Big-bang nucleosynthesis

Primordial, non-standard, production during Big Bang Nucleosynthesis (BBN) the decay/annihilation of some massive particle (e.g. neutralino) releases energetic nucleons/photons which produce 3He or 3H by spallation/photodisinte-gration of 4He, while subsequent fusion reactions between 4He and 3He or 3H ere-... 

Big Bang nucleosynthesis produced only H and He atoms with a little Li, from which nuclei the first generation of stars must have formed. Large clouds of H and He when above the Jeans Mass condensed under the influence of gravitational attraction until they reached the temperatures and densities required for a protostar to form, as outlined. Nuclear fusion powers the luminosity of the star and also results in the formation of heavier atomic nuclei. 

Big Bang nucleosynthesis (cosmic nucleosynthesis) Proton-proton cycle Triple He collisions Alpha capture CNO cycle Neutron capture High-energy photon collisions produce antimatter-matter pairs. This leads to H,D, He and some Li nuclei Hydrogen burning to produce He 12C production Addition of 4He to the nucleus Production of 13C, 13N, 14N and 150 Post-Fe nuclei... 

Big Bang nucleosynthesis The energy-matter conversion at the beginning of the Universe forming the elements H, He and Li directly. 

S. Sarkar, in Rep. Prog. Phys., 59, 1493, 1996, gives a detailed discussion of Big Bang nucleosynthesis and physics beyond the Standard Model. 

Deuterium discovered in interstellar gas (Copernicus satellite) and quantitatively estimated in early Solar System, restricting baryonic density in Big Bang nucleosynthesis (BBNS) theory. 

Estimates of primordial helium and deuterium abundance with Big Bang nucleosynthesis theory limit number of light neutrino families to 4 or less (Schramm et al). 

Two arguments support the idea that some invisible substance exists in the Uruverse. The first is dynamic. It starts from observation of motions under the effect of gravity. The second is related to Big Bang nucleosynthesis, i.e. nuclear cosmology, which combines cosmology and nuclear physics. 

The first stage of stellar nucleosynthesis, which is still occurring in stars such as our sun, is hydrogen burning. In hydrogen burning, protons are converted to 4He nuclei. Since there are no free neutrons present, the reactions differ from those of Big Bang nucleosynthesis. The first reaction that occurs is... 

Big Bang nucleosynthesis is responsible for the synthesis of hydrogen and helium and some of the 7Li. (Stellar nucleosynthesis in main sequence stars transforms about 7% of the hydrogen into 4He.) However, neither stellar nucleosynthesis or Big Bang nucleosynthesis can produce the observed abundances of Li, Be, and B. Consequently, the abundances of Li, Be, and B are suppressed by a factor of 106 relative to the abundances of the neighboring elements (Fig. 12.2). 

The paper is organized as follows in section 2, we briefly review the geometry and dynamics of the Universe and then give the Einstein-Friedman-Lemaitre (hereafter EEL) equations section 3 introduces some important quantities needed for observations in section 4, we rapidly present some solutions of the EEL equations, i.e. some cosmological models in section 5, the Standard Big Bang Nucleosynthesis Model is described while section 6 shows a statement of observations of primordial abundances in section 7, we confront the predictions of the Standard Big Bang Nucleosynthesis (hereafter SBBN) model to the observations of the primordial abundances a brief conclusion is... 

On this figure 2, we see the four plots of the primordial abundances of 4He, D, 3He and 7Li as predicted by the standard model of Big Bang nucleosynthesis (Buries, Nollett Turner, 2001). We see also the boxes which indicate the observed fight elements ... 

Big Bang nucleosynthesis suggests a low-density Universe with the density parameter il m 0.05 the smoothness of the Hubble flow also favours a low-density Universe. 

By the end of 1970s most objections against the dark matter hypothesis were rejected. In particular, luminous populations of galaxies have found to have lower mass-to-luminosity ratio than expected previously, thus the presence of extra dark matter both in galaxies and clusters has been confirmed. However, the nature of dark matter and its purpose was not yet clear. Also it was not clear how to explain the Big Bang nucleosynthesis constraint on the low density of matter, and the smoothness of the Hubble flow. 

The last parameter of big bang nucleosynthesis. .. is being pinned down by measurements of the deuterium abundance in high-redshift hydrogen clouds. 

S. Turner, Sharpening the Predictions of Big-Bang Nucleosynthesis, Physical Review Letters 82, 4176-4179 (1999), p. 4176. 

Baryonic candidates were traditionally brown dwarfs, old white dwarfs, neutron stars, and stellar mass black holes. Both they and the new ones are subject to the big bang nucleosynthesis constraint above others might accrete matter, thus radiating, absorb at some wavelengths, or otherwise reveal themselves. 

Depending on which estimate is considered most reliable, Yp either agrees with the best current estimate of D/H under standard Big Bang nucleosynthesis (for Yp = 0.244, or it does not). 

I give here a brief summary of the main steps in the Big Bang nucleosynthesis. 

One of the major achievements in cosmology is that it can account simultaneously for the primordial abundances of H, D, 3He, 4IIc and 7Li but only for a low density universe. The comparison between the observed primordial abundances and the Big Bang nucleosynthesis calculations can allow to impose constraints upon the baryon to photon ratio (rj) in the universe. In particular, for a baryon to photon ratio r/ 3 10 10 the baryonic density parameter of the universe is (Peacock, 1999) ... 

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