Cosmological volume acceleration in dust epoch: using scaling solutions and variable cosmological term $\Lambda (t)$ within an anisotropic cosmological model

Abstract

Under the premise that the current observations of the cosmic microwave background radiation set a very stringent limit to the anisotropy of the universe, we consider an anistropic model in the presence of a barotropic perfect fluid and a homogeneous scalar field, which transits to a flat FRW cosmology for late times in a dust epoch, presenting an accelerated volume expansion. Furtheremore, the scalar field is identified with a varying cosmological term via $V(\varphi (t))=2\Lambda (t)$. Exact solutions to the EKG system are obtained by proposing an anisotropic extension of the scaling solutions scenario: $\rho \sim {\eta }^{-\mathrm{n}},{\rho }_{\varphi }\sim {\eta }^{-\mathrm{m}}$, with ${\eta }^3={\mathrm{a}}_1{\mathrm{a}}_2{\mathrm{a}}_3$ the volume function of the anistropic model (${\mathrm{a}}_1,{\mathrm{a}}_2,{\mathrm{a}}_3$ being the scale factors).

12 pages, two figures, Mayor changes in abstract, introduction and title, and we add 11 references. To publish in Astrophysics Space Science Journal