First experimental constraints on the disformally coupled Galileon model
Abstract
Aims. The Galileon model is a modified gravity model that can explain
the late-time accelerated expansion of the Universe. In a previous work, we derived
experimental constraints on the Galileon model with no explicit coupling to matter and
showed that this model agrees with the most recent cosmological data. In the context of
braneworld constructions or massive gravity, the Galileon model exhibits a disformal
coupling to matter, which we study in this paper.Methods. After comparing our constraints on the uncoupled model with
recent studies, we extend the analysis framework to the disformally coupled Galileon model
and derive the first experimental constraints on that coupling, using precise measurements
of cosmological distances and the growth rate of cosmic structures.Results. In the uncoupled case, with updated data, we still observe a
low tension between the constraints set by growth data and those from distances. In the
disformally coupled Galileon model, we obtain better agreement with data and favour a
non-zero disformal coupling to matter at the 2.5σ level. This gives an interesting hint of the
possible braneworld origin of Galileon theory.
Domains
Astrophysics [astro-ph]
Origin : Publication funded by an institution
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