Particle horizon

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

Generalized Ideal Gas Equations for Structureful Universe

Abstract: We have derived generalized ideal gas equations for a structureful universe consistingof all forms of matters. We have assumed a universe that contains superclusters. Superclusters arethen made of clusters. Each cluster can be further divided into smaller ones and so on. We havederived an expression for the entropy of such a universe. Our model is rather independent of thegeometry of the intermediate clusters. Our calculations are valid for a non-interacting universewithin non-relativistic limits. We suggest that structure formation can reduce the expansion rateof the universe.

The Density of the Universe

Abstract: Having collected all the available information on the distribution of galaxies in space and on intergalactic material, we are able to attack the problem of the density of the universe. This density is one of the four fundamental parameters observable within a gigaparsec and contributing to cosmology. The other three are the distance scale, the Hubble constant which we have already studied, and the age of the universe which is the subject of the next chapter.

Evolution of density and velocity profiles of matter in large voids

Abstract: We analyse the evolution of cosmological perturbations which leads to the formation of large voids in the distribution of galaxies. We assume that perturbations are spherical and all components of the Universe - radiation, matter and dark energy - are continuous media with ideal fluid energy-momentum tensors, which interact only gravitationally. Equations of the evolution of perturbations in the comoving to cosmological background reference frame for every component are obtained from equations of conservation and Einstein's ones and are integrated by modified Euler method. Initial conditions are set at the early stage of evolution in the radiation-dominated epoch, when the scale of perturbation is mush larger than the particle horizon. Results show how the profiles of density and velocity of matter in spherical voids with different overdensity shells are formed.