Related papers: Cosmological zoo -- accelerating models with dark …
Recent measurements of distant type Ia supernovae (SNIa) as well as other observations indicate that our universe is in accelerating phase of expansion. In principle there are two alternative explanation for such an acceleration. While in…
The current observations are usually explained by an accelerating expansion of the present universe. However, with the present quality of the supernovae Ia data, the allowed parameter space is wide enough to accommodate the decelerating…
It was first observed at the end of the last century that the universe is presently accelerating. Ever since, there have been several attempts to explain this observation theoretically. There are two possible approaches. The more…
In this article we review the discovery of the accelerating universe using type Ia supernovae. We then outline ways in which dark energy - component that causes the acceleration - is phenomenologically described. We finally describe…
The current expansion of the Universe has been observed to be accelerating, and the widely accepted spatially-flat concordance model of general relativistic cosmology attributes this phenomenon to a constant dark energy, a cosmological…
A range of cosmological observations demonstrate an accelerated expansion of the Universe, and the most likely explanation of this phenomenon is a cosmological constant. Given the importance of understanding the underlying physics, it is…
We revisit a cosmological model where dark matter (DM) and dark energy (DE) follow barotropic equations of state, allowing deviations from the standard $\Lambda$CDM framework (i.e. $w_{dm} \neq 0$, $w_{de} \neq -1$), considering both flat…
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…
We explore the idea that cosmic acceleration may be a byproduct of late-time effects like structure formation in two steps. First, we consider the equation of state for an inhomogeneous cosmic fluid, which may lead to a Gedanken-model for…
Is it possible that the current cosmic accelerating expansion will turn into a decelerating one? Can this transition be realized by some viable theoretical model that is consistent with the standard Big Bang cosmology? We study a class of…
The discovery ten years ago that the expansion of the Universe is accelerating put in place the last major building block of the present cosmological model, in which the Universe is composed of 4% baryons, 20% dark matter, and 76% dark…
Observations conducted over the last few decades show that the expansion of the Universe is accelerating. In the standard model of cosmology, this accelerated expansion is attributed to a dark energy in the form of a cosmological constant.…
The dynamical aspect of accelerating cosmological model has been studied in this paper in the context of modified symmetric teleparallel gravity, the $f(Q)$ gravity. Initially, we have derived the dynamical parameters for two well known…
Recent astronomical observations of distant supernovae light-curves suggest that the expansion of the universe has recently begun to accelerate. Acceleration is created by an anti-gravitational repulsive stress, like that produced by a…
The current accelerating phase of the evolution of the universe is considered by constructing most economical cosmic models that use just general relativity and some dominating quantum effects associated with the probabilistic description…
An alternative to dark energy as an explanation for the present phase of accelerated expansion of the Universe is that the Friedmann equation is modified, e.g. by extra dimensional gravity, on large scales. We explore a natural…
According to the standard $\Lambda$CDM model, the accelerated expansion of the Universe will go on forever. Motivated by recent observational results, we explore the possibility of a finite phase of acceleration which asymptotically…
A phenomenological approach is proposed to the problem of universe accelerated expansion and of the dark energy nature. A general class of models is introduced whose energy density depends on the redshift $z$ in such a way that a smooth…
Homogeneous cosmological solutions are obtained in five dimensional space time assuming equations of state $ p = k\rho $ and $ p_{5}= \gamma\rho$ where p is the isotropic 3 - pressure and $p_{5}$, that for the fifth dimension. Using…
Recent observations of the Universe have led to a conclusion suppressing an up-to-now supposed deceleration of the Universe caused by attractive gravitational forces. Contrary, there is a renaissance of the cosmological member lambda and…