Thermodynamics in the Evolution of the Dark Universe

We present a model of the universe based on the theory that space consists of energy quanta. We use the thermodynamics of an ideal gas to elucidate the composition, accelerated expansion, and the nature of dark energy and dark matter without an Inflation stage. From wave-particle duality, the space quanta can be treated as an ideal gas. The universe started from an atomic size volume at very high temperature and pressure. Upon expansion and cooling, phase transitions occurred to form fundamental particles, and matter. These nucleate and grew into stars, galaxies, and clusters due to gravity. From cooling data, a thermodynamic phase diagram of cosmic composition was constructed which yielded a correlation between dark energy and the energy of space. Using Friedmann’s equations, our model fits well the Williamson Microwave Anisotropy Platform (WMAP) data on cosmic composition with an equation of state parameter, w = -0.7. The dominance of dark energy started at 7.25 × 109 years, in good agreement with Baryon Oscillation Spectroscopic Survey (BOSS) measurements. The expansion of space can be attributed to a scalar space field. Dark Matter is identified as a plasma form of matter similar to that which existed before recombination and during the reionization epoch. The expansion of the universe was adiabatic and decelerating during the first 7 billion years after the Big Bang;it accelerated thereafter. A negative pressure for Dark Energy is required to sustain it;this is consistent with the theory of General Relativity and energy conservation. We propose a mechanism for the acceleration as due to the consolidation of matter to form Black Holes and other massive compact objects. The resulting reduction in gravitational potential energy feeds back energy for the acceleration. It is not due to a repulsive form of gravity. Our Quantum Space model fits well the observed behavior of the universe and resolves the outstanding questions in Inflationary Big Bang Theory.

Energy of the Gravitational Field as an Equivalent of the Dark Energy of the Universe

Determination of the structural foundations and parameters of the Universe is an important urgent task since it enables us to understand and explain the structure and basic parameters of the material world. Herewith, it is necessary to be aware of modern problems of physics and possible ways to solve them. Among such problems, hypotheses concerning dark matter and the energy of the Universe occupy an important place. However, the determination of their on the basis of modern theories still leads to abstract equations that do not give concrete results;therefore, they have a level of hypotheses. A number of initial scientific propositions based on this abstract of mathematical dependencies have controversial meanings. Elimination of this disadvantage is the main goal of the work performed. Its main difference and scientific novelty are the justification of the energy parameters of the gravitational field of the Universe, the magnitude of which can replace its dark energy and dark mass. The solution to this problem is justified by strict physical dependencies, which are obtained on the basis of fundamental physical constants. It is an urgent and important scientific and applied problem, since it develops knowledge about the gravitational field and the material world in general. The performed work is based on the methods of deduction and induction in the research of the material world based on the application of the well-known reliable laws of physics and the general principles of the development of the theory of knowledge. Other research methods are still unknown, since the work performed is associated with new scientific discoveries, the search for which is difficult to formalize by technique methods. The results of the study consist of the analysis of wave, force and energy parameters of the relict gravitational field of the Universe. The calculated value of this energy is 1.58 × 1070 J. This energy is enough to cover the amount of dark energy and mass in the Universe, which casts doubt on their existence. Conclusions: This paper can supplement previously performed research on the dark mass and energy of the Universe, which requires further for their reconciliation.

Constraints on ultracompact minihalos using neutrino signals from gravitino dark matter decay

Ultracompact dark matter minihalos （UCMHs） would be formed during the early universe if there were large density perturbations. If dark matter can decay into particles described by the standard model, such as neutrinos, these objects would become potential astrophysical sources of emission which could be detected by in- struments such as IceCube. In this paper, we investigate neutrino signals from nearby UCMHs due to gravitino dark matter decay and compare these signals with the back- ground neutrino flux which is mainly from the atmosphere to obtain constraints on the abundance of UCMHs.

Mutually interacting tachyon dark energy with variable G and Λ

We consider a tachyonic scalar field as a model of dark energy with interac- tion between components in the case of variable G and A. We assume a fiat Universe with a specific form of scale factor and study cosmological parameters numerically and graphically. Statefinder analysis is also performed. For a particular choice of in- teraction parameters we succeed in obtaining an analytical expression of densities. We find that our model will be stable at the late stage but there is an instability in the early Universe, so we propose this model as a realistic model of our Universe.

Pairwise Velocity Statistics of Dark Halos

We have accurately evaluated the halo pairwise velocity dispersion and the halo mean streaming velocity in the LCDM model (the fiat ω0 = 0.3 model) using a set of high-resolution N-body simulations. Based on the simulation results, we have developed a model for the pairwise velocity dispersion of halos. Our model agrees with the simulation results over all scales we studied. We have also tested the model of Sheth et al. for the mean streaming motion of halos derived from the pair-conservation equation. We found that their model reproduces the simulation data very well on large scale, but under-predicts the streaming motion on scales r < 10 h-1 Mpc. We have introduced an empirical relation to improve their model. These improved models are useful for predicting the redshift correlation functions and the redshift power spectrum of galaxies if the halo occupation number model, e.g. the cluster weighted model, is given for the galaxies.

The moment generating function of pairwise velocity in the context of redshift space distortion

We study the connections between the pairwise velocity moment generating function G(k_(‖),r)and redshift space distortion(RSD)modeling.Here k_(‖)is the Fourier wavevector parallel to the line of sight,and r is the pair separation vector.We demonstrate its usage by two examples.(1)Besides the known relations between G and the RSD power spectrum(and the correlation function),we propose a new RSD statistics Ps(k_(‖),r_(丄))whose connection to G is convenient to evaluate numerically.(2)We then develop a fast method to numerically evaluate G,and apply it to a high resolution N-body simulation.We find that G(ln G)shows complicated dependence on k_(‖)beyond the linear and quadratic dependencies.This not only shows inaccuracy in some existing models and identifies sources of inaccuracy but also provides possible ways of improving the RSD modeling.Consequently,more comprehensive investigations on G are needed to fully explore the usage of G in RSD modeling.

Primordial black holes

Primordial black holes （PBHs） are a profound signature of primordial cosmological structures and provide a theoretical tool to study nontrivial physics of the early Universe. The mechanisms of PBH formation are discussed and observational constraints on the PBH spectrum, or effects of PBH evaporation, are shown to restrict a wide range of particle physics models, predicting an enhancement of the ultraviolet part of the spectrum of density perturbations, early dust-like stages, first order phase transitions and stages of superheavy metastable particle dominance in the early Universe. The mechanism of closed wall contraction can lead, in the inflationary Universe, to a new approach to galaxy formation, involving primordial clouds of massive BHs created around the intermediate mass or supermassive BH and playing the role of galactic seeds.