Related papers: Dynamical Dark Energy at Late Time $\Lambda$CDM
We combine recent measurements of Cosmic Microwave Background Anisotropies, Supernovae luminosity distances and Baryonic Acoustic Oscillations to derive constraints on the dark energy equation of state w in the redshift range 0<z<2, using a…
In order to explain the current acceleration of the Universe, the fine tuning problem of the cosmological constant $\Lambda$ and the cosmic coincidence problem, different alternative models have been proposed in the literature. We use the…
The current paper provides a comprehensive examination of a dark energy cosmological model in the classical regime, in which a generic scalar field is regarded as a dark energy source. Einstein's field equations are solved in model…
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…
There is mounting evidence from multiple cosmological probes that dark energy may be dynamical, with an equation of state that evolves over cosmic time. While this evidence is typically quantified using the Chevallier-Polarski-Linder (CPL)…
We present a physically motivated dark-energy (DE) model rooted in the topological structure of the Quantum ChromoDynamic (QCD) vacuum. In this framework, DE arises from the difference between the vacuum energy of an expanding FRW universe…
We present a model--independent reconstruction of the normalized dark energy density function, $X(z) \equiv \rho_{\mathrm{de}}(z)/\rho_{\mathrm{de}}(0)$, derived directly from the DES-SN5YR Type~Ia supernova sample. The analysis employs an…
We review the ability of redshift surveys to provide constraints on the Dark Energy content of the Universe. The matter power spectrum and dynamics at the present epoch are nearly `blind' to Dark Energy, but combined with the CMB they can…
We study the evidence for dark energy (DE) evolution at low redshift, using baryonic acoustic oscillations (BAOs) from the DESI Early Data Release, Pantheon+ Type Ia supernovae (SNe-Ia), and redshift space distortions (RSDs) to constrain…
We investigate a phenomenological extension of the standard $\Lambda$CDM framework, the $\Omega_1\Omega_2$-$\Lambda$CDM model, in which the total energy density of the universe is expanded in powers of $1+z$. This parameterization recovers…
We scrutinized the Locally Rotational Symmetry (LRS) Bianchi type-I cosmological model in the presence of fractional holographic dark energy. We calculate the value of the Hubble parameter $H(z)$ using the field equations. After that, we…
We reconstruct the equation of state $w(z)$ of dark energy (DE) using a recently released data set containing 172 type Ia supernovae without assuming the prior $w(z) \geq -1$ (in contrast to previous studies). We find that dark energy…
Recent observations from the Dark Energy Spectroscopic Instrument (DESI 2025) indicate a weakening of cosmic acceleration at low redshifts $z < 1$, with effective dark energy equation of state parameters $w_0 > -1$ and $w_a < 0$. We…
We present a novel dynamical dark energy model within the frameworks of both Einstein gravity and Horava-Lifshitz gravity. Utilizing CDMMA parametrization of the dark energy equation of state $\omega(z)$, we derive solutions to the field…
We develop a simple method of dark energy reconstruction using a geometrical form of the luminosity-distance relation. In this method the FRW dynamical system with dark energy is reconstructed instead of the equation of state parameter. We…
We introduce a two-parameter phenomenological extension of the $\Lambda$CDM model in which the equation of state parameter of the ``dust'' fluid becomes different from zero for redshifts below a transition value $z_t$. Using data from DESI…
We study the integrated Sachs-Wolfe (ISW) effect using a model-independent parameterization of the dark energy equation of state. Cosmic variance severely restricts the class of models distinguishable from Lambda-CDM. In particular if the…
We propose a class of simple dark energy models which predict a late-time dark radiation component and a distinctive time-dependent equation of state $w(z)$ for redshift $z < 3$. The dark energy field can be coupled strongly enough to…
In this paper, we explore a new type of smooth and well-behaved polynomial redshift function that can avoid a future singularity. Using this function, we have proposed different redshift parametrizations of the dark energy equation of…
An important issue in cosmology is reconstructing the effective dark energy equation of state directly from observations. With so few physically motivated models, future dark energy studies cannot only be based on constraining a dark energy…