Light propagation with nonminimal couplings in a two-component cosmic dark fluid with an Archimedean-type force, and unlighted cosmological epochs

摘要: During the evolution of universe there are at least two epochs during which electromagnetic waves cannot scan universe's internal structure to bring information outside observers. The first epoch is when photons in local thermodynamic equilibrium with other particles, and second photon scattering by charged particles strong. One can call these periods cosmological time as standard unlighted epochs. After last surface, become relic turn into a source about universe. Unlighted cosmic also appear one considers nonminimal theories, i.e., theories field coupled an intricate way gravitational field. By considering model where dark sector, energy matter, self-interacts via Archimedean-type force, taking account coupling theory for field, we discuss appearance In framework our theory, three-parameter Einstein-Maxwell model, curvature be formulated terms effective refraction index $n(t)$. Then, advantage well-known classical analogy, namely, medium ${n}^{2}l0$ do not propagate their group velocity, transfer has zero value boundary corresponding zone, search arising interacting fluid model. We study here, both analytically numerically, models admitting