Consistency of Cubic Galileon Cosmology: Model-Independent Bounds from Background Expansion and Perturbative Analyses

TL;DR

This paper evaluates the cubic Galileon cosmology model's consistency with background expansion data, perturbative analyses, and theoretical conjectures, highlighting its compatibility at the background level but limitations in growth index bounds.

Contribution

It provides a comprehensive analysis of the cubic Galileon model's viability using model-independent background and perturbative data, including theoretical constraints.

Findings

Compatible with background expansion data and preferred over quintessence.

Fails to satisfy growth index bounds from linear perturbations.

Consistent with the trans-Planckian censorship and Swampland conjectures.

Abstract

We revisit the cosmological dynamics of the cubic Galileon model in light of the recently proposed model-independent analyses of the Pantheon supernova data. At the background level, it is shown to be compatible with data and preferred over standard quintessence models. Furthermore, the model is shown to be consistent with the trans-Planckian censorship conjecture (as well as other Swampland conjectures). It is shown that for the given parametrization, the model fails to satisfy the bounds on the reconstructed growth index derived from the Pantheon data set at the level of linear~perturbations.