FRW models with particle creation in Brans-Dicke theory

The thermodynamical effect of particle creation on the early evolution of Friedmann-Robertson-Walker universe is analyzed in the context of open thermodynamical systems within the framework of Brans-Dicke theory. The field equations are solved exactly using the “gamma-law” equation of state p=(γ−1)ρ, where the adiabatic parameter γ depends on the scale factor of the universe. We assume the functional form of γ in such a way that it describes a unified description of two early phases of the evolution of the universe, viz. inflationary phase and radiation-dominated phase. The role of Brans-Dicke scalar and creation of matter particles is investigated during the expansion of the universe. It is found that the expansion of the universe is driven by the particle creation in each phase. The physical and geometrical behaviors of the solutions are discussed in detail.