Abstract
We present the regular cosmological models of the Lemaître class with time-dependent and spatially inhomogeneous vacuum dark energy, which describe relaxation of the cosmological constant from its value powering inflation to the final non-zero value responsible for the present acceleration in the frame of one self-consistent theoretical scheme based on the algebraic classification of stress-energy tensors and spacetime symmetry directly related to their structure. Cosmological evolution starts with the nonsingular non-simultaneous de Sitter bang, followed by the Kasner-type anisotropic expansion, and goes towards the present de Sitter state. Spacetime symmetry provides a mechanism of reducing cosmological constant to a certain non-zero value involving the holographic principle which singles out the special class of the Lemaître dark energy models with the global structure of the de Sitter spacetime. For this class cosmological evolution is guided by quantum evaporation of the cosmological horizon whose dynamics entirely determines the final value of the cosmological constant. For the choice of the density profile modeling vacuum polarization in a spherical gravitational field and the GUT scale for the inflationary value of cosmological constant, its final value agrees with that given by observations. Anisotropy grows quickly at the postinflationary stage, then remains constant and decreases to A < 10 − 6 when the vacuum density starts to dominate.
Highlights
Observational data convincingly testify that our Universe is dominated at above 72% of its density by a dark energy with a negative pressure p = wρ, w < −1/3 [1,2,3,4], with the best fit w = −1 corresponding to the cosmological constant λ associated with the vacuum density ρvac = (8πG )−1 λ [6,7,8,9,10,11]
A vacuum dark energy is introduced in general setting suggested by the algebraic classification of stress-energy tensors and directly related to spacetime symmetry that provides a mechanism of reducing a cosmological constant to a certain non-zero value involving the holographic principle which singles out the special class of the Lemaître cosmological models with the global structure of the de Sitter spacetime
Such geometries describe the relaxation of the cosmological constant by the Lemaître class anisotropic cosmological models, which reduce to the isotropic FLRW models at the stages with the spacetime symmetry restored to the de Sitter group
Summary
A vacuum dark energy is introduced in general setting suggested by the algebraic classification of stress-energy tensors and directly related to spacetime symmetry that provides a mechanism of reducing a cosmological constant to a certain non-zero value involving the holographic principle which singles out the special class of the Lemaître cosmological models with the global structure of the de Sitter spacetime. In a similar way a dynamical vacuum dark energy associated with a variable cosmological term, generates geometries whose basic properties involve in the natural way restoration of the spacetime symmetry asymptotically or/and at certain stages of the universe evolution Such geometries describe the relaxation of the cosmological constant by the Lemaître class anisotropic cosmological models, which reduce to the isotropic FLRW models at the stages with the spacetime symmetry restored to the de Sitter group.
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