Particle horizon

About: Particle horizon is a research topic. Over the lifetime, 2096 publications have been published within this topic receiving 69137 citations.

Evolution of the universe in inverse and ln f ( R ) gravity

Abstract: Evolution of the universe is discussed in the framework of f(R) theory of gravity. The deceleration parameter is used to interpret various phases of the universe. We investigate the future evolution of the flat FRW universe by using observationally viable f(R) models. A numerical technique is applied to solve the evolution equation in terms of Hubble parameter which is used to explore late time acceleration of the universe. Some novel and interesting results based on the choice of coupling parameters in gravitational action are obtained. We can conclude that the considered f(R) models imply unification of matter dominated epoch with present accelerating phase of the universe.

Higher Dimensional Cosmological Model With Gravitational and Cosmological "Constants"

Abstract: In this paper we have considered a cosmological model representing a flat viscous universe with variable G and Λ in the context of higher dimensional spacetime. It has been observed that in this model the particle horizon exists and the cosmological term varies as inverse square of time. The deceleration parameter and temperature are well within the observational limits. The model indicates matter and entropy generation in the early stages of the universe. Further, it is shown that our model generates all models obtained by Arbab and Singh et al. in four-dimensional space-time.

Reconstruction of Scalar Field Dark Energy Models in Kaluza—Klein Universe

Abstract: This paper is devoted to study the modified holographic dark energy model by taking its different aspects in the flat Kaluza—Klein universe. We construct the equation of state parameter which evolutes the universe from quintessence region towards the vacuum. It is found that the modified holographic model exhibits instability against small perturbations in the early epoch of the universe but becomes stable in the later times. We also develop its correspondence with some scalar field dark energy models. It is interesting to mention here that all the results are consistent with the present observations.

A Weyl-Dirac Cosmological Model with DM and DE

Abstract: In the Weyl-Dirac (W-D) framework a spatially closed cosmological model is considered. It is assumed that the space-time of the universe has a chaotic Weylian microstructure but is described on a large scale by Riemannian geometry. Locally fields of the Weyl connection vector act as creators of massive bosons having spin 1. It is suggested that these bosons, called weylons, provide most of the dark matter in the universe. At the beginning the universe is a spherically symmetric geometric entity without matter. Primary matter is created by Dirac's gauge function very close to the beginning. In the early epoch, when the temperature of the universe achieves its maximum, chaotically oriented Weyl vector fields being localized in micro-cells create weylons. In the dust dominated period Dirac's gauge function is giving rise to dark energy, the latter causing the cosmic acceleration at present. This oscillatory universe has an initial radius identical to the Plank length = 1.616 exp (-33) cm, at present the cosmic scale factor is 3.21 exp (28) cm, while its maximum value is 8.54 exp (28) cm. All forms of matter are created by geometrically based functions of the W-D theory.