Comments on Unified dark energy and dark matter from a scalar field different from quintessence

Abstract

In a recent paper by C. Gao, M. Kunz, A. Liddle and D. Parkinson [1] the unification of dark matter and dark energy was explored within a theory, which they say is not of the Lagrangian type, containing a scalar field. This scalar field, different from the classic quintessence, can be obtained from the scalar field representation of an interacting twofluid mixture described in the paper by L.P. Chimento and M. Forte [2]. The corresponding Lagrangian of the model is just the equation (7).