Experimental constraints on the uncoupled Galileon model from SNLS3 data and other cosmological probes

TL;DR

This paper tests the Galileon modified gravity model against cosmological data, deriving a new parameter definition to avoid initial condition choices, and finds it remains consistent with observations and competitive with DM.

Contribution

It introduces a new way to define Galileon parameters that bypass initial condition selection and tests the model against multiple cosmological probes.

Findings

Galileon model remains consistent with current data

Small tension between growth and distance constraints

Model is competitive with DM

Abstract

The Galileon model is a modified gravity theory that may provide an explanation for the accelerated expansion of the Universe. This model does not suffer from instabilities or ghost problems (normally associated with higher-order derivative theories), restores local General Relativity -- thanks to the Vainshtein screening effect -- and predicts late time acceleration of the expansion. In this paper, we derive a new definition of the Galileon parameters that allows us to avoid having to choose initial conditions for the Galileon field, and then test this model against precise measurements of the cosmological distances and the rate of growth of cosmic structures. We observe a small tension between the constraints set by growth data and those from distances. However, we find that the Galileon model remains consistent with current observations and is still competitive with the \Lambda CDM model, contrary to what was concluded in recent publications.