Related papers: Dynamical dark energy versus $\Lambda=$const. in l…
A huge amount of good quality data converges towards the picture of a spatially flat universe undergoing the today observed phase of accelerated expansion. This new observational trend is commonly addressed as Precision Cosmology. Despite…
Recent baryon acoustic oscillation (BAO) measurements released by DESI, when combined with cosmic microwave background (CMB) data and type Ia supernova (SN) data, suggest a significant preference for dynamical dark energy (DDE) that…
The first and second year results of DESI provide consistent evidence that dark energy may not be quantum vacuum energy ($\Lambda$). If true, this would be an extraordinary development in the 25-year quest to understand cosmic acceleration.…
We present a comprehensive analysis of the $\Lambda_{\rm s}$CDM model, which explores the recent conjecture suggesting a rapid transition of the Universe from anti-de Sitter vacua to de Sitter vacua (viz., the cosmological constant switches…
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…
In this work, we consider the possibility that the dynamical dark energy hinted at by recent DESI data may be mimicked by the effects of additional components in the universe, potentially arising from topological defects. We find that the…
We investigate the impact of a DESI motivated dynamic dark energy cosmology on three cosmological anomalies, the $S_8$ tension, the `lensing is low' effect, and observations of strong baryonic feedback. We analyze how these observations…
This is a review and statistical analysis of the evidence supporting the existence of a cosmological constant in the early 1990s, before its discovery made with distant supernovae in 1998. The earlier evidence was derived from newly precise…
Combined cosmological probes currently indicate that best-fit values in the $w_0-w_a$ parametrization of dynamical dark energy deviate from $\Lambda$CDM by $\sim3\sigma$. In this work, we present a supernova survey capable of measuring…
Recently, the DESI BAO data has reported a preference of dynamical dark energy (DDE) over the \LambdaCDM cosmology. Apart from the BAO data, the DDE model should be also sensitive to low-redshift measurements of the matter power spectrum…
Is Dark Energy justified as an alternative to the cosmological constant $\Lambda$ in order to explain the acceleration of the cosmic expansion ? It turns out that a straightforward dimensional analysis of Einstein equation provides us with…
In order to explain the Late-times accelerated expansion of the Universe we must appeal to some form of Dark Energy. In the standard model of cosmology, the latter is interpreted as a Cosmological Constant $\Lambda$. However, for a number…
The early dark energy (EDE) extension to $\Lambda$CDM has been proposed as a candidate scenario to resolve the "Hubble tension". We present new constraints on the EDE model by incorporating new data from the Dark Energy Spectroscopic…
Recently, Dark Energy Spectroscopic Instrument (DESI) collaboration based on their first year data has reported a $\gtrsim 3\sigma$ evidence for an evolving dark energy (DE) against the cosmological constant (CC), so the standard…
We discuss the evolution of density perturbations of dark matter and dark energy in cosmological models which admit future singularities in a finite time. Up to now geometrical tests of the evolution of the universe do not differentiate…
While $f(T)$ gravity has shown considerable potential in addressing cosmological tensions, we explore previously overlooked solution spaces that hold further promise. We examine the case where the customary assumption of a strictly positive…
In this paper we review in detail a number of approaches that have been adopted to try and explain the remarkable observation of our accelerating Universe. In particular we discuss the arguments for and recent progress made towards…
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…
We compute the Bayesian evidences for one- and two-parameter models of evolving dark energy, and compare them to the evidence for a cosmological constant, using current data from Type Ia supernova, baryon acoustic oscillations, and the…
Observational evidence indicating that the expansion of the universe is accelerating has surprised cosmologists in recent years. Cosmological models have sought to explain this acceleration by incorporating `dark energy', of which the…