Cosmologias não singulares com vácuo interagente

Abstract

In this work we try to study a possible solution to the cosmological singularity problem by analyzing the dynamics of FLRW cosmology where a vacuum component interacts with a perfect fluid through an energy exchange. We analyzed two different covariant choices for energy transfer. In the first case the dynamics are integrable and the obtained Friedmann’s equation has an effective potential with a barrier that prevents the formation of the singularity through a bounce. In the second case, the transfer energy is a non-linear combination of the vacuum and the energy density of the fluid. In this case, the dynamic equations can be partially integrated, leading to a first integral, and reducing the number of degrees of freedom of the system. For a domain of parameter values it is possible to find non-singular solutions. In both cases the phase space structure allows non-singular orbits that recover the dynamics of the ΛCDM model in a low energy regime – after the last scattering surface.