Related papers: Backreaction from inhomogeneous matter fields duri…
We investigated the back reaction of cosmological perturbations on the evolution of the universe using the second order perturbation of the Einstein's equation. To incorporate the back reaction effect due to the inhomogeneity into the…
We discuss a field-theoretical approach based on variational principle to derive the field and hydrodynamic equations of motion of baryonic matter governed by cosmological perturbations of dark matter and dark energy. The action depends on…
A single fluid approximation which treats perturbations in baryons and dark matter as equal has sometimes been used to calculate the growth of linear matter density perturbations in the Universe. We demonstrate that properly accounting for…
In this letter we study a model of interaction between the scalar field and an inhomogeneous ideal fluid. We have considered two forms of the ideal fluid and a power law expansion for the scale factor. We have solved the equations for the…
Due to the non-commutation of spatial averaging and temporal evolution, inhomogeneities and anisotropies (cosmic structures) influence the evolution of the averaged Universe via the cosmological backreaction mechanism. We study the…
The cosmological backreaction arises when one directly averages the Einstein equations to recover an effective Robertson-Walker cosmology, rather than assuming a background a priori. While usually discussed in the context of dark energy,…
We consider an effective viscous pressure as the result of a backreaction of inhomogeneities within Buchert's formalism. The use of an effective metric with a time-dependent curvature radius allows us to calculate the luminosity distance of…
We establish a new self-consistent model in order to explain from a unified viewpoint two key features of the cosmological evolution: the inflation in the early Universe and the late-time accelerated expansion. The key element of this new…
The large-scale homogeneity and isotropy of the universe is generally thought to imply a well defined background cosmological model. It may not. Smoothing over structure adds in an extra contribution, transferring power from small scales up…
Recently, Bartelmann et al. presented a 'Kinetic Field Theory' (KFT) formalism to tackle the difficulties of large scale structure formation. In this approach, the dynamics of a non-equilibrium ensemble of classical particles are examined…
One of the biggest mysteries in cosmology is Dark Energy, which is required to explain the accelerated expansion of the universe within the standard model. But maybe one can explain the observations without introducing new physics, by…
We examine the growth of structure in three different cosmological models with interacting dark matter and vacuum energy. We consider the case of geodesic dark matter with zero sound speed, where the relativistic growing mode in…
It is commonly stated that we have entered the era of precision cosmology in which a number of important observations have reached a degree of precision, and a level of agreement with theory, that is comparable with many Earth-based physics…
Dark matter in the cosmological concordance model is parameterised by a single number, describing the covariantly conserved energy density of a non-relativistic fluid. Here we test this assumption in a model-independent and conservative way…
Cosmological models with two interacting fluids, each satisfying the strong energy condition, are studied in the framework of classical General Relativity. If the interactions are phenomenologically described by a power law in the scale…
A phenomenological formalism is presented in which the apparent acceleration of the universe is generated by cosmic structure formation, without resort to Dark Energy, modifications to gravity, or a local void. The observed acceleration…
A mildly inhomogeneous universe with a cosmological constant may look like it contains evolving dark energy. We show that could be the case by modelling the inhomogeneities and their effects in three different ways: as clumped matter…
We investigate the cosmological effects of neutrino lumps in Growing Neutrino Quintessence. The strongly non-linear effects are resolved by means of numerical N-body simulations which include relativistic particles, non-linear scalar field…
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…
We consider the evolution of linear perturbations in models with a nonminimal coupling between dark matter and scalar field dark energy. Growth of matter inhomogeneities in two examples of such models proposed in the literature are…