Related papers: Evolution of primordial H2 for different cosmologi…
We investigate the possible impact of diffusion on the abundance of helium and other primordial elements during formation of the first structures in the early Universe. We consider the primary collapse of a perturbation and subsequent…
At the early stage of the Universe-evolution there were no stars and no galaxies, but only a uniform hot plasma consisting of free electrons and free nuclei. The Universe temperature was determined by the Stefan-Boltzmann law of…
We review the relevance of H2 molecules for structure formation in cosmology. Molecules are important at high redshifts, when the first collapsed structures appear with typical temperatures of a few hundred Kelvin. In these chemically…
The study of primordial chemistry of molecules adresses a number of interesting questions pertaining to the thermal balance of collapsing molecular protoclouds. In numerous astrophysical cases molecular cooling and heating influence…
The synthesis of helium in the early Universe depends on many input parameters, including the value of the gravitational coupling during the period when the nucleosynthesis takes place. We compute the primordial abundance of helium as…
This dissertation aims to deepen the understanding of the primordial composition of the Universe in the temperature range 300 MeV>T>0.02 MeV. I exploit known properties of elementary particles and apply methods of kinetic theory and…
Formation and evolution of water in the Solar System and the origin of water on Earth constitute one of the most interesting questions in astronomy. The prevailing hypothesis for the origin of water on Earth is by delivery through…
We consider an isotropic homogeneous cosmological model with five interacting elements: first, the dynamic aether presented by a unit timelike vector field, second, the pseudoscalar field describing an axionic component of the dark matter,…
The connection between cosmological observations and neutrino physics is discussed in detail. Neutrinos decouple from thermal contact in the early Universe at a temperature of order 1 MeV which coincides with the temperature where light…
The evolution of a flat, isotropic and homogeneous universe is studied. The background geometry in the early phases of the universe is conjectured to be filled with causal bulk viscous cosmological fluid and dark energy. The energy density…
The "dark age" of the Universe is generally pointed out as the period between the recombination epoch and the horizon of current observations (z=5-6). The arrow of time in the cosmic history describes the progression from simplicity to…
The dark Universe corresponds to the period between the thermal decoupling matter-radiation and the formation of the first objects. During this epoq, molecules can appeared. In this talk, I will recall the nucleosynthesis processes, then…
The physical ingredients to describe the epoch of cosmological recombination are amazingly simple and well-understood. This fact allows us to take into account a very large variety of processes, still finding potentially measurable…
The history of the Universe after its first second is now tested by high quality observations of light element abundances and temperature anisotropies of the cosmic microwave background. The epoch of the first second itself has not been…
We present a review on the determination of the primordial helium abundance, Yp, based on the study of hydrogen and helium recombination lines in extragalactic H II regions. We also discuss the observational determinations of the increase…
Our goal is to study the effects of the UV radiation from the first stars, quasars and hypothetical Super Heavy Dark Matter (SHDM) particle decays on the formation of primordial bound objects in the Universe. We trace the evolution of a…
Assuming that the matter filling the background geometry in the Early Universe was a free gas and no phase transitions took place, we discuss the thermodynamics of this closed system using classical approaches. We found that essential…
The main goal of this work is to calculate the contributions to the cosmological recombination spectrum due to bound-bound transitions of helium. We show that due to the presence of helium in the early Universe unique features appear in the…
The primordial nucleosinthesys of the element can be influenced by the transitions of phase that take place after the Big Bang, such as the QCD transition. In order to study the effect of this phase transition, in this work we compute the…
We investigate nucleosynthesis and element formation in the early universe in the framework of higher dimensional cosmology. For this purpose we utilize a previous solution of the present author, which may be termed as the generalized…