Rastall cosmology

TL;DR

This paper discusses how Rastall's theory of gravity can address issues in cosmological models like the generalized Chaplygin gas by using non-canonical scalar fields, revealing new features in such models.

Contribution

It introduces Rastall's theory as a framework to improve cosmological models with scalar fields, highlighting its potential to resolve existing tensions in observational data.

Findings

Rastall's theory can incorporate non-canonical scalar fields effectively.

The theory offers new features in cosmological modeling.

It potentially resolves background and perturbative tensions in Chaplygin gas models.

Abstract

We review the difficulties of the generalized Chaplygin gas model to fit observational data, due to the tension between background and perturbative tests. We argue that such issues may be circumvented by means of a self-interacting scalar field representation of the model. However, this proposal seems to be successful only if the self-interacting scalar field has a non-canonical form. The latter can be implemented in Rastall's theory of gravity, which is based on a modification of the usual matter conservation law. We show that, besides its application to the generalized Chaplygin gas model, other cosmological models based on Rastall's theory have many interesting and unexpected new features.