Related papers: Rendering Dark Energy Void
In view of late-time cosmic acceleration, a dark energy cosmological model is revisited wherein Einstein's cosmological constant is considered as a candidate of dark energy. Exact solution of Einstein field equations (EFEs) is derived in a…
We investigate Dark Energy by associating it with vacuum energy or Cosmological constant ${\Lambda}$ which is taken to be dynamic in nature. Our approach is phenomenological and falls within the domain of variable-$\Lambda$ Cosmology.…
We consider holographic cosmological models of dark energy in which the infrared cutoff is set by the Hubble's radius. We show that any interacting dark energy model, regardless of its detailed form, can be recast as a non interacting model…
In this study, we introduce a novel late-time effective dark energy model characterized by a quadratic equation of state (EoS) and rigorously examine its observational constraints. Initially, we delve into the background dynamics of this…
In the realm of thermodynamics of apparent horizon, we construct a dark energy (DE) model from 4-parameter generalized entropy of apparent horizon in a spatially non-flat universe. In particular, considering a non-zero spatial curvature of…
Observations restrict the parameter space of Holographic Dark Energy (HDE) so that a turning point in the Hubble parameter $H(z)$ is inevitable. Concretely, cosmic microwave background (CMB), baryon acoustic oscillations (BAO) and Type Ia…
Decaying vacuum models are a class of models that incorporate the vacuum energy density as a time-evolving entity that has the potential to explain the entire evolutionary history of the universe in a single framework. A general solution to…
A higher value of Hubble constant has been obtained from measurements with nearby Type Ia supernovae, than that obtained at much higher redshift. With the peculiar motions of their hosts, we find that the matter content at such low redshift…
The tension between the value of the Hubble constant $H_0$ determined from local supernovae data and the one inferred from the cosmic microwave background based on the $\Lambda$CDM cosmological model may indicate the need for new physics.…
In this work we examine what are the cosmological implications of allowing the geometrical curvature density to behave independently from the energy density contents. Using the full data extracted by Planck mission from CMB, combined with…
The expansion rate of the Universe changes with time, initially slowing (decelerating) when the universe was matter dominated, because of the mutual gravitational attraction of all the matter in it, and more recently speeding up…
Following the holographic principle, which suggests that the energy density of dark energy may be proportional inversely to the area of the event horizon of the Universe, we have proposed a new energy density of dark energy through the…
We consider a holographic cosmological model in which the infrared cutoff is fixed by the Ricci's length and dark matter and dark energy do not evolve separately but interact non-gravitationally with one another. This substantially…
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…
In this work the Vacuum Energy Density Problem or Dark Energy Problem is studied on the basis of the earlier results by the author within the scope of the Holographic Principle. It is demonstrated that the previously introduced deformed…
We find that if we live at the center of an inhomogeneity with total density contrast of roughly 0.1, dark energy is not a cosmological constant at 95% confidence level. Observational constraints on the equation of state of dark energy, w,…
When using distance measurements to probe spatial curvature, the geometric degeneracy between curvature and dark energy in the distance-redshift relation typically requires either making strong assumptions about the dark energy evolution or…
A system of effective Einstein equations for spatially averaged scalar variables of inhomogeneous cosmological models can be solved by providing a `cosmic equation of state'. Recent efforts to explain Dark Energy focus on `backreaction…
We present the idea that replacing the cosmological constant $\Lambda$ in the $\Lambda$CDM model by a distribution of walls, with very low tension compared to what one would expect from new physics, could help explaining the tension in the…
A six parameter cosmological model, involving a vacuum energy density that is extremely tiny compared to fundamental particle physics scales, describes a large body of increasingly accurate astronomical data. In a first part of this brief…