Related papers: Generalized phantom energy
A cosmology with the growing cosmological term is considered. If there is no exchange of energy between vacuum and matter components, the requirement of general covariance implies the time dependence of the gravitational constant $G$.…
In this comment we discuss big rip singularities occurring in typical phantom models by violation of the weak energy condition. After that, we compare them with future late-time singularities arising in models where the scale factor ends in…
This paper focuses on developing a generalized ghost dark energy model $f\mathcal{(Q,T)}$ through the correspondence scheme for a non-interacting scenario involving pressureless matter and a power-law scale factor. We analyze the…
A modified Friedmann equation which arises in an extension of general relativity which accommodates a time-dependent fundamental length $L(t)$ leads to cosmological models where the scale factor diverges with an essential singularity at a…
By studying a modified Friedmann equation which arises in an extension of general relativity which accommodates a time-dependent fundamental length $L(t)$, we consider cosmological models where the scale factor diverges with an essential…
As it follows from the classical analysis, the typical final state of the dark energy universe where dominant energy condition is violated is finite time, sudden future singularity (Big Rip). For a number of dark energy universes (including…
The cosmic time dependencies of $G$, $\alpha$, $\hbar$ and of Standard Model parameters like the Higgs vev and elementary particle masses are studied in the framework of a new dark energy interpretation. Due to the associated time variation…
We construct phantom energy models with the equation-of-state parameter $w$ such that $w<-1$, but finite-time future singularity does not occur. Such models can be divided into two classes: (i) energy density increases with time ("phantom…
In this work, we investigate cosmologies where the gravitational constant varies in time, with the aim of explaining the accelerated expansion without a cosmological constant. We achieve this by considering a phenomenological extension to…
The acceleration of the universe can be explained either through dark energy or through the modification of gravity on large scales. In this paper we investigate modified gravity models and compare their observable predictions with dark…
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…
We outline a new model in which generalised uncertainty relations, that govern the behaviour of microscopic world, and dark energy, that determines the large-scale evolution of the Universe, are intrinsically linked via the quantum…
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…
We consider the generalized particle dynamics, proposed by us, in brane world formalisms for an asymptotically anti de Sitter background. The present framework results in a new model that accounts for the late acceleration of the universe.…
Quantum fluctuations of a real massless scalar field are studied in the context of the Generalized Uncertainty Principle (GUP). The dynamical finite vacuum energy is found in spatially flat Friedmann-Robertson- Walker (FRW) spacetime which…
Phantom energy which violates the dominant-energy condition and is not excluded by current constraints on the equation of state may be dominating the evolution of the universe now. It has been pointed out that in such a case the fate of the…
We generalize the cosmic energy equation to the case when massive particles interact via a modified gravitational potential of the form phi(a, r), which is allowed to explicitly depend upon the cosmological time through the expansion factor…
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…
We propose the Gauss-Bonnet dark energy model inspired by string/M-theory where standard gravity with scalar contains additional scalar-dependent coupling with Gauss-Bonnet invariant. It is demonstrated that effective phantom (or…
This paper aims to develop non-interacting ghost dark energy and generalized ghost dark energy models within the framework of $f(Q)$ theory using the correspondence scheme. We use pressureless matter and a power-law scale factor. The cosmic…