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We have reanalysed constraints on the equation of state parameter, w_Q = P/rho, of the dark energy, using several cosmological data sets and relaxing the usual constraint w_Q > -1. We find that combining Cosmic Microwave Background, large…

Astrophysics · Physics 2009-11-07 Steen Hannestad , Edvard Mortsell

We explore and compare the capabilities of the recent observations of standard cosmological probes and the future observations of gravitational-wave (GW) standard sirens on constraining cosmological parameters. It is carried out in the…

Cosmology and Nongalactic Astrophysics · Physics 2022-06-22 Jie Zheng , Yun Chen , Tengpeng Xu , Zong-Hong Zhu

The Universe's initial conditions, in particular baryon and cold dark matter (CDM) isocurvature perturbations, are poorly constrained on sub-Mpc scales. In this paper, we develop a new formalism to compute the effect of small-scale baryon…

Cosmology and Nongalactic Astrophysics · Physics 2021-11-24 Nanoom Lee , Yacine Ali-Haïmoud

The cosmological principle is a cornerstone of the standard cosmological model. However, recent observations suggest potential deviations from this assumption, hinting at a small anisotropic expansion. Such an expansion can arise from…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-23 Jose L. Palacios-Córdoba , J. Bayron Orjuela-Quintana , Gabriela A. Valencia-Zuñiga , César A. Valenzuela-Toledo

We extend the previously described CMB Gibbs sampling framework to allow for exact Bayesian analysis of anisotropic universe models, and apply this method to the 5-year WMAP temperature observations. This involves adding support for…

Astrophysics · Physics 2011-02-11 Nicolaas E. Groeneboom , Hans Kristian Eriksen

We study some cosmological constraints on the two phenomenological models of oscillating dark energy. In these scenarios, the equation of state of dark energy varies periodically and may provide a way to unify the early acceleration…

Astrophysics · Physics 2009-06-23 Deepak Jain , Abha Dev , J. S. Alcaniz

The recent results on the baryon acoustic oscillations measurements from the DESI collaboration have shown tantalizing hints for a time-evolving dark energy equation of state parameter $w(z)$, with a statistically significant deviation from…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-14 George Alestas , Marienza Caldarola , Sachiko Kuroyanagi , Savvas Nesseris

The $f(R)$ modified gravity theory can explain the accelerating expansion of the late Universe without introducing dark energy. In this study, we predict the constraint strength on the $f(R)$ theory using the mock data generated from the…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-15 Jun-Hui Yan , Yan Gong , Minglin Wang , Haitao Miao , Xuelei Chen

We present constraints on cosmological and star formation parameters based on combining observations of the Wilkinson Microwave Anisotropy Probe (WMAP) and high-redshift quasars from the Sloan Digital Sky Survey (SDSS). We use a…

Astrophysics · Physics 2009-11-07 Weihsueh A. Chiu , Xiaohui Fan , Jeremiah P. Ostriker

The CMB data recently released by BOOMERANG and MAXIMA suggest that the anisotropy spectrum has a third peak in the range 800<l_3<900. A combination of this result with constraints from large-scale structure permit us to differentiate…

Astrophysics · Physics 2009-11-06 Michael Doran , Matthew Lilley , Christof Wetterich

We present constraints on the abundance of carbon-monoxide in the early Universe from the CO Power Spectrum Survey (COPSS). We utilize a data set collected between 2005 and 2008 using the Sunyaev-Zel'dovich Array (SZA), which were…

The study of cosmic expansion history and the late time cosmic acceleration from observational data depends on the nuisance parameters associated with the data. For example, the absolute peak magnitude of type Ia supernova associated with…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-19 Bikash R. Dinda

We use observational data from Type Ia Supernovae (SN), Baryon Acoustic Oscillations (BAO), Cosmic Microwave Background (CMB) and observational Hubble data (OHD), and the Markov Chain Monte Carlo (MCMC) method, to constrain the cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-13 Jianbo Lu , Emmanuel N. Saridakis , M. R. Setare , Lixin Xu

We constrain and compare the $w_{0}w_{a}$CDM dynamical dark energy model and three $f(R)$ modified gravity models using the current cosmological distance measurements, including 112 high-quality localized FRBs, BAO measurements from the…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-24 Shuai Feng , Yan Gong , Xiaohui Liu , Jun-Hui Yan , Xuelei Chen

The extended Galileon models possess tracker solutions with de Sitter attractors along which the dark energy equation of state is constant during the matter-dominated epoch, i.e. w_DE = -1-s, where s is a positive constant. Even with this…

Cosmology and Nongalactic Astrophysics · Physics 2012-03-19 Antonio De Felice , Shinji Tsujikawa

We use lookback time versus redshift data from galaxy clusters (Capozziello et al., 2004) and passively evolving galaxies (Simon et al., 2005), and apply a bayesian prior on the total age of the Universe based on WMAP measurements, to…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Lado Samushia , Abha Dev , Deepak Jain , Bharat Ratra

Two new one-parameter tracking behavior dark energy representations $\omega=\omega_0/(1+z)$ and $\omega=\omega_0 e^{z/(1+z)}/(1+z)$ are used to probe the geometry of the Universe and the property of dark energy. The combined type Ia…

Astrophysics · Physics 2009-11-10 Yungui Gong , Yuan-Zhong Zhang

There is a persistent $H_0$-tension, now at more than $\gtrsim 4\sigma$ level, between the local distance ladder value and the \emph{Planck} cosmic microwave background measurement, in the context of flat $\Lambda$CDM model. We reconstruct…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-30 Meng-Zhen Lyu , Balakrishna S. Haridasu , Matteo Viel , Jun-Qing Xia

In this paper, we study the cosmological implications of the 100 square degree Weak Lensing survey (the CFHTLS-Wide, RCS, VIRMOS-DESCART and GaBoDS surveys). We combine these weak lensing data with the cosmic microwave background (CMB)…

Astrophysics · Physics 2010-05-07 Hong Li , Jie Liu , Jun-Qing Xia , Lei Sun , Zu-Hui Fan , Charling Tao , Andre Tilquin , Xinmin Zhang

Combining cosmological probes has consolidated the standard cosmological model with percent precision, but some tensions have recently emerged when certain parameters are estimated from the local or primordial Universe. The origin of this…

Cosmology and Nongalactic Astrophysics · Physics 2023-11-16 Fabrizio Cogato , Michele Moresco , Lorenzo Amati , Andrea Cimatti