Related papers: Cosmological k-essence condensation
We obtain lagrangian for $k$-essence scalar field $\phi(r,t)$ with scalar curvature $k$ of Friedmann-Lemaitre-Robertson-Walker (FLRW) metric . Obtained lagrangian has two generalised co-ordinates $\phi$ and logarithm of scale factor ($q=\ln…
In this paper we present a cosmological model arising from a non-conservative gravitational theory proposed in [PRD 95, 101501(R) (2017)]. The novel feature where comparing with previous implementations of dissipative effects in gravity is…
The mysterious `dark energy' needed to explain the current observations, poses a serious confrontation between fundamental physics and cosmology. The present crisis may be an outcome of the (so far untested) prediction of the general theory…
For a large class of mass-varying massive gravity models, the graviton mass cannot provide the late-time cosmic expansion of the universe due to its vanishing at late time. In this work, we propose a new class of mass-varying massive…
In 1919 Einstein tried to solve the problem of the structure of matter by assuming that the elementary particles are held together solely by gravitational forces. In addition, Einstein also assumed the presence inside matter of…
We investigate the emergent laws of gravity when Dark Energy and the de Sitter space-time are modelled as a critical Bose-Einstein condensate of a large number of soft gravitons $N_{\rm G}$. We argue that this scenario requires the presence…
An introduction to solutions of the Einstein equations defining cosmological models with accelerated expansion is given. Connections between mathematical and physical issues are explored. Theorems which have been proved for solutions with…
We study spatially flat isotropic universes driven by k-essence. It is shown that Friedmann and k-field equations may be analytically integrated for arbitrary k-field potentials during evolution with a constant baryotropic index. It follows…
We consider the rapidly-oscillating part of a $q$-field in a cosmological context and find that its energy density behaves in the same way as a cold-dark-matter component, namely proportional to the inverse cube of the cosmic scale factor.
In the standard model of cosmology, the present evolution of the Universe is determined by the presence of two components of unknown nature. One of them is referenced as ``dark matter'' to justify the fact that it behaves cosmologically…
We investigate a coupled quintessence cosmological model in which a dark-energy scalar field with an exponential potential interacts directly with a dark-matter fluid through a dissipative term inspired by warm inflation. The evolution…
We investigate the tachyon condensation process in the effective theory with non-vanishing minimum potential and its implications to cosmology. It is shown that the tachyon condensation on an unstable three-brane described by this modified…
We investigate the cosmological perturbation dynamics for a universe consisting of pressureless baryonic matter and a viscous fluid, the latter representing a unified model of the dark sector. In the homogeneous and isotropic background the…
Cosmology and particle physics are deeply interrelated. Among the common problems are dark energy, dark matter and baryon asymmetry of the Universe. We discuss these problems in general terms, and concentrate on several particular…
In a recent paper we showed that a quintessence scalar field plus a dissipative matter fluid can drive late cosmic accelerated expansion and simultaneously solve the coincidence problem [1]. In this brief report we extend this result to the…
We consider the growth of cosmological perturbations to the energy density of dark matter during matter domination when dark matter is a scalar field that has undergone Bose-Einstein condensation. We study these inhomogeneities within the…
A cosmological model is proposed for the current Universe consisted of non-interacting baryonic matter and interacting dark components. The dark energy and dark matter are coupled through their effective barotropic indexes, which are…
Given that the dark matter and dark energy in the universe affect cosmological observables only gravitationally, their phenomenology may be described by a single stress energy tensor. True unification however requires a theory that…
In the same way as the realization of some of the famous gedanken experiments imagined by the founding fathers of quantum mechanics has recently led to the current renewal of the interpretation of quantum physics, it seems that the most…
We discuss thermodynamic properties of dark energy using the formalism of field theory at finite temperature. In particular, we apply our formalism to a purely kinetic type of k-essence. We show quite generally that the entropy associated…