Related papers: Notes on Ghost Dark Energy
We reconstruct evolution of the dark energy (DE) density using a nonparametric Bayesian approach from a combination of latest observational data. We caution against parameterizing DE in terms of its equation of state as it can be singular…
We reconsider the holographic dark energy (HDE) model with a slowly time varying $ c^2(z)$ parameter in the energy density, namely $\rho_D=3M_p^2 c^2(z)/L^2$, where $L$ is the IR cutoff and $z$ is the redshift parameter. As the system's IR…
It is found that the evolutions of density perturbations on the super-Hubble scales are unstable in the model with dark-sector interaction $Q$ proportional to the energy density of cold dark matter (CDM) $\rho_m$ and constant equation of…
This paper focuses on developing a generalized ghost dark energy model $f\mathcal{(Q,T)}$ through the correspondence scheme for a non-interacting scenario involving pressureless matter and a power-law scale factor. We analyze the…
After about two decades of the first observational papers confirming the accelerated expansion of the universe, we are still facing the question whether the cause of it is a rigid cosmological constant $\Lambda$-term or a mildly evolving…
Despite the great progress of current cosmological measurements, the nature of the dominant component of the universe, coined dark energy, is still an open question. Early Dark Energy is a possible candidate which may also alleviate some…
We present a model in which the Gauss-Bonnet invariant holds the quintessence at a fixed point, respecting an initial $Z_2$ symmetry in the radiation-dominated era. This results in an early dark energy that becomes significant around the…
We investigate a unified dark-energy scenario based on the combined effects of Barrow entropy corrections and the QCD ghost mechanism, referred to as the BH--QCDGDE model. The dark-energy density is constructed in a generalized holographic…
The cosmological model with an interaction between dynamical quintessence dark energy and cold dark matter is considered. Evolution of a dark energy equation of state parameter is defined by a dark energy adiabatic sound speed and a dark…
In a previous work it was shown that by considering the quantum nature of the gravitational field mediator, it is possible to introduce the momentum energy of the graviton into the Einstein equations as an effective cosmological constant.…
We perform fits of unconventional dark energy models to the available data from high-redshift supernovae, distant galaxies and baryon oscillations. The models are based either on brane cosmologies or on Liouville strings in which a…
We consider a model-independent approach to constrain the equivalence redshift, $z_{eq}$, at which dark energy and the total matter (cold dark matter and baryonic) equate their magnitudes. To this aim, in the context of a homogeneous and…
A supersymmetric hybrid potential model with low energy supersymmetry breaking scale ($ M_{S}\sim 1-10 Tev$) is presented for both dark matter and dark energy. Cold dark matter is associated with a light modulus field ($\sim 10-100 Mev$)…
One of the greatest challenges of science is to understand the current accelerated expansion of the Universe. In this work, we show that by considering the quantum nature of the gravitational field, its wavelength can be associated with an…
It was found that the model with interaction between cold dark matter (CDM) and dark energy (DE) proportional to the energy density of CDM $\rho_m$ and constant equation of state of DE $w_d$ suffered from instabilities of the density…
I consider a scenario proposed by Fardon, Nelson and Weiner where dark energy and neutrinos are connected. As a result, neutrino masses are not constant but depend on the neutrino number density. By examining the full equation of state for…
Interesting discrepancies in cosmological parameters are challenging the success of the $\Lambda$CDM model. Direct measurements of the Hubble constant $H_0$ using Cepheid variables and supernovae turn out to be higher than inferred from the…
The cosmological constant, which was introduced by Einstein a century ago to allow for a static universe, experienced a revival two decades ago under the label dark energy as a parameter to model the observed accelerated expansion of the…
I briefly review the cosmological constant problem and the issue of dark energy (or quintessence). Within the framework of quantum field theory, the vacuum expectation value of the energy momentum tensor formally diverges as $k^4$. A cutoff…
Hubble constant($H_0$) tension and tension in the matter fluctuation amplitude ($s_8$) are fascinating puzzles in cosmology nowadays. Phantom dynamical dark energy model (PDDE), also known as little sibling of the big rip is an abrupt event…