Related papers: Perturbations In Some Dark Energy Models
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…
Recent astrophysical observations indicate that the universe is composed of a large amount of dark energy (DE) responsible for an accelerated expansion of the universe, along with a sizeable amount of cold dark matter (CDM), responsible for…
The observed late-time acceleration of the cosmic expansion constitutes a fundamental problem in modern theoretical physics and cosmology. In an attempt to weight the validity of a large number of dark energy models, I use the recent…
A model for a flat homogeneous and isotropic Universe composed of dark energy, dark matter, neutrinos, radiation and baryons is analyzed. The fields of dark matter and neutrinos are supposed to interact with the dark energy. The dark energy…
Taking up four model universes we study the behaviour and contribution of dark energy to the accelerated expansion of the universe, in the modified scale covariant theory of gravitation. Here, it is seen that though this modified theory may…
The mysterious `dark energy' needed to explain the current observations, poses a serious confrontation between fundamental physics and cosmology. The present crisis may be an outcome of the (so far untested) prediction of the general theory…
The existence of dark matter and dark energy in cosmology is implied by various observations, however, they are still unclear because they have not been directly detected. In this Letter, an unified model of dark energy and dark matter that…
A web of interlocking observations has established that the expansion of the Universe is speeding up and not slowing, revealing the presence of some form of repulsive gravity. Within the context of general relativity the cause of cosmic…
Dynamical wave function collapse models entail the continuous liberation of a specified rate of energy arising from the interaction of a fluctuating scalar field with the matter wave function. We consider the wave function collapse process…
The main sources of information energy in the universe are shown to be stellar heated gas and dust and black holes. Information energy has properties similar to dark energy with a significant energy density that has remained nearly constant…
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…
Here, creation of the universe is obtained only from gravity sector. The dynamical universe begins with two basic ingredients (i) vacuum energy, also called dark energy (as vacuum energy is not observed) and (ii) background radiation. These…
The evolution of matter density perturbations in two-component model of the Universe consisting of dark energy (DE) and dust-like matter (M) is considered. We have analyzed it for two kinds of DE with $\omega\ne -1$: a) unperturbed energy…
In a four dimensional manifold formalism we study the evolutionary behavior as well as the ultimate fate of the universe, in the course of which the contribution of dark energy in these phases are investigated. At one stage we get a…
It is now a well established fact based on several observations that we live in a Universe dominated by dark energy. The most natural candidates for dark energy are fields in curved space-time. We develop the formalism to study the…
In the past few years, a possibility is investigated, where curvature itself behaves as a source of dark energy. So, it is natural to think whether curvature can produce dark matter too. It is found that, at classical level,…
It is argued that dark energy -or something dynamically equivalent at the background level- is necessary if the expanding universe is to behave as an ordinary macroscopic system; that is, if it is to tend to some thermodynamic equilibrium…
The dark sector of the Universe need not be completely separable into distinct dark matter and dark energy components. We consider a model of early dark energy in which the dark energy mimics a dark matter component in both evolution and…
In this work it is investigated the evolution of a Universe where a scalar field, non-minimally coupled to space-time curvature, plays the role of quintessence and drives the Universe to a present accelerated expansion. A non-relativistic…
Over the last few years a certain class of dark-energy models decaying inversely proportional to the square of the horizon distance emerged on the basis either of Heisenberg uncertainty relations or of the uncertainty relation between the…