The holographic dark energy in non-flat Brans–Dicke cosmology

Interacting holographic dark energy model in non-flat universe

When taking the holographic principle into account, the vacuum energy will acquire dynamical property that its equation of state is evolving. The current available observational data imply that the holographic vacuum energy behaves as quintom-type dark energy. We adopt the viewpoint of that the scalar-field models of dark energy are effective theories of an underlying theory of dark energy. If we regard the scalar-field model as an effective description of such a holographic vacuum theory, we should be capable of using the scalar-field model to mimic the evolving behavior of the dynamical vacuum energy and reconstructing this scalar-field model according to the fits of the observational dataset. We find the generalized ghost condensate model is a good choice for depicting the holographic vacuum energy since it can easily realize the quintom behavior. We thus reconstruct the function h(phi) of the generalized ghost condensate model using the best-fit results of the observational data.

Dynamical vacuum energy, holographic quintom, and the reconstruction of scalar-field dark energy

In this paper we consider the holographic model of interacting dark energy in non-flat universe. With the choice of c≤0.84, the interacting holographic dark energy can be described by a phantom scalar field. Then we show this phantomic description of the holographic dark energy with c≤0.84 and reconstruct the potential of the phantom scalar field.

Interacting holographic phantom

Holographic dark energy

Motivated by recent results on non-vanishing spatial curvature \cite{curve} we employ the holographic model of dark energy to investigate the validity of first and second laws of thermodynamics in non-flat (closed) universe enclosed by apparent horizon $R_A$ and the event horizon measured from the sphere of horizon named $L$. We show that for the apparent horizon the first law is roughly respected for different epochs while the second laws of thermodynamics is respected while for $L$ as the system's IR cut-off first law is broken down and second law is respected for special range of deceleration parameter. It is also shown that at late-time universe $L$ is equal to $R_A$ and the thermodynamic laws are hold, when the universe has non-vanishing curvature. Defining the fluid temperature to be proportional to horizon temperature the range for coefficient of proportionality is obtained provided that the generalized second law of thermodynamics is hold.

S. Shafei

Papers

The Holographic Model of Dark Energy and Thermodynamics of Non-Flat Accelerated Expanding Universe