non-singular universe models using energy conditions

Abstract

We investigate the cosmic dynamics of Rastall gravity in non-flat Friedmann-Robertson-Walker (FRW) space-time with barotropic fluid. In this context, we are concerned about the class of model satisfying the affine equation of state. We derive the autonomous system for the Rastall model with barotropic fluid. We apply the derived system to investigate the critical points for expanding and bouncing cosmologies and their stable nature and cosmological properties. The expanding cosmology yields de Sitter universe at late times with decelerating past having matter and radiation dominated phases. Investigation of autonomous system for bouncing cosmology yields oscillating solutions in positive spatial curvature region. We also investigate the consequences of setting-up a model of non-singular universe by using energy conditions. The distinct features of the Rastall model compared to the standard model have been discussed in detail.