Coupling dark energy to dark matter inhomogeneities

Abstract

We propose that dark energy in the form of a scalar field could effectively couple to dark matter inhomogeneities. Through this coupling energy could be transferred to/from the scalar field, which could possibly enter an accelerated regime. Though phenomenological, this scenario is interesting as it provides a natural trigger for the onset of the acceleration of the universe, since dark energy starts driving the expansion of the universe when matter inhomogeneities become sufficiently strong. Here we study a possible realization of this idea by coupling dark energy to dark matter via the linear growth function of matter perturbations. The numerical results show that it is indeed possible to obtain a viable cosmology with the expected series of radiation, matter and dark-energy dominated eras. In particular, the current density of dark energy is given by the value of the coupling parameters rather than by very special initial conditions for the scalar field. In other words, this model - unlike standard models of cosmic late acceleration - does not suffer from the so-called "coincidence problem" and its related fine tuning of initial conditions.Comment: 12 pages, 2 figures; revised and expanded discussion of proposed interaction and figures; matches version accepted for publication in Physics of the Dark Univers

Cosmological constraints on parametrized interacting dark energy

“…Since we consider a constant EoS parameter, the adiabatic sound speed square c 2 a coincides with w. In order to avoid instabilities, the physical sound speed square c 2 s of dynamical DE has to be non-negative, Here, we follow the quintessence motivation [58,63,62] and we assume c 2 s = 1. Now we apply the general equations (33) and (34) to each of the dark components. For the CDM component we have,…”

“…An important feature of this class of models is that such interaction implies the existence of DE perturbations even in the case where w = −1. This type of models has been extensively studied in the literature [21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39] as a simple and viable alternative to the standard cosmological model, and there are arguments that indicate that it is not correct to ignore this interaction [40,41] or to ignore the DE perturbations in dynamic DE models [42]. Recent studies indicate some remarkable observational aspects of these interacting models [43,44,45].…”

Null test for interactions in the dark sector

“…1-4, and references therein], hoping to shed light on the nature of the dark sector. In this context, an important topic of research that has been extensively explored relies on considering some specific models for this interaction between the dark components in order to assess its cosmological consequences [5][6][7][8][9][10][11].…”

Listening to the sound of dark sector interactions with gravitational wave standard sirens

“…1 There exist a plethora of models featuring DM-DE interactions, usually referred to as interacting dark energy (IDE) models, most of which phenomenological in nature. For an incomplete selection of works examining IDE models from the modelbuilding, theoretical, and observational perspectives, see for instance [32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,…”