Related papers: Dark energy perturbations and a possible solution …
In this work, we further investigate the family of $f(R)$ dark energy models that can exactly mimic the same background expansion history as that of the $\Lambda$CDM model. We study the large scale structure in the $f(R)$ gravity using the…
A cosmological model of dark energy interacting with dark matter and another general component of the universe is investigated. We found general constraints on these models imposing an accelerated expansion. The same is also studied in the…
Interacting dark energy and the holographic principle offer a possible way of addressing the cosmic coincidence problem as well as accounting for the size of the dark energy component. The equilibrium points of the Friedmann equations which…
In this first paper we discuss the linear theory and the background evolution of a new class of models we dub SCDEW: Strongly Coupled DE, plus WDM. In these models, WDM dominates today's matter density; like baryons, WDM is uncoupled. Dark…
The observational fact that the present values of the densities of dark energy and dark matter are of the same order of magnitude, $\rho_{de0}/\rho_{dm0} \sim \mathcal{O}(1)$, seems to indicate that we are currently living in a very special…
The strong CP problem was solved by Peccei & Quinn by introducing axions, which are a viable candidate for DM. Here the PQ approach is modified so to yield also Dark Energy (DE), which arises in fair proportions, without tuning any extra…
We explore the physics of a gas of particles interacting with a condensate that spontaneously breaks Lorentz invariance. The equation of state of this gas varies from 1/3 to less than -1 and can lead to the observed cosmic acceleration. The…
We explore an autonomous system analysis of dark energy models with interactions between dark energy and cold dark matter in a general systematic approach to cosmological fluids. We investigate two types of models such as local and…
We propose the Locally Pumped Dark Energy (LPDE) mechanism in which cosmic acceleration is triggered by the emergence of non-linear dark matter structure. In an effective-field-theory description, coarse-graining over the density contrast…
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…
The nature of dark energy (DE) remains elusive, even though it constitutes the dominant energy-density component of the Universe and drives the late-time acceleration of cosmic expansion. By combining measurements of the expansion history…
We study cosmological perturbations in a model of unified dark matter and dark energy with a sharp transition in the late-time universe. The dark sector is described by a dark fluid which evolves from an early stage at redshifts $z > z_C$…
We present a cosmological model constituted by three perfect fluids, cold dark matter, vacuum energy and radiation, which interacting with each other lead to an equivalent model of three self-preserved fluids that can be identified with the…
A rare coincidence of scales in standard particle physics is needed to explain why $\Lambda$ or the negative pressure of cosmological dark energy (DE) coincides with the positive pressure $P_0$ of random motion of dark matter (DM) in bright…
Within the framework of spatially covariant theories, we propose a general model for dark energy (DE) in which the cosmological background and perturbations are independently controlled by different sets of coefficients, and the equation of…
The high-quality cosmological data, which became available in the last decade, have thrusted upon us a rather preposterous composition for the universe which poses one of the greatest challenges theoretical physics has ever faced: the…
A late accelerated expansion of the Universe is obtained from non-relativistic particles with a short-range attractive interaction, and low enough temperature to produce a Bose-Einstein condensate; by considering coupled dark-energy…
We study some properties of the dark degeneracy, which is the fact that what we measure in gravitational experiments is the energy momentum tensor of the total dark sector, and any split into components (as in dark matter and dark energy)…
This paper introduces the class of omnipotent dark energy (DE) models characterized by nonmonotonic energy densities that are capable of attaining negative values with corresponding equation of state parameters featuring phantom divide line…
We search for physically consistent realizations of evolving dark energy suggested by the cosmological fit of DESI, Planck and Supernovae data. First we note that any lagrangian description of the standard Chevallier-Polarski-Linder (CPL)…