Related papers: Is the Hubble Constant Scale-dependent?
As the 2015 results of Plancks mission have recently been made available, it is interesting to check the evolution of the scale factor and of the Hubble parameter in the light of these results. Two models in line with Einsteins field…
According to astrophysical observations value of recession velocity in a certain point is proportional to a distance to this point. The proportionality coefficient is the Hubble constant measured with 5% accuracy. It is used in many…
The enduring tension between local and distant measurements of $H_0$ remains unresolved. It was recently pointed out that cosmic microwave background (CMB) and large-scale structure (LSS) observables are invariant under a uniform rescaling…
The idea that the cosmological term, Lambda, should be a time dependent quantity in cosmology is a most natural one. It is difficult to conceive an expanding universe with a strictly constant vacuum energy density, namely one that has…
This paper introduces a statistical treatment to use Cepheid variable stars as distance indicators. The expansion rate of the Universe is also studied here through deriving the value of the Hubble constant H0. A Gaussian function…
In a series of articles, we have shown that the newly discovered plasma-redshift cosmology gives a simpler, more accurate and consistent explanation of many cosmological phenomena than the big-bang cosmology. The SNe Ia observations are in…
Multiply lensed sources experience a relative time delay in the arrival of photons. This effect can be used to measure absolute distances and the Hubble constant ($H_0$) and is known as time-delay cosmography. The methodology is independent…
It is possible to explain the discrepancy (tension) between the local measurement of the cosmological parameter $H_0$ (the Hubble constant) and its value derived from the Planck-mission measurements of the Cosmic Microwave Background (CMB)…
Bidirectional relativistic proper motions of radio components of nearby extragalactic sources give a strong constraint on the determination of the Hubble constant $H_0$. Under the assumption that the real velocity of radio components of…
The cosmological constant and many other possible origins for acceleration of the cosmic expansion possess variations in the dark energy properties slow on the Hubble time scale. Given that models with more rapid variation, or even phase…
In this work, we study the cosmological constant problem and Hubble tension in the void-dominated cosmology scenario \cite{Yusofi:2022hgg}. For this goal, we will first consider the cosmic voids in the cosmic web as interconnected ideal…
We present a simultaneous analysis of 18 galaxy lenses with time delay measurements. For each lens we derive mass maps using pixelated simultaneous modeling with shared Hubble constant. We estimate the Hubble constant to be 66_{-4}^{+6}…
Attempts to measure extragalactic distances over the last 90 years are briefly described. It follows a short history of the discovery of the expansion of space. Reasons are discussed for the decrease of the Hubble constant from Ho~500…
The discrepancy in measurements of the Hubble constant indicates new physics in dark energy, dark matter, or both. Drawing inspiration from string theory, we explore possible solutions to overcome the $H_0$ problem. We investigate the…
The hot big-bang cosmology provides a reliable accounting of the Universe from about $10^{-2}\sec$ after the bang until the present, as well as a robust framework for speculating back to times as early as $10^{-43}\sec$. Cosmology faces a…
An intriguing discrepancy emerging in the concordance model of cosmology is the tension between the locally measured value of the Hubble rate, and the 'global' value inferred from the cosmic microwave background (CMB). This could be due to…
Most of the calculations done to obtain the value of the cosmological constant use methods of quantum gravity, a theory that has not been established as yet, and a variety of results are usually obtained. The numerical value of the…
The statistical uncertainty in measuring the primordial density perturbations on a given comoving scale is dictated by the number of independent regions of that scale that are accessible to an observer. This number varies with cosmic time…
The Hubble parameter H0 still not very well measured. Although the Hubble Key Project, Chandra and WMAP gave good estimates, the uncertainties remain quite large. In this brief report, we suggest an original and independent method to derive…
The final efforts of the HST Key Project on the Extragalactic Distance Scale are presented. Four distance indicators, the Surface Brightness Fluctuation method, the Fundamental Plane for early-type galaxies, the Tully-Fisher relation and…