Radiation in the process of the voids formation

We develop a model of void formation, which simulates the evolution of voids from the moment of the last scattering until the present instant. We find that in order to obtain a model which would be fully consistent with the observational constraints the existence of radiation must be taken into account. The ratio of radiation energy density to matter energy density in CDM models at the moment of last scattering is 1/5. Such a high value of radiation energy density cannot be omitted. Namely, it is important to the process of the structure formation and hence significantly influences the dynamics of the Universe in first millions of years after the last scattering. From the fact that the evolution of voids proceeds differently in various cosmological background models we use the process of void formation to put some limits on values of cosmological parameters. We find that the model with Ωmat ∼ 0.3 fits the observational data best. Unfortunately, conclusions about the exact value of the cosmological constant cannot be drawn because of insufficiently precise observational data.