Related papers: Dark Energy Induced Anisotropy in Cosmic Expansion
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…
We review current observations of the homogeneous cosmological expansion which, because they measure only kinematic variables, cannot determine the dynamics driving the recent accelerated expansion. The minimal fit to the data, the flat…
The bulk viscosity of cosmological fluid and the creation of cold dark matter both result in the generation of irreversible entropy (related to dissipative processes) in a homogeneous and isotropic universe. To consider such effects, the…
If the dark energy equation of state is anisotropic, the expansion rate of the universe becomes direction-dependent at late times. We show that such models are not only cosmologically viable but that they could explain some of the observed…
Physics invites the idea that space contains energy whose gravitational effect approximates that of Einstein's cosmological constant, Lambda; nowadays the concept is termed dark energy or quintessence. Physics also suggests the dark energy…
In trying to explain the present accelerated expansion of the universe in the light of a five-dimensional Brans-Dicke theory, it is found that the fifth dimension itself here acts as a source of dark energy. It may be taken as a…
The discovery of accelerated cosmic expansion implies that, in addition to the attractive gravity of matter, there exists in our universe some other form of energy (dark energy or cosmological constant) producing a repulsive force. The…
Dark energy can be characterized by a canonical scalar field, known as quintessence. Quintessence allows for a dynamical equation of state $-1 \le \omega \le -\frac{1}{3}$. A previous study by Oikonomou and Chatzarakis have shown that a…
We review the evidence for recently accelerating cosmological expansion or "dark energy", either a negative pressure constituent in General Relativity (Dark Energy) or modified gravity (Dark Gravity), without any Dark Energy constituent. If…
Many candidate models for dark energy are based on the existence of a classical scalar field. In the context of Quantum Field Theory (QFT), we briefly discus the condensation of such a field from a light quantum scalar field produced by…
It is proposed that dark energy may become dominant over standard matter due to universe expansion (curvature decrease). Two models: non-linear gravity-matter system and modified gravity may provide the effective phantom or effective…
This thesis is dedicated to studying cosmological inflation, which is a period of accelerated expansion in the very early Universe that is required to explain the observed anisotropies in the cosmic microwave background. Inflation, when…
This review considers the theoretical approaches to the understanding of dark energy which comprises approximately 68\% of the energy of our Universe and explains an acceleration in its expansion. Following a discussion of the main approach…
We investigate whether interaction between massive neutrinos and quintessence scalar field is the origin of the late time accelerated expansion of the universe. We present explicit formulas of the cosmological linear perturbation theory in…
The origin of accelerating expansion of the Universe is one the biggest conundrum of fundamental physics. In this paper we review vacuum energy issues as the origin of accelerating expansion - generally called dark energy - and give an…
In this article, we investigate the mechanism of cosmological expansion and inflation by modeling dark energy as a four-dimensional continuous medium, with its elastic deformation described by a four-dimensional vector field. We demonstrate…
One of the major problems in cosmology today is to explain the observed acceleration of the universe. The present observational data are consistent with the simplest solution to this problem, which is based on the vacuum energy. A decaying…
Observational evidence indicating that the expansion of the universe is accelerating has surprised cosmologists in recent years. Cosmological models have sought to explain this acceleration by incorporating `dark energy', of which the…
It is assumed that the dark energy observed today is frozen as a result of a phase transition involving the source of that energy. Postulating that the dark energy de-coherence which results from this phase transition drives statistical…
The accelerating expansion of the universe is the most surprising cosmological discovery in many decades. In this short review, we briefly summarize theories for the origin of cosmic acceleration and the observational methods being used to…