Related papers: A critical value for dark energy
Recent results have suggested that the density of baryons in the Universe, OmegaB, is much more uncertain than previously thought, and may be significantly higher. We demonstrate that a higher OmegaB increases the viability of…
We use the observed evolution of the galaxy cluster X-ray integral temperature distribution function between z=0.05 and z=0.32 in an attempt to constrain the value of the density parameter, Omega_0, for both open and spatially-flat…
We discuss models for the cosmological dark sector in which the energy density of a scalar field approximates Einstein's cosmological constant and the scalar field value determines the dark matter particle mass by a Yukawa coupling. A model…
We study constraints that anticipated DEEP survey galaxy counts versus redshift data will place on cosmological model parameters in models with and without a constant or time-variable cosmological constant $\Lambda$. This data will result…
Observations of clusters of galaxies that gravitationally lens faint background galaxies can probe the amount and the equation of state, $\5$, of the dark energy (quintessence) in the universe. Provided that the mass profile and the mass…
The case grows ever stronger that the average density of matter, ordinary and dark, is less than the critical density required for a flat universe. However, most of determinations of the mass density have been dynamical, hence sensitive…
We examine a dark energy model where a scalar unparticle degree of freedom plays the role of quintessence. In particular, we study a model where the unparticle degree of freedom has a standard kinetic term and a simple mass potential, the…
The unparticle has been suggested as a candidate of dark matter. We investigated the growth rate of the density perturbation for the unparticle dark matter in the flat Universe. First, we consider the model in which unparticle is the sole…
We perform a detailed forecast on how well a {\sc Euclid}-like survey will be able to constrain dark energy and neutrino parameters from a combination of its cosmic shear power spectrum, galaxy power spectrum, and cluster mass function…
The dynamics of our universe is characterised by the density parameters for cosmological constant ($\Omega_V$), nonbaryonic darkmatter($\Omega_{\rm wimp}$), radiation ($\Omega_R$) and baryons ($\Omega_B$). To these parameters -- which…
One of the great scientific enigmas still unsolved, the existence of dark matter, is reviewed. Simple gravitational arguments imply that most of the mass in the Universe, at least 90%, is some (unknown) non-luminous matter. Some particle…
A precise measurement of the curvature of the Universe is of primeval importance for cosmology since it could not only confirm the paradigm of primordial inflation but also help in discriminating between different early Universe scenarios.…
A new dark energy model called "ghost dark energy" was recently suggested to explain the observed accelerating expansion of the universe. This model originates from the Veneziano ghost of QCD. The dark energy density is proportional to…
The Phenomenologically Emergent Dark Energy model, a dark energy model with the same number of free parameters as the flat $\Lambda$CDM, has been proposed as a working example of a minimal model which can avoid the current cosmological…
The critical issue in cosmology today lies in determining if the cosmological constant is the underlying ingredient of dark energy. Our profound lack of understanding of the physics of dark energy places severe constrains on our ability to…
Measurements suggest that our universe has a substantial dark energy component. The most recent data on type Ia supernovae give a dark energy density which is in good agreement with other measurements if the dark energy is assumed to be a…
Using cosmological relativity theory, we derive the formula for the cosmological redshift written explicitly in terms of 1 - "Omega", where "Omega" = "rho"/"rho"_c is the ratio of the average mass density to the critical "closure" density.…
In this paper a new theory of Dark Matter is proposed. Experimental analysis of several Galaxies show how the non-gravitational contribution to galactic Velocity Rotation Curves can be interpreted as that due to the Cosmological Constant…
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…
To explore whether there is new physics going beyond the standard cosmological model or not, we constrain seven cosmological models by combining the latest and largest Pantheon Type Ia supernovae sample with the data combination of baryonic…