Some anisotropic universes in the presence of imperfect fluid coupling with spatial curvature

We consider Bianchi VI spacetime, which also can be reduced to Bianchi types VI0-V-III-I. We initially consider the most general form of the energy-momentum tensor which yields anisotropic stress and heat flow. We then derive an energy-momentum tensor that couples with the spatial curvature in a way so as to cancel out the terms that arise due to the spatial curvature in the evolution equations of the Einstein field equations. We obtain exact solutions for the universes indefinetly expanding with constant mean deceleration parameter. The solutions are beriefly discussed for each Bianchi type. The dynamics of the models and fluid are examined briefly, and the models that can approach to isotropy are determined. We conclude that even if the observed universe is almost isotropic, this does not necessarily imply the isotropy of the fluid (e.g., dark energy) affecting the evolution of the universe within the context of general relativity.Comment: 17 pages, no figures; to appear in International Journal of Theoretical Physics; in this version (which is more concise) an equation added, some references updated and adde

Bazı genel relativistik kozmolojik modeller

ÖZET Bu tezde, ısı akılı, vizkoz akışkanlı ve elektromagnetik alanlı inhomojen bir metriğin (Marder 1958) muhtelif çözümleri elde edilmiş çözümlerin fiziksel özellikleri ve asimptotik davranışları tartışılmıştır. Bulduğumuz modeller literatürdeki bu tip bazı modelleri genelleştiren ve onları özel hal olarak içeren modellerdir. SUMMARY In this thesis, several solutions of an inhomegeneous metric {Harder 1958) which have heat flux, viscous fluid and electromagnetic field are obtained and their some physical and geometrical features and asymtotic behaviours are argued. The obtained models generalize such kind models and containe them as special situations. 22ÖZET Bu tezde, ısı akılı, vizkoz akışkanlı ve elektromagnetik alanlı inhomojen bir metriğin (Marder 1958) muhtelif çözümleri elde edilmiş çözümlerin fiziksel özellikleri ve asimptotik davranışları tartışılmıştır. Bulduğumuz modeller literatürdeki bu tip bazı modelleri genelleştiren ve onları özel hal olarak içeren modellerdir. SUMMARY In this thesis, several solutions of an inhomegeneous metric {Harder 1958) which have heat flux, viscous fluid and electromagnetic field are obtained and their some physical and geometrical features and asymtotic behaviours are argued. The obtained models generalize such kind models and containe them as special situations. 2