New holographic dark energy and the modified Bekenstein-Hawking entropy

Abstract

We show that in the standard derivation of the holographic dark energy some conceptual issues are present. In particular, the formula used in the literature to avoid black holes is not suitable in expanding universes. A more suitable expression for a holographic motivated dark energy must contain the energy density of the remaining matter content of the universe. However, we show that under some reasonable hypothesis, we can obtain a new physically motivated expression for the holographic dark energy. By considering an appropriate time-dependence of the saturation-level parameter, a de Sitter phase arises. Moreover, by adopting an argument similar to the original Bekenstein one, our approach justifies a correction of the Bekenstein-Hawking entropy for non-static isotropic expanding universes. Finally, we write down the equation of state of a black hole embedded in Friedmann spacetimes.