Holographic Ricci Dark Energy Model with Non-constant c 2 Term
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Holographic Ricci Dark Energy Model with Non-constant c2 Term Hassan Saadat
Received: 3 September 2012 / Accepted: 5 November 2012 / Published online: 14 November 2012 © Springer Science+Business Media New York 2012
Abstract In this paper, we study holographic Ricci dark energy model with non-constant c2 term in dark energy density formula. We consider FRW metric in flat space-time and calculate density. Also we find scale factor and Hubble expansion parameter. Keywords Dark energy · Holographic Ricci scalar energy
1 Introduction As we know the dark energy is a mysterious fuel which is cause of accelerated expansion of the Universe. There are many observations verified this statement such as the observation of type Ia supernovae [1–4], detection of the cosmic microwave background anisotropy [5–7], observations from SDSS [8–10]. Dark energy is a special form of energy which tends to increase the rate of expansion of the universe. There are usually two ways for modeling the dark energy, a particular parametrization and modifications of gravity at very large scale. In order to find the dark energy equation of state from observational data there are three important ways which are solving the scalar field equations, building a functional form for equation of state parameter, and performing a parameter-free approach. Comparing the recent observational data with various models of dark energy tells the vacuum energy density and a dynamical scalar field are two important candidates for dark energy. So, the equation of state associated with the vacuum energy density is constant. Also it may be a function of time in generic quintessence scenarios [11–14]. Another important candidate for the dark energy is a positive cosmological constant [15–17]. One of the important ways to specify the nature of the dark energy is to study the time-dependent dark energy density. In that case the relation between dark matter density and temperature of the dark universe have already been studied [18]. Also the effect of dark matter on the solar system have already considered [19, 20] which are extended to the case of the dark energy [21–28]. H. Saadat () Department of Physics, Sepidan Branch, Islamic Azad University, P.O. Box 71555-477, Sepidan, Iran e-mail: [email protected]
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Int J Theor Phys (2013) 52:1027–1032
In Ref. [21], the relation between the time-dependent dark energy density and temperature of the dark universe is investigated. Recently, the weak gravity conjecture has been applied to explain the dark energy which is called the holographic dark energy model [22– 27]. In Ref. [28], the holographic dark energy model with interaction and space curvature considered. In Ref. [29], the cosmological model based on the holographic dark energy considered. We studied the dark energy density in the Universe with arbitrary spatially curvature which is described by the Friedmann-Robertson-Walker (FRW) metric. We used ChevallierPolarski- Linder (CPL) parametrization to specify dark energy density and used another parametrization cal
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