Phantom Energy with Variable G and Lambda

Abstract

We have investigated a cosmological model of a phantom energy with a variable cosmological constant ($\Lambda$) depending on the energy density ($\rho$) as $\Lambda \propto {\rho }^{-\alpha }$, $\alpha =const.$ and a variable gravitational constant ($G$). The model requires $\alpha <0$ and a negative gravitational constant. A negative gravitational constant may forbid \emph{black holes} to form a particle horizon in a background of phantom energy. This implies that black holes are naked, and consequently the \emph{Cosmic Censorship} theorem is violated. The cosmological constant evolves with time as, $\Lambda \propto t^{-2}$. For $\omega >-1$ and $\alpha <-1$ the cosmological constant, $\Lambda <0$, $G>0$ and $\rho$ decrease with cosmic expansion. For ordinary matter (or dark matter), i.e., $\omega >-1$ we have $-1<\alpha <0$ and $\beta >0$ so that $G>0$ increases with time and $\rho$ decreases with time. Cosmic acceleration with dust particles is granted provided $-2/3<\alpha <0$ and $\Lambda >0$.

7 pages, revtex4

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Cited by in corpus (4)

• Reconstruction of cosmic history from a simple parametrization of H
• Interacting Holographic Viscous Dark Energy Model
• Statefinder Parameters for Different Dark Energy Models with Variable G Correction in Kaluza-Klein Cosmology
• Viscous FRW model with particle creation in the early universe