Linear perturbations on a cosmological background in relativistic theory of gravitation. I.Theory

The system of ordinary differential equations of the second order describing evolution of small perturbations of gravitational field and matter characteristics in RTG have been obtained, with cosmological solution being a background. It was shown also that these equations admit effective gauge invariance, because one can neglect the mass of the graviton in most cases of interest. The standard expansion on scalar, vector and tensor components has been performed. The equations of each component have been derived.