6533b830fe1ef96bd1297968

RESEARCH PRODUCT

Testing vector-tensor gravity with current cosmological observations

subject

description

A certain vector-tensor theory of gravitation (VT) has been recently applied to cosmology (Phys. Rev. D, 89, 2014, 044035). It leads to encouraging results. The zero order energy density of the vector field accounts for the cosmological constant. It has been recently proved that the VT vector field cannot play the role of the electromagnetic field. The evolution of the scalar perturbations is different in VT and general relativity. Tensor fluctuations evolve in the same way in both theories. Here, the VT evolution equations of the scalar modes are appropriately written, and the initial conditions at high redshift - for numerical integration- are given. The codes COSMOMC and CAMB are modified for applications to VT cosmology and, then, by using the new version of COSMOMC, statistical methods (Markov chains) allow us to fit theoretical VT predictions with current cosmological data obtained in various experiments. Previous encouraging fits were based on WMAP7 data, SN Ia observations, and a minimal model involving seven cosmological parameters. Here a similar preliminary study based on PLANCK data and updated SN Ia observations is presented.