Related papers: Conformal Holographic Dark Energy
A holographic dark energy model characterized by the conformal-age-like length scale $L= \frac{1}{a^4(t)}\int_0^tdt' a^3(t') $ is motivated from the four dimensional spacetime volume at cosmic time $t$ in the flat Friedmann-Robertson-Walker…
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.…
A suitable nonlinear interaction between dark matter with an energy density $\rho_{M}$ and dark energy with an energy density $\rho_{X}$ is known to give rise to a non-canonical scaling $\rho_{M} \propto \rho_{X}a^{-\xi}$ where $\xi$ is a…
We consider an Early Dark Energy (EDE) cosmological model, and perform an analysis which takes into account both background and perturbation effects via the parameters $c^{2}_{\rm eff}$ and $c^{2}_{\rm vis}$, representing effective sound…
Cosmological consequences of adding the Cold Dark Matter (CDM) to the exactly solvable stringy Dark Energy (DE) model are investigated. The model is motivated by the consideration of our Universe as a slowly decaying D3-brane. The decay of…
As an update on the initial findings of DESI, the new results provide the first hint of potential deviations from a cosmological constant ($\omega=-1$), which, if confirmed with significance $>(2-4)\sigma$, would challenge the validity of…
In this work, we study a Dark Energy (DE) energy density model which depends on the Hubble parameter squared $H^2$ and on its first, second and third time derivatives $\dot{H}$, $\ddot{H}$ and $\dddot{H}$. Considering a scale factor $a$…
In the recent literature on dark energy (DE) model building we have learnt that cosmologies with variable cosmological parameters can mimic more traditional DE pictures exclusively based on scalar fields (e.g. quintessence and phantom). In…
Recent data from multiple supernova catalogs and DESI, when combined with CMB, suggest a non-trivial evolution of dark energy (DE) at the $2.5-4\sigma$ CL. This evidence is typically quantified using the CPL parametrization of the DE…
The interacting dark energy (IDE) model, which considers the interaction between dark energy and dark matter, provides a natural mechanism to alleviate the coincidence problem and can also relieve the observational tensions under the…
The $H_0$ tension has become one of the most significant challenges in modern cosmology. The recent DESI DR2 data has shown a significant preference for dynamical dark energy, yet this has further exacerbated the $H_0$ tension. In this…
The new Dark Energy Spectroscopic Instrument (DESI) DR2 results have strengthened the possibility that dark energy is dynamical, i.e., it has evolved over the history of the Universe. One simple, but theoretically well motivated and widely…
The phenomenological parametrizations of dark-energy (DE) equation of state can be very helpful, since they allow for the investigation of its cosmological behavior despite the fact that its underlying theory is unknown. However, although…
We present a new perturbative full-shape analysis of BOSS galaxy clustering data, including the full combination of the galaxy power spectrum and bispectrum multipoles, baryon acoustic oscillations, and cross-correlations with the…
Recent results from Type Ia Supernovae (SNe), baryon acoustic oscillations (BAO), and the cosmic microwave background (CMB) indicate 1) potentially discrepant measurements of the matter density $\Omega_m$ and Hubble constant $ H_0 $ in…
We present updated observational constraints on the simple-gDE model, characterized by a constant inertial mass density (IMD) $\rho_{\rm DE}+p_{\rm DE}$,which belongs to the broader graduated dark energy family, and compare its cosmological…
We present logistic dark energy model (LDEM), where the dark energy density follows a logistic function for the scale factor. The equation of state parameter of dark energy ($w_D$) transitioned from $-1$ in the distant past to its current…
We test the dynamical dark-energy $w_0w_a$CDM (CPL) framework against $\Lambda$CDM using CMB anisotropies and lensing together with DESI DR2, SDSS-IV, transverse/angular BAO (BAOtr), and Cepheid-calibrated PantheonPlus SN~Ia data. CPL…
Recent measurements and analyses from the Dark Energy Spectroscopic Instrument (DESI) Collaboration and supernova surveys combined with cosmic microwave background (CMB) observations, indicate that the dark energy density changes over time.…
Observations favor cosmological models with a time-varying dark energy component. But how does dynamical dark energy (DDE) influence the growth of structure in an expanding Universe? We investigate this question using high-resolution…