Related papers: Has DESI detected exponential quintessence?
Understanding whether cosmic acceleration arises from a cosmological constant or a dynamical component is a central goal of cosmology, and the Dark Energy Spectroscopic Instrument (DESI) enables stringent tests with high-precision distance…
We present strong evidence for dynamical dark energy that challenges the standard $\Lambda$CDM model. Several dark energy scenarios are explored, including $\omega_0\omega_a$CDM, logarithmic, exponential, JBP, and BA parameterizations,…
New constraints on the expansion rate of the Universe seem to favor evolving dark energy in the form of thawing quintessence models, i.e., models for which a canonical, minimally coupled scalar field has, at late times, begun to evolve away…
We continue scientific scrutiny of the DESI dynamical dark energy (DE) claim by explicitly demonstrating that the result depends on the analysis pipeline. Concretely, we define a likelihood that converts the $w_0 w_a$CDM model back into the…
Recently, a $3\sim4\sigma$ preference for dynamical dark energy has been reported by the Dark Energy Spectroscopic Instrument (DESI) collaboration, which has inspired hot debates on new physics or systematics. In this paper, we reveal that…
Baryon acoustic oscillation data from the Dark Energy Spectroscopic Instrument (DESI) show evidence of a deviation from a cosmological constant $\Lambda$ within a Bayesian analysis. In this work, we validate that frequentist constraints…
Neutrinos and dark energy (DE) have entered a new era of investigation, as the latest DESI baryon acoustic oscillation measurements tighten the constraints on the neutrino mass and suggest that DE may be dynamical rather than a cosmological…
Recently we proposed a new approach to the testing of dark energy models based on the observational data. In that work we focused particularly on quintessence models for demonstration and invoked a widely used parametrization of the dark…
We propose a dark energy model in which a quintessence field $\phi$ rolls near the vicinity of a local maximum of its potential characterized by the simplest $S$ self-dual form $V(\phi) = \Lambda \ {\rm sech}(\sqrt{2} \, \phi/M_p)$, where…
We review late-time cosmic acceleration after DESI Data Release 2 (DR2), emphasizing the interplay between Type Ia supernovae (SNe Ia), anisotropic BAO, CMB calibration, and perturbation-sensitive probes (RSD and weak lensing). DESI DR2…
We investigate a dark energy (DE) equation of state (EoS) parametrization in a curved spacetime using current observations. We constrain the model parameters by using observational Hubble data from Cosmic Chronometer (CC), Pantheon Plus…
DESI has reported a dynamical dark energy (DE) signal based on the $w_0 w_a$CDM model that is in conflict with Hubble tension. Recalling that the combination of DESI DR1 BAO and DR1 full-shape (FS) modeling are consistent with $\Lambda$CDM,…
The main aim of this work is to use a model-independent approach, along with late-time observational probes, to reconstruct the dark energy (DE) equation of state $w_{\rm DE}(z)$. Our analysis showed that, for a late time universe, $w_{\rm…
A flat Friedman-Roberson-Walker universe dominated by a cosmological constant ($\Lambda$) and cold dark matter (CDM) has been the working model preferred by cosmologists since the discovery of cosmic acceleration. However, tensions of…
We introduce a minimal two-parameter formulation of the dark energy (DE) density evolution normalized to its present-day value, $f_{\rm DE}(z) \equiv \rho_{\rm DE}(z)/\rho_{\rm DE,0}$, in terms of $f_p\equiv f_{\rm DE}(z_p)$ and the DE…
By assuming a phenomenological form for the ratio of the DE and DM densities $\rho_X\propto \rho_{m} a^{\xi}$ (Dalal et al.2001), we discuss the cosmic coincidence problem in light of current observational data. $\xi$ is a key parameter to…
Motivated by the recent Dark Energy Spectroscopic Instrument (DESI) DR2 preference for dynamical dark energy, we study interacting dark energy models in which a canonical quintessence field couples to cold dark matter through a…
Recent cosmological observations, including the latest Dark Energy Spectroscopic Instrument (DESI) data releases DR1 and DR2, have renewed interest in the possibility that dark energy may exhibit dynamical behavior rather than being a…
A cosmological model with an energy transfer between dark matter (DM) and dark energy (DE) can give rise to comparable energy densities at the present epoch. The present work deals with the perturbation analysis, parameter estimation and…
Many ambitious experiments have been proposed to constrain dark energy and detect its evolution. At present, observational constraints are consistent with a cosmological constant and there is no firm evidence for any evolution in the dark…