Constraining Galileon Gravity from Observational Data with Growth Rate(Astrophysics and Cosmology)

概要

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We studied the cosmological constraints on Galileon gravity obtained from observational data of the growth rate of matter density perturbations, the supernovae Ia (SN Ia), the cosmic microwave background (CMB), and baryon acoustic oscillations (BAO). For the same value of the energy density parameter of matter Ω_<m,0>, the growth rate f in Galileon models is enhanced relative to the ΛCDM case, because of an increase in Newton's constant. The smaller the Ω_<m,0>, the more the growth rate is suppressed. Therefore, the best fit value of Ω_<m,0> in the Galileon model, based only on the growth rate data, is quite small. This is incompatible with the value of Ω_<m,0> obtained from the combination of SN Ia, CMB, and BAO data. On the other hand, in the ΛCDM model, the values of Ω_<m,0> obtained from different observational data sets are consistent. In the analysis presented in this paper, we found that the Galileon model is less compatible with observations than the ΛCDM model. This result seems to be qualitatively the same in most of the generalized Galileon models in which Newton's constant is enhanced.
2012-06-25