Observational tests of Galileon gravity with growth rate

• Published in: General relativity and gravitation Vol. 48; no. 10; pp. 1 - 12
• Main Author: Hirano, Koichi
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.10.2016; Springer Nature B.V
• Subjects: Astronomy; Astrophysics and Cosmology; Baryons; Big Bang theory; Classical and Quantum Gravitation; Cosmic microwave background; Dark energy; Differential Geometry; Flux density; Gravitation; Gravity; Growth rate; Mathematical and Computational Physics; Physics; Physics and Astronomy; Quantum Physics; Relativity Theory; Research Article; Supernovae; Theoretical; Observational cosmology; Matter density perturbation; Growth rate; Modified gravity
• ISSN: 0001-7701; 1572-9532
• DOI: 10.1007/s10714-016-2129-z

We compare observational data of growth rate with the prediction by Galileon theory. For the same value of the energy density parameter Ω m , 0 , the growth rate in Galileon models is enhanced compared with the Λ CDM case, due to the enhancement of Newton’s constant. The smaller Ω m , 0 is, the more suppressed growth rate is. Hence the best fit value of Ω m , 0 in the Galileon model is 0.16 from only the growth rate data, which is considerably smaller than such value obtained from observations of supernovae Ia, the cosmic microwave background and baryon acoustic oscillations. We also find the upper limit of the Brans–Dicke parameter to be ω < - 1000 ( 1 σ ), from the growth rate data. In this paper, specific galileon models are considered, not the entire class. More and better growth rate data are required to distinguish between dark energy and modified gravity.