Related papers: Phantom cosmologies from QCD ghost dark energy
The recently observed accelerated expansion of the universe has put a challenge for its theoretical understanding. As a possible explanation of this, it is considered that the most part of the present universe is filled with a form of…
Considering that the universe is filled with the nonrelativistic matter and dark energy and each component is respectively satisfied with its conservation condition in the absence of their interaction, we give the change rate of the…
We study the late-time cosmological dynamics of a two-field dark energy model consisting of a canonical quintessence scalar field and a phantom scalar field in a spatially flat FLRW universe. The fields are minimally coupled to gravity and…
A two-component fluid representing dark energy is studied. One of the components has a polytropic form, while the other has a barotropic form. Exact solutions are obtained and the cosmological parameters are constrained using supernova type…
Recent determinations of the equation of state of dark energy hint that this may well be of the phantom type, i.e., $w_{de} < -1$. If confirmed by future experiments, this would strongly point to the existence of fields that violate the…
We present here some recent results concerning scalar-tensor Dark Energy models. These models are very interesting in many respects: they allow for a consistent phantom phase, the growth of matter perturbations is modified. Using a…
When taking the holographic principle into account, the vacuum energy will acquire dynamical property that its equation of state is evolving. The current available observational data imply that the holographic vacuum energy behaves as…
We consider a higher dimensional gravity theory with a negative kinetic energy scalar field and a cosmological constant. We find that the theory admits an exact cosmological solution for the scale factor of our universe. It has the feature…
There is compelling evidence that the Universe is undergoing a late phase of accelerated expansion. One of the simplest explanations for this behaviour is the presence of dark energy. A plethora of microphysical models for dark energy have…
We present a comprehensive phase-space analysis of a quadratic dark energy model where the pressure includes a nonlinear term proportional to the square of the energy density. This minimal extension beyond the $\Lambda$CDM framework…
Analyzing quantum cosmological scenarios containing one scalar field with exponential potential, we have obtained a universe model which realizes a classical dust contraction from very large scales, the initial repeller of the model, and…
The consensus of opinion in cosmology is that the Universe is currently undergoing a period of accelerated expansion. With current and proposed high precision experiments it offers the hope of being able to discriminate between the two…
Phantom scalar theories are widely considered in cosmology, but rarely at the quantum level, where they give rise to negative-energy ghost particles. These cause decay of the vacuum into gravitons and photons, violating observational…
We investigate the cosmological evolution of a two-field model of dark energy where one is a dilaton field with canonical kinetic energy and the other is a phantom field with a negative kinetic energy term. A phase-plane analysis shows that…
We perform a detailed investigation of interacting phantom cosmology, by applying the powerful method of dynamical system analysis. We consider two well-studied interaction forms, namely one global and one local one, while the novel…
We perform a detailed phase-space analysis of various phantom cosmological models, where the dark energy sector interacts with the dark matter one. We examine whether there exist late-time scaling attractors, corresponding to an…
The hypothesis is rapidly gaining popularity that the dark energy pervading our universe is extra-repulsive ($-p>\rho$). The density of such a substance(usually called phantom energy) grows with the cosmological expansion and may become…
Phantom cosmology allows to account for dynamics and matter content of the universe tracing back the evolution to the inflationary epoch, considering the transition to the non-phantom standard cosmology (radiation/matter dominated eras) and…
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…
The two most popular candidates for dark energy, i.e. a cosmological constant and quintessence, are very difficult to distinguish observationally, mostly because the quintessence field does not have sizable fluctuations. We study a scalar…