Deceleration parameter

About: Deceleration parameter is a research topic. Over the lifetime, 1776 publications have been published within this topic receiving 89440 citations.

Behaviour of the cosmological model with variable deceleration parameter

Abstract: We consider the Bianchi type-VI0 massive string universe with decaying cosmological constant $\Lambda$ . To solve Einstein's field equations, we assume that the shear scalar is proportional to the expansion scalar and that the deceleration parameter q is a linear function of the Hubble parameter H, i.e., $q=\alpha +\beta H$ , which yields the scale factor $a = e^{\frac{1}{\beta}\sqrt{2\beta t+k_{1}}}$ . The model expands exponentially with cosmic time t. The value of the cosmological constant $\Lambda$ is small and positive. Also, we discuss physical parameters as well as the jerk parameter j, which predict that the universe in this model originates as in the $\Lambda$ CDM model.

Modeling of Accelerating Universe with Bulk Viscous Fluid in Bianchi V Space‐Time

Abstract: In this paper, we have investigated a bulk viscous anisotropic Universe and constrained its model parameters with recent $H(z)$ and Pantheon compilation data. Using cosmic chronometric technique, we estimate the present value of Hubble's constant as $H_{0} = 69.39 \pm 1.54~km~s^{-1}Mpc^{-1}$, $70.016 \pm 1.65~km~s^{-1}Mpc^{-1}$ and $69.36 \pm 1.42~km~s^{-1}Mpc^{-1}$ by bounding our derived model with recent $H(z)$ data, Pantheon and joint $H(z)$ and Pantheon data respectively. The present age of the Universe is specified as $t_0= 0.9796H_0^{-1}\sim 13.79$ Gyrs. The model favours a transitioning Universe with the transition red-shift as $z_{t} = 0.73$. We have reconstructed the jerk parameter using the observational data sets. From the analysis of the jerk parameter, it is observed that, our derived model shows a marginal departure from the concordance $\Lambda$CDM model.

Analysis of Theory Corresponding to NADE and NHDE

Abstract: We develop the connection of theory with new agegraphic and holographic dark energy models. The function is reconstructed regarding the theory as an effective description for these dark energy models. We show the future evolution of and conclude that these functions represent distinct pictures of cosmological eras. The cosmological parameters such as equation of state parameter, deceleration parameter, statefinder diagnostic, and analysis are investigated which assure the evolutionary paradigm of .

Exact Kantowski-Sachs Anisotropic Dark Energy Cosmological Models in Brans Dicke Theory of Gravitation

Abstract: The main purpose of this paper is to explore the solution of Exact Kantowski-Sach cosmological models by using the Brans Dicke Theory of gravitation in the background of anisotropic dark energy. In order to obtain different physically variable models of the universe we have assumed the special law of variation of Hubbles parameter proposed by Berman (Nuovo Cimento B 74:182, 1983) which yields constant deceleration parameter and power law relation between average scale factor R and scalar field f, which has already been used by Johri and Desikan in RW Brans Dicke models. Some physical and geometrical consequences of the models have been carried out by using some physical quantities.

Some remarks on luminosity distance and nucleosynthesis in higher dimensional cosmology

Abstract: Using a previous cosmological solution of the present author, the behavior of luminosity distance is analyzed in multidimensional spacetime. It is observed that the de Sitter spacetime sets an upper limit to the absolute distance of any cosmological source where the generally accepted value of the deceleration parameter q(0) greater than -1 is taken. This generalizes an earlier result of Barnes to higher dimensions. Further, an attempt is made to investigate, in brief, the phenomenon of nucleosynthesis in the early universe. While it is premature to make a definite statement in this regard, it is found that there may be significant differences, in principle at least, from the analogous situation in four-dimensional spacetime. 15 refs.