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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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Posted Content•
TL;DR: In this article, an alternative cosmological concept is discussed, which is called the ground universe and is a self-creating due to a balance of annihilation and pair creation in the interuniverse infinite space.
Abstract: Super-high energy corpuscular and gamma rays as well as cosmic high--power density sources are hard to explain in a galaxy model framework.
Attempts to include some of those phenomena in the Standard Cosmological Model also encounter serious difficulties. In the present paper an alternative cosmological concept is discussed. There are several features in it. First of all, the whole Universe (Grand Universe) is a multitude of typical universes, like ours, evenly made of either matter or antimatter, hence, there is no violation of the baryon symmetry on the largest scale.
Second, high-energy phenomena are the result of matter-antimatter annihilation processes in a typical universe evolution. Finally, the Ground Universe is a self-creating due to a balance of annihilation and pair creation in the inter-universe infinite space. This concept and its consistence with the major observational data are discussed in detail.
01 Jan 2015
TL;DR: In this paper, the cosmological effect of neutrinos on the evolution of the universe was investigated in a study of the average behavior of the ΛCDM universe.
Abstract: The cosmological effect of sterile neutrinos is estimated in a study of the average behavior of the ΛCDM universe. Dark matter is assumed to be composed of neutralinos and it is argued that dark energy may result from conformal variations of the metric. The eventual presence of sterile neutrinos does not noticeably change the evolution of the universe and we find that their density at primordial nucleosynthesis is consistent with predictions when the sterile neutrinos are in temperature equilibrium with the rest of the universe at the end of inflation.
Journal Article•
TL;DR: In this paper, a cosmological model with very simple solutions characterized by string clouds was proposed, assuming self-similar symmetry for a Kantowski- Sachs spacetime and the gravitational effects of the cosmic strings.
Abstract: We study a cosmological model with very simple solutions characterized by string clouds. Assuming self-similar symmetry for a Kantowski- Sachs spacetime we study the gravitational effects of the cosmic strings. It is also assumed that the primitive universe enters in a false vacuum-dominated era, accelerating the expansion in a time period of the order of 10 -35 sec (a phase transition), satisfying all the energy conditions. Finally, we examine the possibility that in the last stages of this evolution, the geometry of the universe could be flat.
TL;DR: In this paper, the authors applied the Hubble size criterion and the event horizon criterion to several dark energy models to discuss the problem of future inflation of the universe, and they found that the acceleration has not lasted long enough to confirm the onset of inflation by present observations for the dark energy model with constant equation of state, the holographic light energy model and the generalized Chaplygin gas (GCG) model.
Abstract: We consider the possibility of observing the onset of the late time inflation of our patch of the Universe. The Hubble size criterion and the event horizon criterion are applied to several dark energy models to discuss the problem of future inflation of the Universe. We find that the acceleration has not lasted long enough to confirm the onset of inflation by present observations for the dark energy model with constant equation of state, the holographic dark energy model and the generalized Chaplygin gas (GCG) model. For the flat Lambda CDM model with Omega(m0) = 0.3, we find that if we use the Hubble size criterion, we need to wait until the a(v) which is the scale factor at the time when the onset of inflation is observed reaches 3.59 times of scale factor a(T) when the onset of inflation is observed reaches 3.59 times of the scale factor a(T) when the Universe started acceleration, and we need to wait until a(v) = 2.3a(T) to see the onset of inflation if we use the event horizon criterion. For the flat holographic dark energy model with d = 1, we find that a(v) = 3.46a(T) with the Hubble horizon and a(v) = 2.34a(T) with the event horizon, respectively. For the flat GCG model with the best supernova fitting parameter alpha = 1.2, we find that a(v) = 5.50a(T) with the Hubble horizon and a(v) = 2.08a(T) with the event horizon, respectively.
Posted Content•
TL;DR: In this article, a cosmologic model with variable "constants" c, H, and G is constructed and it is shown that with an appropriate variation of the Boltzmann "constant" k the thermal evolution of the universe is similar to the standard model.
Abstract: Proceeding from a homogeneous and isotropic Friedmann universe a conceptional problem concerning light propagation in an expanding universe is brought up. As a possible solution of this problem it is suggested that light waves do not scale with R(t). With the aid of a Generalized Equivalence Principle a cosmologic model with variable "constants" c, H, and G is constructed. It is shown that with an appropriate variation of the Boltzmann "constant" k the thermal evolution of the universe is similar to the standard model. It is further shown that this model explains the cosmological redshift as well as certain problems of the standard model (horizon, flatness, accelerated expansion of the universe).
PACS numbers: 98.80.Bp, 98.80.Hw, 04.20.Cv.
Keywords: cosmology, velocity of light, expansion.