Realizing interactions between dark matter and dark energy using k-essence cosmology

Abstract

In this paper, we exploit dynamics of a [Formula: see text]-essence scalar field to realize interactions between dark components of universe resulting in an evolution consistent with observed features of late-time phase of cosmic evolution. Stress–energy tensor corresponding to a [Formula: see text]-essence Lagrangian [Formula: see text] (where [Formula: see text]) is shown to be equivalent to an ideal fluid with two components having same equation of state. Stress–energy tensor of one of the components may be generated from a constant potential [Formula: see text]-essence Lagrangian of form [Formula: see text] ([Formula: see text] constant) and that of other from another Lagrangian of form [Formula: see text] with [Formula: see text]. We have shown that the unified dynamics of dark matter and dark energy described by a single scalar field [Formula: see text] driven by a [Formula: see text]-essence Lagrangian [Formula: see text] may be viewed in terms of diffusive interactions between the two hypothetical fluid components “1” and “2” with stress–energy tensors equivalent to that of Lagrangians [Formula: see text] and [Formula: see text], respectively. The energy transfer between the fluid components is determined by functions [Formula: see text], [Formula: see text] and their derivatives. Such a realization is shown to be consistent with the Supernova Ia data with certain constraints on the temporal behavior of [Formula: see text]-essence potential [Formula: see text]. We have described a methodology to obtain such constraints.