Related papers: Spherical Collapse Model And Dark Energy(I)
The amount and nature of dark energy (DE) can be tightly constrained by measuring the spatial correlation features and evolution of a sample of ~ 100,000 galaxy clusters over the redshift range 0<z < 1.5. Such an X-ray survey will discover…
The recent observational evidences for the present accelerated stage of the Universe have stimulated renewed interest for alternative cosmologies. In general, such models contain an unknown negative-pressure dark component that explains the…
In this work, gravitational collapse of a spherical cloud, consists of both dark matter and dark energy in the form of modified Chaplygin gas is studied. It is found that dark energy alone in the form of modified Chaplygin gas forms black…
In this second paper we present the first Nbody cosmological simulations of strongly coupled Dark Energy models (SCDEW), a class of models that alleviates theoretical issues related to the nature of dark energy. SCDEW models assume a strong…
We perform an empirical consistency test of General Relativity/dark energy by disentangling expansion history and growth of structure constraints. We replace each late-universe parameter that describes the behavior of dark energy with two…
We studied the spherical collapse model in the flat $\Lambda$CDM cosmology and provided exact and analytical formulaes for the calculation of the two important parameters in the application of Press-Schechter theory, the critical density…
A pressureless dark matter component fits well with several cosmological observations. However, there are indications that cold dark matter may encounter challenges in explaining observations at small scales, particularly at galactic…
We generalize the spherical collapse model for the formation of dark matter halos to apply in a universe with arbitrary positive cosmological constant. We calculate the critical condition for collapse of an overdense region and give exact…
Modern Cosmology offers us a great understanding of the universe with striking precision, made possible by the modern technologies of the newest generations of telescopes. The standard cosmological model, however, is not absent of…
We explore the properties of dark energy from recent observational data, including the Gold Sne Ia, the baryonic acoustic oscillation peak from SDSS, the CMB shift parameter from WMAP3, the X-ray gas mass fraction in cluster and the Hubble…
This paper examines the growth of dark matter and dark energy perturbations within a non-canonical scalar field model characterized by an exponential potential. Through dynamical system analysis, we identify critical points and track the…
Holographic dark energy models have been recently suggested which most clearly show that accelerating cosmology appears to be incompatible with mathematically consistent formulations of fundamental theories such as string/M theories. In…
When an open system of classical point particles interacting by Newtonian gravity collapses and relaxes violently, an arbitrary amount of energy may in principle be carried away by particles which escape to infinity. We investigate here,…
We present constraints on extensions of the minimal cosmological models dominated by dark matter and dark energy, $\Lambda$CDM and $w$CDM, by using a combined analysis of galaxy clustering and weak gravitational lensing from the first-year…
We solve analytically and numerically the generalized Einstein equations in scalar-tensor cosmologies to obtain the evolution of dark energy and matter linear perturbations. We compare our results with the corresponding results for…
We estimate the energy release of black hole formation to the intra-cluster medium of the Coma cluster and find that this is comparable to the present day energy content. Therefore an energetic and maybe hydrostatic influence is possible.…
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 pressureless scenario for the Dark Matter (DM) fluid is a widely adopted hypothesis, despite the absence of a direct observational evidence. According to general relativity, the total mass-energy content of a system shapes the…
The influence of the shear stress and angular momentum on the nonlinear spherical collapse model is discussed in the framework of the Einstein-de Sitter (EdS) and $\Lambda$CDM models. By assuming that the vacuum component is not clustering…
I briefly review our current understanding of dark matter and dark energy. The first part of this paper focusses on issues pertaining to dark matter including observational evidence for its existence, current constraints and the `abundance…