scispace - formally typeset
Search or ask a question
Topic

Deceleration parameter

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


Papers
More filters
Posted Content
TL;DR: In this article, the authors estimate the expected uncertainty in the Hubble diagram determination of q_0 due to weak lensing by structure in the universe, which stochastically shifts the apparent brightness of distant standard candles.
Abstract: On-going projects to discover Type Ia supernovae at redshifts z = 0.3 - 1, coupled with improved techniques to narrow the dispersion in SN Ia peak magnitudes, have renewed the prospects for determining the cosmic deceleration parameter q_0. We estimate the expected uncertainty in the Hubble diagram determination of q_0 due to weak lensing by structure in the universe, which stochastically shifts the apparent brightness of distant standard candles. Although the results are sensitive to the density power spectrum on small scales, the induced flux dispersion sigma_m 1.

19 citations

Journal ArticleDOI
TL;DR: In this paper, a flat Friedmann-Robertson-Walker universe with dark matter and viscous new holographic dark energy was studied and the evolution of cosmological quantities such as scale factor, deceleration parameter and transition redshift was analyzed.
Abstract: In this work, we study a flat Friedmann–Robertson–Walker universe filled with dark matter and viscous new holographic dark energy. We present four possible solutions of the model depending on the choice of the viscous term. We obtain the evolution of the cosmological quantities such as scale factor, deceleration parameter and transition redshift to observe the effect of viscosity in the evolution. We also emphasis upon the two independent geometrical diagnostics for our model, namely the statefinder and the Om diagnostics. In the first case we study new holographic dark energy model without viscous and obtain power-law expansion of the universe which gives constant deceleration parameter and statefinder parameters. In the limit of the parameter, the model approaches to $$\Lambda CDM$$ model. In new holographic dark energy model with viscous, the bulk viscous coefficient is assumed as $$\zeta =\zeta _{0}+\zeta _{1}H$$ , where $$\zeta _{0}$$ and $$\zeta _{1}$$ are constants, and H is the Hubble parameter. In this model, we obtain all possible solutions with viscous term and analyze the expansion history of the universe. We draw the evolution graphs of the scale factor and deceleration parameter. It is observed that the universe transits from deceleration to acceleration for small values of $$\zeta $$ in late time. However, it accelerates very fast from the beginning for large values of $$\zeta $$ . By illustrating the evolutionary trajectories in $$r-s$$ and $$r-q$$ planes, we find that our model behaves as an quintessence like for small values of viscous coefficient and a Chaplygin gas like for large values of bulk viscous coefficient at early stage. However, model has close resemblance to that of the $$\Lambda CDM$$ cosmology in late time. The $$ Om$$ has positive and negative curvatures for phantom and quintessence models, respectively depending on $$\zeta $$ . Our study shows that the bulk viscosity plays very important role in the expansion history of the universe.

19 citations

Journal ArticleDOI
TL;DR: In this paper, the authors presented numerical solutions to the problem of infall of matter into clusters of galaxies, assuming that the universe can be described by a Friedmann cosmological model with a Hubble constant 50 km/s/Mpc.
Abstract: Numerical solutions to the problem of infall of matter into clusters of galaxies are presented. It is assumed that the universe can be described by a Friedmann cosmological model with a Hubble constant 50 km/s/Mpc. It is found that physically reasonable models having a deceleration parameter of 1/2 lead to excessive X-ray emission from clusters of galaxies. Models including a heat flux due to thermal conduction, heating of the intracluster medium by galaxy motions, and a gas outflow from the galaxies in the cluster are discussed, and the results are compared with the observational data in both the X-ray and radio bands. It is concluded that the density parameter must be less than 0.2 in order that the predicted X-ray emission not exceed that observed. No models have been found which give a good description of the observed cluster X-ray sources, with the exception of a fully adiabatic model in a high-density universe.

19 citations

Journal ArticleDOI
TL;DR: In this paper, the interaction rate between dark energy and dark matter has been reconstructed for three different parameterizations of the deceleration parameter, which is based on the holographic dark energy model with Hubble horizon as the infrared cutoff.
Abstract: The present work is based on the holographic dark energy model with Hubble horizon as the infrared cut-off. The interaction rate between dark energy and dark matter has been reconstructed for three different parameterizations of the deceleration parameter. Observational constraints on the model parameters have been obtained by maximum likelihood analysis using the observational Hubble parameter data (OHD), type Ia supernovab data (SNe), baryon acoustic oscillation data (BAO) and the distance prior of cosmic microwave background (CMB) namely the CMB shift parameter data (CMBShift). The interaction rate obtained in the present work remains always positive and increases with expansion. It is very similar to the result obtained by Sen and Pavon [1] where the interaction rate has been reconstructed for a parametrization of the dark energy equation of state. Tighter constraints on the interaction rate have been obtained in the present work as it is based on larger data sets. The nature of the dark energy equation of state parameter has also been studied for the present models. Though the reconstruction is done from different parametrizations, the overall nature of the interaction rate is very similar in all the cases. Different information criteria and the Bayesian evidence, which have been invoked in the context of model selection, show that the these models are at close proximity of each other.

19 citations

Journal ArticleDOI
16 May 2022
TL;DR: In this paper , a holographic dark energy scenario based on Kaniadakis entropy was constructed, which is a generalization of Boltzmann-Gibbs entropy that arises from relativistic statistical theory and is characterized by a single parameter K which quantifies the deviations from standard expressions, and the future event horizon as the Infrared cutoff.
Abstract: Abstract We construct a holographic dark energy scenario based on Kaniadakis entropy, which is a generalization of Boltzmann-Gibbs entropy that arises from relativistic statistical theory and is characterized by a single parameter K which quantifies the deviations from standard expressions, and we use the future event horizon as the Infrared cutoff. We extract the differential equation that determines the evolution of the effective dark energy density parameter, and we provide analytical expressions for the corresponding equation-of-state and deceleration parameters. We show that the universe exhibits the standard thermal history, with the sequence of matter and dark-energy eras, while the transition to acceleration takes place at $$z\approx 0.6$$ z 0.6 . Concerning the dark-energy equation-of-state parameter we show that it can have a rich behavior, being quintessence-like, phantom-like, or experience the phantom-divide crossing in the past or in the future. Finally, in the far future dark energy dominates completely, and the asymptotic value of its equation of state depends on the values of the two model parameters.

19 citations


Network Information
Related Topics (5)
General relativity
29K papers, 810.8K citations
92% related
Gravitation
29.3K papers, 821.5K citations
90% related
Black hole
40.9K papers, 1.5M citations
89% related
Dark matter
41.5K papers, 1.5M citations
86% related
Gauge theory
38.7K papers, 1.2M citations
84% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023120
2022210
2021128
2020116
2019107
201892