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Gravitational wave signals from coalescing Massive Black Hole (MBH) binaries could be used as standard sirens to measure cosmological parameters. The future space based gravitational wave observatory Laser Interferometer Space Antenna…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-18 Antoine Petiteau , Stanislav Babak , Alberto Sesana

We use all available baryon acoustic oscillation distance measurements and Hubble parameter data to constrain the cosmological constant $\Lambda$, dynamical dark energy, and spatial curvature in simple cosmological models. We find that the…

Cosmology and Nongalactic Astrophysics · Physics 2018-07-19 Joseph Ryan , Sanket Doshi , Bharat Ratra

The interacting dark energy model could propose a effective way to avoid the coincidence problem. In this paper, dark energy is taken as a fluid with a constant equation of state parameter $w_x$. In a general gauge, we could obtain two sets…

Cosmology and Nongalactic Astrophysics · Physics 2014-04-10 Weiqiang Yang , Lixin Xu

In a previous work it was shown that by considering the quantum nature of the gravitational field mediator, it is possible to introduce the momentum energy of the graviton into the Einstein equations as an effective cosmological constant.…

General Physics · Physics 2022-03-16 Tonatiuh Matos , Luis Osvaldo Tellez-Tovar

We present constraints on the mean matter density, Omega_m, the normalization of the density fluctuation power spectrum, sigma_8, and the dark-energy equation-of-state parameter, w, obtained from measurements of the X-ray luminosity…

Astrophysics · Physics 2010-02-03 A. Mantz , S. W. Allen , H. Ebeling , D. Rapetti

A holographic dark energy model characterized by the conformal-age-like length scale $L= \frac{1}{a^4(t)}\int_0^tdt' a^3(t') $ is motivated from the four dimensional spacetime volume at cosmic time $t$ in the flat Friedmann-Robertson-Walker…

High Energy Physics - Theory · Physics 2015-06-04 Zhuo-Peng Huang , Yue-Liang Wu

We investigate a dark energy (DE) equation of state (EoS) parametrization in a curved spacetime using current observations. We constrain the model parameters by using observational Hubble data from Cosmic Chronometer (CC), Pantheon Plus…

General Physics · Physics 2026-05-13 D. Revanth Kumar , Santosh Kumar Yadav

An overview is presented of a recently proposed "radically conservative" solution to the problem of dark energy in cosmology. The proposal yields a model universe which appears to be quantitatively viable, in terms of its fit to supernovae…

Astrophysics · Physics 2017-08-23 David L. Wiltshire

The equation of state parameter is a significant method for characterizing dark energy models. We investigate the evolution of the equation of state parameter with redshift using a Bayesian analysis of recent observational datasets (the…

General Relativity and Quantum Cosmology · Physics 2023-02-15 Gaurav N. Gadbail , Simran Arora , P. K. Sahoo

Early dark energy models, for which the contribution to the dark energy density at high redshifts is not negligible, influence the growth of cosmic structures and could leave observable signatures that are different from the standard…

Cosmology and Nongalactic Astrophysics · Physics 2009-04-01 Jun-Qing Xia , Matteo Viel

There is mounting evidence from multiple cosmological probes that dark energy may be dynamical, with an equation of state that evolves over cosmic time. While this evidence is typically quantified using the Chevallier-Polarski-Linder (CPL)…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-02 Daniel A. Kessler , Luis A. Escamilla , Supriya Pan , Eleonora Di Valentino

We put forward a new model-independent reconstruction scheme for dark energy which utilises the expected geometrical features of the luminosity-distance relation. The important advantage of this scheme is that it does not assume explicit…

Astrophysics · Physics 2008-11-26 Stephane Fay , Reza Tavakol

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

In this work, we assume the FRLW Universe which is filled with dark matter along with dark energy in the framework of Horava-Lifshitz (HL) gravity. The dark energy is considered as the Linear (Model I) and CPL (Model II) parametrizations of…

General Relativity and Quantum Cosmology · Physics 2024-02-07 Himanshu Chaudhary , Niyaz Uddin Molla , Madhur Khurana , Ujjal Debnath , G. Mustafa

An analysis of cosmological mixed dark matter models in spatially flat Friedmann Universe with zero $\Lambda$-term is presented. We argue that the introduction of cosmic gravity waves helps to satisfy observational constraints. The analysis…

Astrophysics · Physics 2007-05-23 E. V. Mikheeva

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

The ages of two old galaxies (53W091, 53W069) at high redshifts are used to constrain the value of the cosmological constant in a flat universe ($\Lambda$CDM) and the density parameter $\Omega_M$ in Friedmann-Robertson-Walker (FRW) models…

Astrophysics · Physics 2009-10-31 J. S. Alcaniz , J. A. S. Lima

We use the Gurvits, Kellermann, & Frey compact radio source angular size versus redshift data to place constraints on cosmological model parameters in models with and without a constant or time-variable cosmological constant. The resulting…

Astrophysics · Physics 2009-11-07 Gang Chen , Bharat Ratra

The recent observations support that our universe is flat and expanding with acceleration. A quintessence model with a general relation between the quintessence potential and the quintessence kinetic energy was proposed to explain the…

Astrophysics · Physics 2009-11-10 Yungui Gong

By combining data from seven cosmic microwave background experiments (including the latest WMAP results) with large scale structure data, the Hubble parameter measurement from the Hubble Space Telescope and luminosity measurements of Type…

Astrophysics · Physics 2008-11-26 Alessandro Melchiorri , Laura Mersini , Carolina J. Odman , Mark Trodden