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Cosmological observations suggest the existence of two different kinds of energy densities dominating at small (500Mpc) and large (1000Mpc) scales. The dark matter component, which dominates at small scales, contributes ₌0. 35 and has an equation of state p=0, while the dark energy component, which dominates at large scales, contributes ₕ0. 65 and has an equation of state p-. It is usual to postulate weakly interacting massive particles (WIMPs) for the first component and some form of scalar field or cosmological constant for the second component. We explore the possibility of a scalar field with a Lagrangian L=-V () 1-{^i₈} acting as both clustered dark matter and smoother dark energy and having a scale-dependent equation of state. This model predicts a relation between the ratio r=ₕ/₃₌ of the energy densities of the two dark components and an expansion rate n of the universe with a (t) t^n in the form n= (2/3) (1+r). For r2, we get n2 which is consistent with observations.
Padmanabhan et al. (Tue,) studied this question.