Generalized holographic and Ricci dark energy models

Abstract

In this paper, we consider generalized holographic and Ricci dark energy models where the energy densities are given as ρR=3c2Mpl2Rf(H2/R) and ρh=3c2Mpl2H2g(R/H2), respectively; here f(x), g(y) are positive defined functions of the dimensionless variables H2/R or R/H2. It is interesting that holographic and Ricci dark energy densities are recovered or recovered interchangeably when the function f(x)=g(y)≡1 or f(x)=Id and g(y)=Id are taken, respectively (for example f(x),g(x)=1−e(1−x), e=0or1, respectively). Also, when f(x)≡xg(1/x) is taken, the Ricci and holographic dark energy models are equivalent to a generalized one. When the simple forms f(x)=1−e(1−x) and g(y)=1−η(1−y) are taken as examples, by using current cosmic observational data, generalized dark energy models are considered. As expected, in these cases, the results show that they are equivalent (e=1−η=1.312), and Ricci-like dark energy is more favored relative to the holographic one where the Hubble horizon was taken as an IR cut-off. And the suggested combination of holographic and Ricci dark energy components would be 1.312R−0.312H2, which is \(2.312H^{2}+1.312\dot{H}\) in terms of H2 and \(\dot{H}\) .