Exact solution and exotic fluid in cosmology (Q406166)

Summary: We investigate cosmological consequences of nonlinear sigma model coupled with a cosmological fluid which satisfies the continuity equation. The target space action is of the de Sitter type and is composed of four scalar fields. The potential which is a function of only one of the scalar fields is also introduced. We perform a general analysis of the ensuing cosmological equations and give various critical points and their properties. Then, we show that the model exhibits an exact cosmological solution which yields a transition from matter domination into dark energy epoch and compare it with the \(\Lambda\)-CDM behavior. Especially, we calculate the age of the Universe and show that it is consistent with the observational value if the equation of the state \(\omega_f\) of the cosmological fluid is within the range of \(0.13<\omega_f<0.22\). Some implication of this result is also discussed.