Dark energy cosmological model with anisotropic fluid and time varying lambda in Kaluza-Klein metric

Abstract

In this paper, we have investigated the dark energy cosmological model in the presence of anisotropic fluid in Kaluza-Klein metric with generalized time-dependent lambda Λ=αH 2 + βS 2 (α, β are free parameters; H is Hubble parameter and S is normal scale factor). Considering the equation of state (EOS) p = ωρ for normal dimensions and pψ= (ω+δ)ρ for the fifth dimension, exact solutions of Einstein field equations of the anisotropic model are obtained (where p -the pressure for normal dimensions, pψ -the pressure of the fifth dimension, ρ -density of the fluid, ω -EOS parameter, and δ -skewness parameter). It is concluded that the universe at its early stage shows anisotropic behavior due to its finite value δ. The variations of ω and δ demonstrate the evolution from radiation dominated early universe to a dark energy-dominated universe. We have also investigated dark energy density, pressure, and other physical parameters. The physical parameters are dependent on free parameters and power index factor n which relates the extra dimension scale factor to the normal scale factor.