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The evolution of a flat, isotropic and homogeneous universe is studied. The background geometry in the early phases of the universe is conjectured to be filled with causal bulk viscous cosmological fluid and dark energy. The energy density…

广义相对论与量子宇宙学 · 物理学 2012-04-23 A. Tawfik

Over the last decade, cosmological observations have attained a level of precision which allows for detailed comparison with theoretical predictions. In this paper, we briefly review some studies of the current and prospected constraints…

科普物理 · 物理学 2007-05-23 Monique Signore , Denis Puy

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…

天体物理学 · 物理学 2007-05-23 G. Steigman , T. P. Walker , A. Zentner

Inspired by the string axiverse idea, it has been suggested that the recent transition from decelerated to accelerated cosmic expansion is driven by an axion-like quintessence field with a sub-Planckian decay constant. The scenario requires…

宇宙学与河外天体物理 · 物理学 2016-07-05 Razieh Emami , Daniel Grin , Josef Pradler , Alvise Raccanelli , Marc Kamionkowski

A cosmological model is proposed for the current Universe consisted of non-interacting baryonic matter and interacting dark components. The dark energy and dark matter are coupled through their effective barotropic indexes, which are…

天体物理学 · 物理学 2009-06-15 Luis P. Chimento , Monica Forte , Gilberto M. Kremer

The CMB anisotropy depends sensitively upon the slope and amplitude of primordial density and gravitational wave fluctuations, the baryon density, the Hubble constant, the cosmological constant, the ionization history, {\it etc.} We report…

天体物理学 · 物理学 2009-09-25 J. Richard Bond , Richard L. Davis , Paul J. Steinhardt

The relic abundance of baryons - the only form of stable matter whose existence we are certain of - is a crucial parameter for many cosmological processes, as well as material evidence that there is new physics beyond the Standard Model. We…

天体物理学 · 物理学 2007-05-23 Subir Sarkar

We introduce a new method for measuring the Hubble parameter from low-redshift large-scale observations that is independent of the comoving sound horizon. The method uses the baryon-to-photon ratio determined by the primordial deuterium…

宇宙学与河外天体物理 · 物理学 2025-02-25 Alex Krolewski , Will J. Percival , Alex Woodfinden

In this review, the status of measurements of the matter density (Omega), the vaccuum energy density or cosmological constant (Lambda), the Hubble constant (H0), and ages of the oldest measured objects (t0) are summarized. Measurements of…

天体物理学 · 物理学 2009-10-30 Wendy L. Freedman

Increasing improvements in the independent determinations of the Hubble constant and the age of the universe now seem to indicate that we need a small non-vanishing cosmological constant to make the two independent observations consistent…

高能物理 - 唯象学 · 物理学 2009-10-28 Anupam Singh

We use updated Hubble parameter and baryon acoustic oscillation data, as well as other lower-redshift Type Ia supernova, Mg II reverberation-measured quasar, quasar angular size, H II starburst galaxy, and Amati-correlated gamma-ray burst…

宇宙学与河外天体物理 · 物理学 2022-05-31 Shulei Cao , Bharat Ratra

Accurate measurements of the cosmic microwave background (CMB) anisotropies with an angular resolution of a few arcminutes can be used to determine fundamental cosmological parameters such as the densities of baryons, cold and hot dark…

天体物理学 · 物理学 2016-01-13 J. Richard Bond , George Efstathiou , Max Tegmark

The cosmic microwave background temperature is a cornerstone astrophysical observable. Its present value is tightly constrained, but its redshift dependence, which can now be determined until redshift $z\sim6.34$, is also an important probe…

宇宙学与河外天体物理 · 物理学 2022-11-23 L. Gelo , C. J. A. P. Martins , N. Quevedo , A. M. M. Vieira

We constrain cosmological parameters using only Hubble parameter data and quantify the impact of future Hubble parameter measurements on parameter estimation for the most typical dark energy models. We first constrain cosmological…

宇宙学与河外天体物理 · 物理学 2018-09-27 Jia-Jia Geng , Rui-Yun Guo , Anzhong Wang , Jing-Fei Zhang , Xin Zhang

Recent cosmic microwave background (CMB) measurements over a large range of angular scales have become sensitive enough to provide interesting constraints on cosmological parameters within a restricted class of models. We use the CMB…

天体物理学 · 物理学 2008-02-03 Charles H. Lineweaver , Domingos Barbosa

Several cosmological measurements have attained significant levels of maturity and accuracy over the last decade. Continuing this trend, future observations promise measurements of the statistics of the cosmic mass distribution at an…

天体物理学 · 物理学 2008-11-26 Salman Habib , Katrin Heitmann , David Higdon , Charles Nakhleh , Brian Williams

The value of Hubble constant inferred from Planck measurements of anisotropies in the cosmic microwave background is at $4.4\sigma$ tension with direct astronomical measurements at low redshifts. Very recently, it has been conjectured that…

宇宙学与河外天体物理 · 物理学 2019-12-25 Luis A. Anchordoqui , Santiago E. Perez Bergliaffa

We set new constraints on a seven-dimensional space of cosmological parameters within the class of inflationary adiabatic models. We use the angular power spectrum of the cosmic microwave background measured over a wide range of \ell in the…

We investigate the possibility of measuring the Hubble constant, the fractional energy density components and the equation of state parameter of the ``dark energy'' using lensed multiple images of high-redshift supernovae. With future…

天体物理学 · 物理学 2009-11-07 A. Goobar , E. Mortsell , R. Amanullah , P. Nugent

An accurate determination of the Hubble constant remains a puzzle in observational cosmology. The possibility of a new physics has emerged with a significant tension between the current expansion rate of our Universe measured from the…

宇宙学与河外天体物理 · 物理学 2021-11-01 R. F. L. Holanda , G. Pordeus-da-Silva , S. H. Pereira