Related papers: Reconciling a decelerating Universe with cosmologi…
Scalar-tensor theories of gravity provide a consistent framework to accommodate an ultra-light quintessence scalar field. While the equivalence principle is respected by construction, deviations from General Relativity and standard…
Is the accelerating expansion of the Universe true, inferred through observations of distant supernovae, and is the implied existence of an enormous amount of anti-gravitational dark energy material driving the accelerating expansion of the…
We extend the results of a previous paper where a model of interacting dark energy, with a cosmological term decaying linearly with the Hubble parameter, is tested against the observed mass power spectrum. In spite of the agreement with…
Observations of supernovae of type Ia require dark energy (some unknown exotic \emph{`matter'} of negative pressure) to explain their unexpected faintness. Whereas the simplest and most favoured candidate of dark energy, the Einsteinian…
Cosmic acceleration is explained quantitatively, as an apparent effect due to gravitational energy differences that arise in the decoupling of bound systems from the global expansion of the universe. "Dark energy" is a misidentification of…
Current observations do not rule out the possibility that the Universe might end up in an abrupt event. Different such scenarios may be explored through suitable parameterizations of the dark energy and then confronted to cosmological…
Cosmological observations are normally fit under the assumption that the dark sector can be decomposed into dark matter and dark energy components. However, as long as the probes remain purely gravitational, there is no unique decomposition…
Cosmological backreaction has been suggested as an explanation of dark energy and is heavily disputed since. We combine cosmological perturbation theory with Buchert's non-perturbative framework, calculate the relevant averaged observables…
Faced by recent evidence for a flat universe dominated by dark energy, cosmologists grapple with deep cosmic enigmas such as the cosmological constant problem, extreme fine-tuning and the cosmic coincidence problem. The extent to which we…
The two dark sectors of the universe - dark matter and dark energy - may interact with each other. Background and linear density perturbation evolution equations are developed for a generic coupling. We then establish the general conditions…
A novel idea is proposed for a natural solution of the dark energy and its cosmic coincidence problem. The existence of local antigravity sources, associated with astrophysical matter configurations distributed throughout the universe, can…
This paper is based on two insights: (1) that general relativity alone does not specify how much of the matter density contributes to the source term in Friedmann's equation, and how much contributes as the source of the gravitational…
We show that the latest empirical constraints on cosmology, from a combination of DESI, CMB and supernova data, can be accounted for if a small component of dark matter has an evolving and oscillating equation of state within $-1<w<1$. From…
In this paper a new theory of Dark Matter is proposed. Experimental analysis of several Galaxies show how the non-gravitational contribution to galactic Velocity Rotation Curves can be interpreted as that due to the Cosmological Constant…
The consideration of dark energy's quanta, required also by thermodynamics, introduces its chemical potential into the cosmological equations. Isolating its main contribution, we obtain solutions with dark energy decaying to matter or…
Discoveries in the last few years have revolutionized our knowledge of the universe and our ideas of its ultimate fate. Measurements of the expansion of the universe show that it is not slowing down under normal gravity but accelerating due…
We outline a dynamical dark energy scenario whose signatures may be simultaneously tested by astronomical observations and laboratory experiments. The dark energy is a field with slightly sub-gravitational couplings to matter, a logarithmic…
Despite the observational success of the standard model of cosmology, present-day observations do not tightly constrain the nature of dark matter and dark energy and modifications to the theory of general relativity. Here, we will discuss…
Till the late nineties the accepted cosmological model was that of a Universe that had originated in the Big Bang and was now decelerating under the influence of as yet undetected dark matter, so that it would come to a halt and eventually…
New observational constraints on the cosmic matter density $\Omega_m$ and an effectively redshift-independent equation of state parameter $w_x$ of the dark energy are obtained while simultaneously testing the strong and null energy…