Related papers: Accelerated expansion from braneworld models with …
The search for the physical mechanism underlying the observational evidence for the acceleration of the recent universe is a compelling goal of modern fundamental cosmology. Here we quantitatively study a class of homogeneous and isotropic…
It is a fact that the universe lives on a Gravitational Wave Background (GWB), which it may be in the form of extra energy, which is not contained in Einstein's field equations. In \cite{Matos:2021jef}, a new model was developed to explain…
Modeling of matter bounce in $f(R,T)$ gravity has been presented with no violation of the null energy condition. Only a closed universe with negative pressure is allowed in good agreement with some recent observations which favor a universe…
The cosmological constant, i.e., the energy density stored in the true vacuum state of all existing fields in the Universe, is the simplest and the most natural possibility to describe the current cosmic acceleration. However, despite its…
Brane-world models offer the possibility of explaining the late acceleration of the universe via infra-red modifications to General Relativity, rather than a dark energy field. However, one also expects ultra-violet modifications to General…
We consider a single 3-brane sitting in between two different five dimensional spacetimes. On each side of the brane, the bulk is a solution to Gauss-Bonnet gravity, although the bare cosmological constant, funda mental Planck scale, and…
Here, RS-II model of brane-gravity is considerd for phantom universe using non-linear equation of stste. Phantom fluid is known to violate the weak energy condition. In this paper, it is found that this characteristic of phantom energy is…
In the context of f(R, T) gravity theory for the flat Friedmann Lemaitre Robertson Walker (FLRW) model, the accelerating expansion of the universe is investigated using a specific form of the emergent Hubble parameter. Datasets from H(z),…
We consider a cosmological model dominated by stiff fluid with a constant bulk viscosity. We classify all the possible cases of the universe predicted by the model and analyzing the scale factor, density as well as the curvature scalar. We…
The cosmological observation indicates that the effective equation of state parameter $w_{eff}$ varies with $z$: It changes from $w_{eff}>-1$ to $w_{eff}<-1$ at $z\sim 0.2$. We investigate under which condition it exhibits such behaviors…
Recently there have been claims on model-independent evidence of dynamical dark energy. Herein we consider a fairly general class of cosmological models with a time-evolving cosmological term of the form $\Lambda(H)=C_0+C_H H^2+C_{\dot{H}}…
Current universe (assumed here to be normal matter on the brane) is pressureless from observations. In this case the energy condition is $\rho_0\geq0$ and $p_0=0$. By using this condition, brane models can be distinguished. Then, assuming…
The idea that the vacuum energy density $\rho_{\Lambda}$ could be time dependent is a most reasonable one in the expanding Universe; in fact, much more reasonable than just a rigid cosmological constant for the entire cosmic history. Being…
Cosmic acceleration is explained quantitatively, purely in general relativity, as an apparent effect due to quasilocal gravitational energy differences that arise in the decoupling of bound systems from the global expansion of the universe.…
In this work, I develop an alternative explanation for the acceleration of the cosmic expansion, which seems to be a result of recent high redshift Supernova data. In the current interpretation, this cosmic acceleration is explained by…
We use the Gu-Huang model for a special case when the universe is seven dimensional. In the core of extra dimension we place a modified Gidding-Strominger wormhole. This wormhole is separated by a thin wall from the extra dimensional space.…
We show that, under general assumptions, in six-dimensional brane-world models with compactified large extra dimensions, the energy density of brane oscillations scales as that of cold dark matter and its present value is compatible with…
We propose an interpretation for the cosmological constant problem based on modeling the universe as a 3-brane embedded in the bulk of 5-dimensional supergravity with hypermultiplets. When solving the modified Friedmann equations the…
It has recently been pointed out that global solutions of Einstein's equations for a 3-brane universe embedded in 4 spatial dimensions give rise to a Friedmann equation of the form H ~ rho on the brane, instead of the usual H ~ (rho)^{1/2},…
Brane world cosmologies seem to provide an alternative explanation for the present accelerated stage of the Universe with no need to invoke either a cosmological constant or an exotic \emph{quintessence} component. In this paper we…