Deceleration parameter

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

A better way to reconstruct dark energy models

Abstract: To reconstruct dark energy models the redshift z eq , marking the end of radiation era and the beginning of matter-dominated era, can play a role as important as z t , the redshift at which deceleration parameter experiences a signature flip. To implement the idea we propose a variable equation of state for matter that can bring a smooth transition from radiation to matter-dominated era in a single model. A popular Λ∝ ρ dark energy model is chosen for demonstration but found to be unacceptable. An alternative Λ∝ ρ a 3 model is proposed and found to be more close to observation.

Testing lambda and the limits of cosmography with the union2.1 supernova compilation

Abstract: We present a cosmographic study designed to test the simplest type of accelerating cosmology: a flat universe with matter and a cosmological constant (Λ). Hubble series expansions are fit to the SCP Union2.1 supernova data set to estimate the Hubble Constant (H0), the deceleration parameter (q0), and the jerk parameter (j0). Flat ΛCDM models always require providing a single-parameter test of the entire paradigm. Because of convergence issues for we focus on expansions using the newer redshift variable y; and to estimate the effects of "model-building uncertainties"—the dependence of the output results upon the fitting function and parameters used—we perform fits using five different distance indicator functions, and four different polynomial orders. We find that one cannot yet use the supernova data to reliably obtain more than four cosmological parameters; and that cosmographic estimates of j0 remain dominated by model-building uncertainties, in conjunction with statistical and other error sources. While remains consistent with Union2.1, the most restrictive bound that we can place is To test the future prospects of cosmography with new standard candle data, ensembles of mock supernova data sets are created; and it is found that the best way to reduce model-building uncertainties on lower-order Hubble parameters (such as ) is by limiting the redshift range of the data. Thus more and better data, not higher-redshift data, are needed to sharpen cosmographic tests of flat ΛCDM.

Power-Law and Logarithmic Entropy-Corrected Ricci Viscous Dark Energy and Dynamics of Scalar Fields

Abstract: In this work, I consider the logarithmic-corrected and the power-law corrected versions of the holographic dark energy (HDE) model in the non-flat FRW universe filled with a viscous Dark Energy (DE) interacting with Dark Matter (DM). We propose to replace the infra-red cut-off with the inverse of the Ricci scalar curvature $R$. I obtain the equation of state (EoS) parameter $\omega_{\Lambda}$, the deceleration parameter $q$ and the evolution of energy density parameter $\Omega_D'$ in the presence of interaction between DE and DM for both corrections. I study the correspondence of the logarithmic entropy corrected Ricci Dark Dnergy (LECRDE) and power-law entropy corrected Ricci Dark Energy (PLECRDE) models with the the Modified Chaplygin Gas (MCG) and some scalar fields including tachyon, K-essence, dilaton and quintessence. I also make comparisons with previous results.

Bianchi Type VIo Magnetized Anisotropic Dark Energy Models with Constant Deceleration Parameter

Abstract: The paper deals with an anisotropic Bianchi type VIo cosmological model with variable ω in the presence and absence of magnetic field of energy density ρB. A special law of variation for Hubble’s parameter proposed by Berman (Nuovo Cimento B 74:182, 1983) has been utilized to solve the field equations.