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Type 1a supernova magnitudes are used to fit cosmological parameters under the assumption the model will fit the observed redshift dependence. We test this assumption with the Union 2.1 compilation of 580 sources. Several independent tests…

Cosmology and Nongalactic Astrophysics · Physics 2013-11-26 Gopolang M. Mohlabeng , John P. Ralston

We are at a specific period of modern cosmology, during which the large increase of the amount of data leads to the idea that the determination of cosmological parameters has been achieved with a rather good precision. There is a large…

Astrophysics · Physics 2017-08-23 A. Blanchard

The thermodynamic and dynamical properties of a variable dark energy model with density scaling as rho_x \propto (1+z)^m, z being the redshift, are discussed following the outline of Jetzer et al. This kind of models are proven to lead to…

Cosmology and Nongalactic Astrophysics · Physics 2011-09-08 Philippe Jetzer , Crescenzo Tortora

We use the Radial Baryon Acoustic Oscillation (RBAO) measurements, distant type Ia supernovae (SNe Ia), the observational $H(z)$ data (OHD) and the Cosmic Microwave Background (CMB) shift parameter data to constrain cosmological parameters…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Zhong-Xu Zhai , Hao-Yi Wan , Tong-Jie Zhang

We propose a relativistic model of dark matter reproducing at once the concordance cosmological model $\Lambda$-Cold-Dark-Matter ($\Lambda$-CDM) at cosmological scales, and the phenomenology of the modified Newtonian dynamics (MOND) at…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Laura Bernard , Luc Blanchet

Some remarkable examples of alternative cosmological theories are reviewed here, ranging from a compilation of variations on the Standard Model through the more distant quasi-steady-state cosmology, plasma cosmology, or universe models as a…

Cosmology and Nongalactic Astrophysics · Physics 2022-08-17 Martin Lopez-Corredoira , Louis Marmet

The cosmic curvature density parameter has been constrained in the present work independent of any background cosmological model. The reconstruction is performed adopting the non-parametric Gaussian Processes (GP). The constraints on…

Cosmology and Nongalactic Astrophysics · Physics 2022-03-18 Purba Mukherjee , Narayan Banerjee

Despite the broad successes of the flat $\Lambda$CDM model and its fitness to the various cosmological observations, it confronts challenges stemming from anomalies in the measurements of the Hubble constant ($H_0$) and the amplitude of…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-28 Saeed Pourojaghi , Mohammad Malekjani

Recently, a model of modified gravity plus single scalar field model was proposed, in which the scalar couples both to the standard Riemannian volume form given by the square root of the determinant of the Riemannian metric, as well as to…

General Relativity and Quantum Cosmology · Physics 2016-12-09 Denitsa Staicova , Michail Stoilov

Data from Type Ia supernovae, along with X-ray cluster estimates of the universal baryon fraction and Big Bang Nucleosynthesis (BBN) determinations of the baryon-to-photon ratio, are used to provide estimates of several global cosmological…

Astrophysics · Physics 2007-05-23 G. Steigman , T. P. Walker , A. Zentner

In the generalized matter-geometry coupling theory, we investigate the physical characteristics and causality of some new cosmological models for a flat, homogeneous, and isotropic spacetime filled with stiff, radiation, dust, and curvature…

General Relativity and Quantum Cosmology · Physics 2025-04-10 Dinesh Chandra Maurya , Javlon Rayimbaev , Inomjon Ibragimov , Sokhibjan Muminov

Fourth - order gravity theories have received much interest in recent years thanks to their ability to provide an accelerated cosmic expansion in a matter only universe. In these theories, the Lagrangian density of the gravitational field…

Cosmology and Nongalactic Astrophysics · Physics 2009-07-28 Vincenzo F. Cardone , Antonaldo Diaferio , Stefano Camera

We investigate the observational implications of a gravitational model wherein the gravitational constant $G$ and the cosmological constant $\Lambda$ exhibit scale-dependent behavior at the perturbative level, while preserving the General…

General Relativity and Quantum Cosmology · Physics 2025-05-06 Wiliam S. Hipólito-Ricaldi , Rodrigo von Marttens , Felipe de Melo-Santos , Davi C. Rodrigues

In this manuscript, we investigate the constraints on dynamical vacuum models within the framework of $\Lambda(t)$CDM cosmology by assuming a parameterization of the vacuum energy density as $\rho_{\Lambda}(t)=\rho_{\Lambda 0} \left[1 +…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-14 Yerlan Myrzakulov , M. Koussour , M. Bulanbay , S. Muminov , J. Rayimbaev

We constrain two non-flat time-evolving dark energy cosmological models by using Hubble parameter data, Type Ia supernova apparent magnitude measurements, and baryonic acoustic oscillation peak length scale observations. The inclusion of…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-22 Omer Farooq , Data Mania , Bharat Ratra

Dark energy and the accelerated expansion of the universe have been the direct predictions of the distant supernovae Ia observations which are also supported, indirectly, by the observations of the CMB anisotropies, gravitational lensing…

Astrophysics · Physics 2008-11-26 Ram Gopal Vishwakarma

This is the third of a series of papers in which we derive simultaneous constraints on cosmological parameters and X-ray scaling relations using observations of the growth of massive, X-ray flux-selected galaxy clusters. Our data set…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 David Rapetti , Steven W. Allen , Adam Mantz , Harald Ebeling

We study the complementarity between the cosmological information obtainable with the Planck surveyour and the large scale structure (LSS) redshift surveys in LambdaCHDM cosmologies. We compute the initial full phase-space neutrino…

Astrophysics · Physics 2009-11-06 L. A. Popa , C. Burigana , N. Mandolesi

We review the observational foundations of the $\Lambda$CDM model, considered by most cosmologists as the standard model of cosmology. The Cosmological Principle, a key assumption of the model is shown to be verified with increasing…

Cosmology and Nongalactic Astrophysics · Physics 2013-04-17 Jean-Christophe Hamilton

The latest cosmological observables analyses seem to converge to a concordant view of the cosmological model: namely the power law Lambda-CDM. The recent WMAP results comfort this new standard model. Nevertheless, some degeneracy in the CMB…

Astrophysics · Physics 2007-05-23 Marian Douspis