Multi-horizon spherically symmetric spacetimes with several scales of
  vacuum energy
  We present a family of spherically symmetric multi-horizon spacetimes with a
vacuum dark fluid, associated with a time-dependent and spatially inhomogeneous
cosmological term. The vacuum dark fluid is defined in a model-independent way
by the symmetry of its stress-energy tensor, i.e., its invariance under Lorentz
boosts in a distinguished spatial direction ($p_r=-\rho$ for spherical
symmetry), which makes the dark fluid essentially anisotropic and allows its
density to evolve. The related cosmological models belong to the Lemaitre class
of models with anisotropic fluids and describe a universe with several scales
of vacuum energy related to phase transitions during its evolution. The typical
behavior of solutions and the number of spacetime horizons are determined by
the number of vacuum scales. We study in detail a model with three vacuum
scales: GUT, QCD and that responsible for the present accelerated expansion.
The model parameters are fixed by the observational data and by analyticity and
causality conditions. We find that our Universe has three horizons. During the
first inflation the Universe enters a T-region which makes the expansion
irreversible. After the second phase transition at the QCD scale the Universe
enters an R-region, where for a long time its geometry remains almost
pseudo-Euclidean. After crossing the third horizon related to the present
vacuum density, the Universe should enter the next T-region with inevitable
expansion.
