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I use Bousso's causal diamond measure to make a statistical prediction for the dark matter abundance, assuming an axion with a large decay constant f_a >> 10^{12} GeV. Using a crude approximation for observer formation, the prediction…

High Energy Physics - Theory · Physics 2015-05-13 Ben Freivogel

We present results from the analysis of cosmic microwave background (CMB), large scale structure (galaxy redshift survey) and X-ray galaxy cluster (baryon fraction and X-ray luminosity function) data, assuming a geometrically flat…

Astrophysics · Physics 2009-11-10 S. W. Allen , R. W. Schmidt , S. L. Bridle

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

From the observations of the anisotropies of the Cosmic Microwave Background (CMB) radiation, the WMAP satellite has provided a determination of the baryonic density of the Universe, \Omega_b.h^2, with an unprecedented precision. This…

We describe the implications of cosmic microwave background (CMB) observations and galaxy and cluster surveys of large scale structure (LSS) for theories of cosmic structure formation, especially emphasizing the recent Boomerang and Maxima…

Gravitational particle production has been investigated by using Einstein's gravitational field equations in the presence of a cosmological constant. To study the mechanism of particle creation, the Universe has been considered as a…

General Relativity and Quantum Cosmology · Physics 2020-04-07 Z. Safari , B. Malekolkalami , H. Moshafi

In this paper we compare data to theory. We use a compilation of the most recent cosmic microwave background (CMB) measurements to constrain Hubble's constant h, the baryon fraction Omega_b, and the cosmological constant lambda. We fit h-,…

Astrophysics · Physics 2008-02-03 Charles H. Lineweaver , Domingos Barbosa , Alain Blanchard , James G. Bartlett

In this paper we show that the baryon-to-photon ratio $\eta$ is in general not conserved before decoupling in non-minimally coupled theories of gravity. We use big-bang nucleosynthesis and cosmic microwave background limits on the…

General Relativity and Quantum Cosmology · Physics 2018-10-03 R. P. L. Azevedo , P. P. Avelino

Spacetime variations of physical constants can be associated with the existence of Higgs-like scalar field(s) that couple non-universally to the baryonic matter. Recent results of astronomical spectral measurements of the fractional changes…

Cosmology and Nongalactic Astrophysics · Physics 2021-02-03 S. A. Levshakov

We present a determination of the Hubble constant from the joint, free-form analysis of 8 strongly, quadruply lensing systems. In the concordance cosmology, we find $H_0 = 71.8^{+3.9}_{-3.3}\,\mathrm{km}\,\mathrm{s}^{-1}\,\mathrm{Mpc}^{-1}$…

Cosmology and Nongalactic Astrophysics · Physics 2021-02-22 Philipp Denzel , Jonathan P. Coles , Prasenjit Saha , Liliya L. R. Williams

In this work a satisfactory, simple theoretical prediction of the data corresponding to observationally (by fine tuning condition) estimated value of the cosmological constant is given. It is supposed (in conceptually analogy with…

Astrophysics · Physics 2007-12-27 Vladan Pankovic , Simo Ciganovic , Jovan Ivanovic , Rade Glavatovic , Petar Grujic

To elucidate the significance of the effect of systematic uncertainties in light element abundance estimates on cosmological bounds derivable from Big Bang Nucleosynthesis (BBN) we present tables giving bounds on $\Omega_{baryon}$ and…

Astrophysics · Physics 2009-10-22 Lawrence M. Krauss , Peter J. Kernan

The Hubble constant $H_{0}$ and matter density $\Omega_{m}$ of the Universe are measured using the latest $\gamma$-ray attenuation results from Fermi-LAT and Cherenkov telescopes. This methodology is based upon the fact that the…

In axion quintessence, the cosmological era with an energy contrast in dark energy 0.1 < Omega_DE < 0.9 may represent a significant fraction of the universe's lifetime if the minimum of the axion potential is negative (unstable axion…

Cosmology and Nongalactic Astrophysics · Physics 2012-09-07 Carl L. Gardner

Based on the assumption that some apparent properties of the observable universe are accurate at a reasonable level of approximation, a tentative is made to independently derive the values of the baryon density parameter, the Hubble…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 A. Dinculescu

In the standard Big Bang cosmology the canonical value for the ratio of relic neutrinos to CMB photons is 9/11. Within the framework of the Standard Model of particle physics there are small corrections, in sum about 1%, due to slight…

Astrophysics · Physics 2009-10-30 Robert E. Lopez , Scott Dodelson , Andrew Heckler , Michael S. Turner

We estimate the cosmological variation of the proton-to-electron mass ratio \mu=m_p/m_e by measuring the wavelengths of molecular hydrogen transitions in the early universe. The analysis is performed using high spectral resolution…

Astrophysics · Physics 2009-11-07 A. Ivanchik , E. Rodriguez , P. Petitjean , D. Varshalovich

The \HOmega\ diagram is resurrected to dramatically illustrate the nature of the key problems in physical cosmology today and the role that nuclear physics plays in many of them. In particular it is noted that the constraints on \OmegaB\…

Astrophysics · Physics 2014-10-13 Craig J. Copi , David N. Schramm

The details of the CMB power spectrum are being revealed through the combined efforts of the world's CMBologists. The current data set constrains several cosmological parameters. A combination with other (non-lensing) constraints yields…

Astrophysics · Physics 2007-05-23 Charles H. Lineweaver

The recent local measurements of the Hubble constant $H_0$, indicate a significant discrepancy of over 5$\sigma$ compared to the value inferred from \textit{Planck} observations of the cosmic microwave background (CMB). In this paper, we…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-24 Guanlin Liu , Yu Wang , Wen Zhao