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Particle horizon
About: Particle horizon is a research topic. Over the lifetime, 2096 publications have been published within this topic receiving 69137 citations.
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TL;DR: In this paper, a cosmological model based on an inhomogeneous D3-brane moving in an AdS5 × S5 bulk is introduced, and it is shown that the early stage accelerating phase ends in a dust-dominated FRW homogeneous universe.
Abstract: A cosmological model based on an inhomogeneous D3-brane moving in an AdS5 × S5 bulk is introduced. Although there are no special points in the bulk, the brane universe has a centre and is isotropic around it. The model has an accelerating expansion and its effective cosmological constant is inversely proportional to the distance from the centre, giving a possible geometrical origin for the smallness of a present-day cosmological constant. Besides, if our model is considered as an alternative of early-time acceleration, it is shown that the early stage accelerating phase ends in a dust-dominated FRW homogeneous universe. Mirage-driven acceleration thus provides a dark matter component for the brane universe final state. We finally show that the model fulfils the current constraints on inhomogeneities.
5 citations
TL;DR: In this paper, the authors studied a spatially flat Friedmann-Lema?tre?Robertson?Walker (FLRW) cosmological model with an additional assumption that the universe is filled with barotropic causal bulk viscous fluid.
Abstract: We have studied a spatially flat Friedmann?Lema?tre?Robertson?Walker (FLRW) cosmological model with an additional assumption that the universe is filled with barotropic causal bulk viscous fluid. The bulk viscous coefficient of the fluid is related to the energy density and relaxation time by the relation . We have used a truncated version of the transport equation for the viscous pressure. The expansion rate of such a spatially flat FLRW universe is governed by the well-known modified Painlev??Ince equation. We find that the Lie symmetry corresponding to scale invariance gives the power-law solution for this model equation from invariant curve condition. For the value of , our result satisfies the present experimental value of the deceleration parameter (q) for . The result obtained for the relaxation time which is of the order of the Hubble time supports the necessary condition for successful inflation. Our study not only shows the role of the bulk viscosity for the present accelerating expansion but also predicts an age of around , which solves the age problem of the present universe.
5 citations
TL;DR: In this article, the authors discuss how parameters describing inflation in the very early universe may be related to primordial perturbation spectra, and propose a model of the early universe at high energies.
Abstract: I discuss how parameters describing inflation in the very early universe may be related to primordial perturbation spectra. Precision observations of anisotropies in the cosmic microwave background (CMB) such as those provided by the WMAP satellite offer an unprecedented window onto the physics of the very early universe. To theorists exploring speculative models of physics at high energies, the CMB offers us the chance to put our ideas to the test.
5 citations
TL;DR: In this paper, the entropy evolution in the early universe was investigated by computing the change of the entanglement entropy in Freedmann-Robertson-Walker quantum cosmology in the presence of particle horizon.
Abstract: We investigate the entropy evolution in the early universe by computing the change of the entanglement entropy in Freedmann-Robertson-Walker quantum cosmology in the presence of particle horizon. The matter is modeled by a Chaplygin gas so as to provide a smooth interpolation between inflationary and radiation epochs, rendering the evolution of entropy from early time to late time trackable. We found that soon after the onset of the inflation, the total entanglement entropy rapidly decreases to a minimum. It then rises monotonically in the remainder of the inflation epoch as well as the radiation epoch. Our result is in qualitative agreement with the area law of Ryu and Takayanagi including the logarithmic correction. We comment on the possible implication of our finding to the cosmological entropy problem.
5 citations
TL;DR: Inflationary models also predict the existence of a relic gravity wave background as discussed by the authors, and the discovery of large angle anisotropies in the CMB having the scale invariant spectrum predicted by inflationary models has fuelled the hope that the inflationary scenario may indeed provide the correct description of the very early Universe.
Abstract: The inflationary Universe resolves some of the most outstanding issues of standard cosmology including the horizon and flatness problems and the origin of density fluctuations in the Universe. Inflationary models also predict the existence of a relic gravity wave background. Both gravity waves and density fluctuations induce fluctuations in the cosmic microwave background (CMB), the discovery of large angle anisotropies in the CMB having the scale invariant spectrum predicted by inflationary models has fuelled the hope that the inflationary scenario may indeed provide the correct description of the very early Universe. Upcoming large scale galaxy surveys (SDSS & 2dF) and CMB missions (MAP, Planck Surveyor) will further probe the inflationary scenario by throwing light on the origin and evolution of large scale structure in the Universe.
5 citations