Unified description of dark energy and dark matter candidates with the dark energy interiors

We overview the systematic approach to the unified description of dark energy (DE) and a certain class of dark matter (DM) candidates represented by stress–energy tensors with the algebraic structure $T_t^t=T_r^r$, qualified as a vacuum dark fluid. Most of the relevant solutions to the Einstein equations presented in the literature satisfy this condition. Regular solutions describe spacetimes with the non-zero background cosmological constant and de Sitter center surrounded by intrinsically anisotropic $r$-dependent quintessence. Dependently on the choice of the reference frame, they describe the Lemaître class cosmological models with the initial and final de Sitter stages, and regular compact objects with the de Sitter centers. For a special class of Lemaître cosmological models the universe evolution is guided by the quantum evaporation of the cosmological horizon, which uniquely determines the non-zero final value of the vacuum energy density ${\rho }_{vac}$. Regular compact objects with the de Sitter centers include regular black holes, their remnants, whose existence is supported by spacetime symmetry, and self-gravitating solitons G-lumps replacing naked singularities. For a special class of regular rotating compact objects distinguished by the energy conditions, interiors contain regions of anisotropic $r$-dependent phantom fluid. Regular primordial black holes, their remnants and G-lumps can be qualified as heavy DM candidates with DE interiors. Their observational signatures provide information about the matter content of their interiors.