Related papers: Bounding the Hubble flow in terms of the w paramet…
We present a comprehensive study of the observational constraints on spatially flat cosmological models containing a mixture of matter and quintessence --- a time varying, spatially inhomogeneous component of the energy density of the…
We use the Simon, Verde, & Jimenez (2005) determination of the redshift dependence of the Hubble parameter to constrain cosmological parameters in three dark energy cosmological models. We consider the standard $\Lambda$CDM model, the XCDM…
Classification of dark energy models in the plane of w and w', where w is the dark energy equation of state and w' its time-derivative in units of the Hubble time, has been studied in the literature. We take the current SN Ia, CMB and BAO…
Recently funded satellites will map the cosmic microwave background radiation with unprecedented sensitivities and angular resolutions. Assuming only primordial adiabatic scalar and tensor perturbations, we evaluate how accurately…
The Hubble constant, which measures the expansion rate, together with the total energy density of the Universe, sets the size of the observable Universe, its age, and its radius of curvature. Excellent progress has been made recently toward…
Microlensing observations can be used for determining the shape of the Milky Way's halo. It can be shown that the data are best described with moderately flattened halo, 0.5 < q < 0.6. We discuss, by taking into account this result, the…
Are geometrical summaries of the CMB and LSS sufficient for estimating cosmological parameters? And how does our choice of a dark energy model impact the current constraints on standard cosmological parameters? We address these questions in…
In this work, we have considered the flat FRW model of the universe in $(n+2)$-dimensions filled with the dark matter (perfect fluid with negligible pressure) and the modified Chaplygin gas (MCG) type dark energy. We present the Hubble…
A discrete class of privileged reference frames in a closed universe with identical equations of motion for physical degrees of freedom was found. A representation of the quantum state of the universe in a privileged reference frame was…
This paper is a review on the observational Hubble parameter data that have gained increasing attention in recent years for their illuminating power on the dark side of the universe --- the dark matter, dark energy, and the dark age.…
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…
Based on the latest MLCS17 SNe Ia data provided by Hicken et al. (2009), together with the Baryon Acoustic Oscillation (BAO) and strong gravitational lenses (SGL), we investigate the dark energy equation-of-state parameter for both constant…
We consider the cosmology that results if our observable universe is a 3-brane in a higher dimensional universe. In particular, we focus on the case where our 3-brane is located at the $Z_2$ symmetry fixed plane of a $Z_2$ symmetric…
In this paper we present cosmological constraints on several well-known $f(R)$ models, but also on a new class of models that are variants of the Hu-Sawicki one of the form $f(R)=R-\frac{2\Lambda}{1+b\;y(R,\Lambda)}$, that interpolate…
We study a generalized holographic dark energy model in which the infrared cutoff depends on the Hubble parameter and its first two time derivatives. The inclusion of the $\ddot H$ term introduces a finite relaxation timescale for the…
The first section discusses a recalibration of the luminosity-linewidth technique and its use in a determination of H_0. The recalibration introduces (i) new cluster calibration data, (ii) new corrections for reddening as a function of…
We use a generalised procedure for the combined likelihood analysis of different cosmological probes, the `Hyper-Parameters' method, that allows freedom in the relative weights of the raw measurements. We perform a joint analysis of the…
Thermodynamics on the horizon of a flat universe at late times is studied in holographic cosmological models that assume an associated entropy on the horizon. In such models, a $\Lambda(t)$ model similar to a time-varying $\Lambda(t)$…
Cosmological constraints are usually derived under the assumption of a $6$ parameters $\Lambda$-CDM theoretical framework or simple one-parameter extensions. In this paper we present, for the first time, cosmological constraints in a…
We compile a list of 28 independent measurements of the Hubble parameter between redshifts 0.07 < z < 2.3 and use this to place constraints on model parameters of constant and time-evolving dark energy cosmologies. These H(z) measurements…