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

¹ CEA,Centre de Saclay, Irfu/SPP, 91191 Gif-sur-Yvette, France
e-mail: jeremy.neveu@cea.fr
² Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309-0389, USA
³ LPNHE, Université Pierre et Marie Curie, Université Paris Diderot, CNRS-IN2P3, 4 place Jussieu, 75252 Paris Cedex 05, France
⁴ Laboratoire de Physique Théorique d’Orsay, Bâtiment 210, Université Paris-Sud 11, 91405 Orsay Cedex, France
⁵ 𝒢ℝεℂ𝒪, Institut d’Astrophysique de Paris, UMR 7095-CNRS, Université Pierre et Marie Curie-Paris 6, 98bis boulevard Arago, 75014 Paris, France

Received: 7 February 2013
Accepted: 25 April 2013

Abstract

Aims. 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.

Methods. We derive a new definition of the Galileon parameters that allows us to avoid having to choose initial conditions for the Galileon field. We tested this model against precise measurements of the cosmological distances and the rate of growth of cosmic structures.

Results. We observe a weak 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 ΛCDM model, contrary to what was concluded in recent publications.