Related papers: Averaged Lema\^itre-Tolman-Bondi dynamics
We investigate the effect that the average backreaction of structure formation has on the dynamics of the cosmological expansion, within the concordance model. Our approach in the Poisson gauge is fully consistent up to second-order in a…
Backreaction effects of the large scale structure on the background dynamics have been claimed to lead to a renormalization of the background dynamics that may account for the late time acceleration of the cosmic expansion. This article…
The effective evolution of an inhomogeneous universe model in Einstein's theory of gravitation may be described in terms of spatially averaged scalar variables. This evolution can be modeled by solutions of a set of Friedmann equations for…
We have considered a cosmological model with a cosmological constant of the form $\Lambda=3\alpha\frac{\dot R^2}{R^2}+\bt\frac{\ddot R}{R} \alpha, \bt=\rm const.$ The cosmological constant is found to decrease as $t^{-2}$ and the rate of…
It is shown that the serious problem on the cosmological tension between the direct measurements of the Hubble constant at present and the constant derived from the Planck measurements of the CMB anisotropies can be solved by considering…
The near-zero value of the cosmological constant \Lambda in an equilibrium context may be due to the existence of a self-tuning relativistic vacuum variable q. Here, a cosmological nonequilibrium context is considered with a corresponding…
Perhaps the deepest mystery of our accelerating Universe in expansion is the existence of a tiny and rigid cosmological constant, $\Lambda$. Its size is many orders of magnitude below the expected one in the standard model of particle…
We discuss the averaging problem in general relativity, using the form of the macroscopic gravity equations in the case of spherical symmetry in volume preserving coordinates. In particular, we calculate the form of the correlation tensor…
An additional variation of the Einstein-Hilbert action with respect to the Planck mass provides a constraint on the average Ricci scalar that prevents vacuum energy from gravitating. Consideration of the evolution of the inhomogeneous…
We revisited the problem of describing, on average, a fractal distribution of matter using a Lemaitre-Tolman-Bondi (LTB) solution. Here we study the fractal structure of our local universe having a fractal dimension and a scale transition,…
It is well-known that spacetime averaging is an operation that does not commute with building the Einstein tensor. In the framework of Macroscopic gravity (MG), a covariant averaging procedure, this non-commutativity gives averaged field…
The sequestering mechanism has been proposed as a remedy to the old cosmological constant problem of the non-gravitating vacuum energy in the matter sector. Here it is shown that an extension of this global constraint mechanism arises…
Averaging in general relativity is a complicated operation, due to the general covariance of the theory and the non-linearity of Einstein's equations. The latter of these ensures that smoothing spacetime over cosmological scales does not…
The existence of 'peculiar' velocities due to the formation of cosmic structure marks a point of discord between the real Universe and the usually assumed Friedmann-Lema\'{i}tre-Robertson-Walker metric which accomodates only the smooth…
We investigate Lema\^itre-Tolman-Bondi (LTB) models, whose early time evolution and bang time are homogeneous and the distance - redshift relation and local Hubble parameter are inherited from the $\Lambda$CDM model. We show that the…
Spherical collapse predicts that a single value of the turnaround density (average matter density within the scale on which a structure detaches from the Hubble flow) characterizes all cosmic structures at the same redshift. It has been…
We point out that the standard formulation of the cosmological constant problem itself is problematic since it is trying to apply the very large scale homogeneous cosmological model to very small (Planck) scale phenomenon. At small scales,…
Cosmological backreaction corresponds to the effect of inhomogeneities of structure on the global expansion of the Universe. The main question surrounding this phenomenon is whether or not it is important enough to lead to measurable…
We perform numerical simulations of large scale structure evolution in an inhomogeneous Lemaitre-Tolman-Bondi (LTB) model of the Universe. We follow the gravitational collapse of a large underdense region (a void) in an otherwise flat…
Recent observational evidence of axially symmetric anisotropies in the local cosmic expansion rate motivates an investigation of whether they can be accounted for within the Lema\^itre-Tolman-Bondi (LTB) framework with an off-center…