Observational constraints on Galileon cosmology

TL;DR

This paper investigates the cosmological implications of covariant Galileon fields, comparing theoretical predictions with recent observational data to constrain model parameters and assess its viability relative to the standard LCDM model.

Contribution

It provides observational constraints on covariant Galileon cosmology, analyzing both tracker and generic solutions with and without cosmic curvature, and compares their fit to data against LCDM.

Findings

Tracker solutions are compatible with individual data but disfavored overall.

Generic solutions with non-zero curvature fit data well but are not favored over LCDM.

Including curvature broadens the viable parameter space for Galileon models.

Abstract

We study the cosmology of a covariant Galileon field with five covariant Lagrangians and confront this theory with the most recent cosmological probes: the type Ia supernovae data (Constitution and Union2 sets), cosmic microwave background (WMAP7) and the baryon acoustic oscillations (SDSS7). In the Galileon cosmology with a late-time de Sitter attractor, there is a tracker that attracts solutions with different initial conditions to a common trajectory. Including the cosmic curvature K, we place observational constraints on two distinct cases: (i) the tracker, and (ii) the generic solutions to the equations of motion. We find that the tracker solution can be consistent with the individual observational data, but it is disfavored by the combined data analysis. The generic solutions fare quite well when a non-zero curvature parameter is taken into account, but the Akaike and Bayesian information criteria show that they are not particularly favored over the LCDM model.