Related papers: Cosmological Parameters 2000
I review the current state of determinations of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance. There are two broad categories of measurements. The first…
The angular power spectrum of the cosmic microwave background (CMB) contains information on virtually all cosmological parameters of interest, including the geometry of the Universe ($\Omega$), the baryon density, the Hubble constant ($h$),…
In a recent striking discovery, Dunlop {\bf \it et al} observed a galaxy at redshift z=1.55 with an estimated age of 3.5 Gyr. This is incompatible with age estimates for a flat matter dominated universe unless the Hubble constant is less…
We have assembled a compilation of observational Hubble parameter measurements estimated with the differential evolution of cosmic chronometers, in the redshift range 0<z<1.75. This sample has been used, in combination with CMB data and…
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…
As experimentalists step up their pursuit of cold dark matter particles and neutrino masses, cosmological constraints are tightening. We compute the joint constraints on 11 cosmological parameters from cosmic microwave background and large…
In this article, we employ a machine learning (ML) approach for the estimations of four fundamental parameters, namely, the Hubble constant ($H_0$), matter ($\Omega_{0m}$), curvature ($\Omega_{0k}$) and vacuum ($\Omega_{0\Lambda}$)…
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…
The Standard Cosmological Model has experienced tremendous success at reproducing observational data by assuming a universe dominated by a cosmological constant and dark matter in a flat geometry. However, several studies, based on local…
Based on the observed increase of $\Omega _0$ as a function of cosmic scale, the Robertson--Walker metric and the Einstein equation are generalized so that $ \Omega_0$, $H_0$, and the age of the Universe, $t_0$, all become functions of…
We perform a joint likelihood analysis of the power spectra of the 2dF Galaxy Redshift Survey (2dFGRS) and the cosmic microwave background (CMB) anisotropies under the assumptions that the initial fluctuations were adiabatic, Gaussian and…
We present a study of the baryonic fraction in galaxy clusters aimed at constraining the cosmological parameters Omega_m, Omega_Lambda and the ratio between the pressure and density of the ``dark'' energy, w. We use results on the…
The Hubble parameter $H_0$, is not a univocally-defined quantity: it relates redshifts to distances in the near Universe, but is also a key parameter of the $\Lambda$CDM standard cosmological model. As such, $H_0$ affects several physical…
The anisotropy of the cosmic microwave background radiation contains information about the contents and history of the universe. We report new limits on cosmological parameters derived from the angular power spectrum measured in the first…
We have shown that the varying physical constant model is consistent with the recently published variational approach wherein Einstein equations are modified to include the variation of the speed of light c, gravitational constant G and…
The last decade has seen increasing efforts to circumscribe and bound the cosmological Hubble flow in terms of model-independent constraints on the cosmological fluid - such as, for instance, the classical energy conditions of general…
A decade ago bit-string physics predicted that the baryon/photon ratio at the time of nucleogenesis $\eta= 1/256^4$ and that the dark matter/baryonic matter ratio $\Omega_{DM}/\Omega_B= 12.7$. Accepting that the normalized Hubble constant…
We constrain the basic comological parameters using the first observations by the Very Small Array (VSA) in its extended configuration, together with existing cosmic microwave background data and other cosmological observations. We estimate…
We estimate cosmological parameters using data obtained by the Very Small Array (VSA) in its extended configuration, in conjunction with a variety of other CMB data and external priors. Within the flat $\Lambda$CDM model, we find that the…
We performed a systematic and comprehensive estimate of the Hubble constant $H_0$ via the Sunyaev-Zel'dovich temperature decrement and the X-ray measurements for clusters up to the redshift $z=0.541$, with particular attention to its…