Deceleration parameter

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

Local determination of the Hubble constant and the deceleration parameter

Abstract: The authors provide a determination of the Hubble constant based on the local universe and independent of any cosmological assumptions. The result is in strong tension with what the cosmic microwave background predicts assuming the standard model of cosmology is valid

Acceleration of the Universe with a simple trigonometric potential

Abstract: In this paper, we investigate the quintessence model with a minimally coupled scalar field in the context of recent supernovae observations. By choosing a particular form of the deceleration parameter q, which gives an early deceleration and late time acceleration for the dust dominated model, we show that this sign flip in q can be obtained by a simple trigonometric potential. The early matter dominated model expands with q = 1/2 as desired and enters a negative q phase quite late during the evolution.

Dark energy models with variable equation of state parameter

Abstract: Two phenomenological variable Λ models, viz.Λ ~ (ȧ/a)2 and Λ ~ ρ, have been studied under the assumption that the equation of state parameter ω is a function of time. The selected Λ models are found to be equivalent both in four and five dimensions. The possibility of signature flip of the deceleration parameter is also shown.

Holographic f(T)-gravity model with power-law entropy correction

Abstract: Using the correspondence between the $f(T)$-gravity model and the holographic dark energy model with the power-law entropy correction, we reconstruct the holographic $f(T)$-gravity model with the power-law entropy correction. We fit the model parameters by using the latest observational data including type Ia supernovae, baryon acoustic oscillations, cosmic microwave background, and Hubble parameter data. We also check the viability of our model using a cosmographic analysis approach. Using the best-fit values of the model, we obtain the evolutionary behavior of the effective torsion equation-of-state parameter of the power-law entropy-corrected holographic $f(T)$-gravity model, as well as the deceleration parameter of the Universe. We also investigate different energy conditions in our model. Furthermore, we examine the validity of the generalized second law of gravitational thermodynamics. Finally, we point out the growth rate of the matter density perturbation in our model. We conclude that in the power-law entropy-corrected holographic $f(T)$-gravity model, the Universe begins a matter-dominated phase and approaches a de Sitter regime at late times, as expected. It also can justify the transition from the quintessence state to the phantom regime in the near past, as indicated by recent observations. Moreover, this model is consistent with current data, it passes the cosmographic test, and it fits the data of the growth factor as well as the $\ensuremath{\Lambda}\mathrm{CDM}$ model.