Related papers: LXCDM cosmologies: solving the cosmological coinci…
In this paper we investigate the evolution of the viscous dark energy (DE) interacting with the dark matter (DM) in the Einstein cosmology model. Using the linearizing theory of the dynamical system, we find, in our model, there exists a…
The energy densities of dark matter (DM) and dark energy (DE) are of the same order at the present epoch despite the fact that both these quantities have contrasting characteristics and are presumed to have evolved distinctively with cosmic…
The interacting and holographic dark energy models involve two important quantities. One is the characteristic size of the holographic bound and the other is the coupling term of the interaction between dark energy and dark matter. Rather…
Associated with the cosmic acceleration are the old and new cosmological constant problems, recently put into the more general context of the dark energy problem. In broad terms, the old problem is related to an unexpected order of…
It has, quite recently, become fashionable to study a certain class of holographic-inspired models for the dark energy. These investigations have, indeed, managed to make some significant advances towards explaining the empirical data.…
We study a cosmological model in which phantom dark energy is coupled to dark matter by phenomenologically introducing a coupled term to the equations of motion of dark energy and dark matter. This term is parameterized by a dimensionless…
I briefly review the cosmological constant problem and the issue of dark energy (or quintessence). Within the framework of quantum field theory, the vacuum expectation value of the energy momentum tensor formally diverges as $k^4$. A cutoff…
A new bound dark energy, BDE, cosmology has been proposed where the dark energy is the binding energy between light meson fields that condense a few tens of years after the big bang. It is reported that the correct dark energy density…
We study some cosmological constraints on the two phenomenological models of oscillating dark energy. In these scenarios, the equation of state of dark energy varies periodically and may provide a way to unify the early acceleration…
In this paper is proposed a geometric solution to the dark energy, assuming that the space can be divided into regions of size $\sim L_{p}$ and energy $\sim E_{p}$. Significantly this assumption generate a energy density similar to the…
We study the role of the cosmological constant (CC) as a component of dark energy (DE). It is argued that the cosmological term is in general unavoidable and it should not be ignored even when dynamical DE sources are considered. From the…
Recent cosmological observations strongly suggest that the universe is dominated by an unknown form of energy with negative pressure. Why is this dark energy density of order the critical density today? We propose that the dark energy has…
By assuming a phenomenological form for the ratio of the DE and DM densities $\rho_X\propto \rho_{m} a^{\xi}$ (Dalal et al.2001), we discuss the cosmic coincidence problem in light of current observational data. $\xi$ is a key parameter to…
Dark energy models which alter the relative scaling behavior of dark energy and matter could provide a natural solution to the cosmic coincidence problem - why the densities of dark energy and dark matter are comparable today. A generalized…
The problem of dark energy can be roughly stated as the proposition and validation of a cosmological model that can explain the phenomenon of the accelerated expansion of the Universe. This problem is an open discussion topic in modern…
In this work we review briefly the origin and history of the cosmological constant and its recent reincarnation in the form of the dark energy component of the universe. We also comment on the fundamental problems associated to its…
In the standard cosmological model the dark energy (DE) and nonrelativistic (NR) matter densities are observationally determined to be comparable at the present time, in spite of their greatly different evolution histories. This `cosmic…
While $\Lambda$CDM provides a good fit to cosmological data, it fails to address many of the outstanding questions in contemporary cosmology. Chief among these are the Hubble tension and the apparent dynamical nature of dark energy as…
A novel idea is proposed for a natural solution of the dark energy and its cosmic coincidence problem. The existence of local antigravity sources, associated with astrophysical matter configurations distributed throughout the universe, can…
We consider a model of interacting cosmological constant/quintessence, where dark matter and dark energy behave as, respectively, two coexisting phases of a fluid, a thermally excited Bose component and a condensate, respectively. In a…