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We examine the validity of the $\Lambda$CDM model, and probe for the dynamics of dark energy using latest astronomical observations. Using the $Om(z)$ diagnosis, we find that different kinds of observational data are in tension within the…

Cosmology and Nongalactic Astrophysics · Physics 2017-06-14 Yuecheng Zhang , Hanyu Zhang , Dandan Wang , Yanghan Qi , Yuting Wang , Gong-Bo Zhao

We apply a new non-parametric Bayesian method for reconstructing the evolution history of the equation-of-state $w$ of dark energy, based on applying a correlated prior for $w(z)$, to a collection of cosmological data. We combine the latest…

Cosmology and Nongalactic Astrophysics · Physics 2013-03-20 Gong-Bo Zhao , Robert G. Crittenden , Levon Pogosian , Xinmin Zhang

We consider how well the dark energy equation of state $w$ as a function of red shift $z$ will be measured using current and anticipated experiments. We use a procedure which takes fair account of the uncertainties in the functional…

Astrophysics · Physics 2011-02-01 Amol Upadhye , Mustapha Ishak , Paul J. Steinhardt

Observing dark energy dynamics is the most important aspect of the dark energy research. In this paper we perform an analysis of the constraints on the property of dark energy from the current astronomical observations. We pay particular…

Astrophysics · Physics 2009-11-13 Jun-Qing Xia , Gong-Bo Zhao , Bo Feng , Hong Li , Xinmin Zhang

We place, by the maximum likelihood method, constraints on a variable dark energy model with the equation of state $w=w_0/[1+b\ln (1+z)]^2$ using some recent observational data, including the new Sne Ia data from the SNLS, the size of…

Astrophysics · Physics 2008-11-26 Puxun Wu , Hongwei Yu

We have calculated constraints on the evolution of the equation of state of the dark energy, w(z), from a joint analysis of data from the cosmic microwave background, large scale structure and type-Ia supernovae. In order to probe the…

Astrophysics · Physics 2009-11-10 Steen Hannestad , Edvard Mortsell

In this paper, we combine the the latest observational data, including the WMAP five-year data (WMAP5), the baryon acoustic oscillations (BAO) and type Ia supernovae (SN) "union" compilation, and use the Markov Chain Monte Carlo method to…

Cosmology and Nongalactic Astrophysics · Physics 2010-05-11 Hong Li , Jun-Qing Xia

Data-driven model-independent reconstructions of the dark energy equation of state $w(z)$ are presented using Planck 2015 era CMB, BAO, SNIa and Lyman-$\alpha$ data. These reconstructions identify the $w(z)$ behaviour supported by the data…

Cosmology and Nongalactic Astrophysics · Physics 2017-01-26 S. Hee , J. A. Vázquez , W. J. Handley , M. P. Hobson , A. N. Lasenby

I review the observational prospects to constrain the equation of state parameter of dark energy and I discuss the potential of future imaging and redshift surveys. Bayesian model selection is used to address the question of the level of…

Astrophysics · Physics 2007-05-23 Roberto Trotta

Observational constraints on time-varying dark energy ({\it e.g.}, quintessence) are commonly presented on a $w_0$-$w_a$ plot that assumes the equation of state of dark energy strictly satisfies $w(z)= w_0+ w_a z/(1+z)$ as a function of the…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-21 David Shlivko , Paul Steinhardt

We investigate the dynamical properties of dark energy through a detailed analysis of its equation of state parameter $w(z)$ as a function of redshift. We derive a general expression for $w(z)$ from the Friedmann-Lema\^itre-Robertson-Walker…

Cosmology and Nongalactic Astrophysics · Physics 2025-05-29 J. W. Moffat , E. J. Thompson

Investigations on dark energy (DE) are currently inconclusive about its time evolution. Hints of this possibility do however glow now and then in the horizon. Herein we assess the current status of dynamical dark energy (DDE) in the light…

Cosmology and Nongalactic Astrophysics · Physics 2019-05-06 Joan Sola Peracaula , Adria Gomez-Valent , Javier de Cruz Perez

We combine complementary datasets from Cosmic Microwave Background (CMB) anisotropy measurements, high redshift supernovae (SN-Ia) observations and data from local cluster abundances and galaxy clustering (LSS) to constrain the dark energy…

Astrophysics · Physics 2009-11-07 Rachel Bean , Alessandro Melchiorri

The Planck collaboration has recently published maps of the Cosmic Microwave Background radiation with the highest precision. In the standard flat $\Lambda$CDM framework, Planck data show that the Hubble constant $H_0$ is in tension with…

Cosmology and Nongalactic Astrophysics · Physics 2013-09-04 Jun-Qing Xia , Hong Li , Xinmin Zhang

The dark energy component of the universe is often interpreted either in terms of a cosmological constant or as a scalar field. A generic feature of the scalar field models is that the equation of state parameter w= P/rho for the dark…

Astrophysics · Physics 2009-11-13 H. K. Jassal , J. S. Bagla , T. Padmanabhan

Recent results from Type Ia supernovae (SNe Ia) and baryon acoustic oscillations (BAO), in combination with cosmic microwave background (CMB) measurements, have focused renewed attention on dark energy models with a time-varying…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-31 Anowar J. Shajib , Joshua A. Frieman

We point out that the CPL parametrization has a problem that the equation of state $w(z)$ diverges in the far future, so that this model can only properly describe the past evolution but cannot depict the future evolution. To overcome such…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Jing-Zhe Ma , Xin Zhang

We study the utility of wavelets for detecting the redshift evolution of the dark energy equation of state w(z) from the combination of supernovae, CMB and BAO data. We show that local features in w, such as bumps, can be detected…

Cosmology and Nongalactic Astrophysics · Physics 2010-04-20 Alireza Hojjati , Levon Pogosian , Gong-Bo Zhao

Cosmological measurements suggest that our universe contains a dark energy component. In order to study the dark energy evolution, we constrain a parameterized dark energy equation of state $w(z)=w_0 + w_1 \frac{z}{1+z}$ using the recent…

Astrophysics · Physics 2008-11-26 Chengwu Zhang , Lixin Xu , Baorong Chang , Hongya Liu

Classification of dark energy models in the plane of w and w', where w is the dark energy equation of state and w' its time-derivative in units of the Hubble time, has been studied in the literature. We take the current SN Ia, CMB and BAO…

Cosmology and Nongalactic Astrophysics · Physics 2009-12-04 Chien-Wen Chen , Pisin Chen , Je-An Gu
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