Related papers: Dark Energy and the Hubble Constant
Phenomena currently attributed to Dark Matter (DM) and Dark Energy (DE) are merely a result of the interplay between gravitational energy density, caused by the contraction of space by matter, and space dilation, caused by the energy…
Early dark energy, as a proposed solution to the Hubble tension, faces an additional "why now" problem. Why should dark energy emerge just prior to recombination, billions of years before the onset of cosmic acceleration? Assisted…
It has recently been shown that the observed Hubble function for cosmological expansion can be fitted accurately back to redshift unity (7.33 Gyr ago) with only one free constant, while neglecting cosmic curvature and mass, using the…
The acceleration of the expansion of the universe, ascribed to a dark energy, is one of the most intriguing discoveries in science. In addition to precise, systematics controlled data, clear, robust interpretation of the observations is…
Assuming that the Universe at higher redshifts (z \sim 4 and beyond) is consistent with LCDM model as constrained by the Planck measurements, we reanalyze the low redshift cosmological data to reconstruct the Hubble parameter as a function…
The traditional "explanation" for the observed acceleration of the universe is the existence of a positive cosmological constant. However, this can hardly be a truly convincing explanation, as an expanding universe is not expected to have a…
The accelerating expansion of the universe is the most surprising cosmological discovery in many decades. In this short review, we briefly summarize theories for the origin of cosmic acceleration and the observational methods being used to…
We show that current cosmic acceleration can be explained by an almost massless scalar field experiencing quantum fluctuations during primordial inflation. Provided its mass does not exceed the Hubble parameter today, this field has been…
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…
The effect of "dark energy" (i.e. the Lambda-term in Einstein equations) is sought for at the interplanetary scales by comparing the rates of secular increase in the lunar orbit obtained by two different ways: (1) measured immediately by…
Despite the many efforts, our theoretical understanding of the ultimate nature of the dark energy component of the universe still lags well behind the astounding experimental evidence achieved from the increasingly sophisticated…
A mildly inhomogeneous universe with a cosmological constant may look like it contains evolving dark energy. We show that could be the case by modelling the inhomogeneities and their effects in three different ways: as clumped matter…
The Hubble relation between distance and redshift is a purely cosmographic relation that depends only on the symmetries of a FLRW spacetime, but does not intrinsically make any dynamical assumptions. This suggests that it should be possible…
The presence of dark energy in the Universe is inferred directly from the accelerated expansion of the Universe, and indirectly, from measurements of cosmic microwave background (CMB) anisotropy. Dark energy contributes about 2/3 of the…
Dark energy affects the Hubble expansion rate (namely, the expansion history) $H(z)$ by an integral over $w(z)$. However, the usual observables are the luminosity distances or the angular diameter distances, which measure the…
Recent measurements of the parameters of the Concordance Cosmology Model ($\Lambda$CDM) done in the low-redshift Universe with Supernovae Ia/Cepheids, and in the distant Universe done with Cosmic Microwave Background (CMB) imply different…
The cosmological constant, which was introduced by Einstein a century ago to allow for a static universe, experienced a revival two decades ago under the label dark energy as a parameter to model the observed accelerated expansion of the…
Physics invites the idea that space contains energy whose gravitational effect approximates that of Einstein's cosmological constant, Lambda; nowadays the concept is termed dark energy or quintessence. Physics also suggests the dark energy…
We study how the determination of the Hubble constant from cosmological distance measures is affected by models of dark energy and vice versa. For this purpose, constraints on the Hubble constant and dark energy are investigated using the…
Several independent cosmological data, collected within the last twenty years, revealed the accelerated expansion rate of the Universe, usually assumed to be driven by the so called dark energy, which, according to recent estimates,…