K-essential covariant holography

Abstract

The holographic principle is applied to a flat Friedmann-Robertson-Walker space-time dominated by dark energy when this is due to the presence of a k-essence scalar field, both for dark energy and phantom scenarios. In this framework, a geometrical covariant approach permits the construction of holographic hypersurfaces. The resulting covariant preferred screens, both for phantom and non-phantom regions, are then compared with those obtained by using the holographic dark energy model with the future event horizon as the infrared cut-off. In the phantom case, one of the two obtained holographic screens is placed on the big rip hypersurface, both for the covariant holographic formalism and the holographic phantom model. It is also analysed whether this covariant formalism allows a mathematically consistent formulation of fundamental theories based on the existence of a S-matrix at infinite distances.Comment: 14 pages, 6 figures. Accepted for publication in General Relativity and Gravitation. arXiv admin note: substantial text overlap with arXiv:1407.842

Cosmological constraints on a unified dark matter-energy scalar field model with fast transition

“…The first UDM model with fast transition was introduced in [30] and prescribed the evolution of p. The pressure and energy density were related by a barotropic EOS, p = p(ρ) and the perturbations were adiabatic. A second UDM model with fast transition was presented in [31] and was built from a k-essence [32,33] scalar field Lagrangian (see also [34][35][36][37]). This model also prescribed p but, differently from the first one, since it is based on a scalar field the perturbations are naturally nonadiabatic [38,39], allowing for a small Jeans length even when the speed of sound is non-negligible.…”