scholarly journals Effects of transient nonthermal particles on the big bang nucleosynthesis

2020 ◽  
Vol 29 (03) ◽  
pp. 2050012
Author(s):  
Tae-Sun Park ◽  
Kyung Joo Min ◽  
Seung-Woo Hong
Keyword(s):  
Reaction Rates ◽  
Big Bang ◽  
Temporal Region ◽  
Temporal Position ◽  
Strongly Correlated ◽  
Light Elements ◽  
Big Bang Nucleosynthesis ◽  
Wide Range ◽  
The Big Bang ◽  
Nonthermal Particles

The effects of introducing a small amount of nonthermal distribution (NTD) of elements in big bang nucleosynthesis (BBN) are studied by allowing a fraction of the NTD to be time-dependent so that it contributes only during a certain period of the BBN evolution. The fraction is modeled as a Gaussian-shaped function of [Formula: see text], where [Formula: see text] is the temperature of the cosmos, and thus the function is specified by three parameters; the central temporal position, the width and the magnitude. The change in the average nuclear reaction rates due to the presence of the NTD is assumed to be proportional to the Maxwellian reaction rates but with temperature [Formula: see text], [Formula: see text] being another parameter of our model. By scanning a wide four-dimensional parametric space at about half a million points, we have found about 130 points with [Formula: see text], at which the predicted primordial abundances of light elements are consistent with the observations. The magnitude parameter [Formula: see text] of these points turns out to be scattered over a very wide range from [Formula: see text] to [Formula: see text], and the [Formula: see text]-parameter is found to be strongly correlated with the magnitude parameter [Formula: see text]. The temperature region with [Formula: see text] or the temporal region [Formula: see text][Formula: see text]s seems to play a central role in lowering [Formula: see text].

scholarly journals Big-Bang nucleosynthesis: Constraints on nuclear reaction rates, neutrino degeneracy, inhomogeneous and Brans–Dicke models

2017 ◽  
Vol 26 (08) ◽  
pp. 1741003 ◽  
Author(s):  
Riou Nakamura ◽  
Masa-Aki Hashimoto ◽  
Ryotaro Ichimasa ◽  
Kenzo Arai
Keyword(s):  
Cosmological Constant ◽  
Nuclear Reaction ◽  
Recent Progress ◽  
Reaction Rates ◽  
Big Bang ◽  
Big Bang Nucleosynthesis ◽  
Friedmann Model ◽  
Theory Of Gravitation ◽  
The Big Bang

We review the recent progress in the Big-Bang nucleosynthesis which includes the standard and nonstandard theory of cosmology, effects of neutrino degeneracy, and inhomogeneous nucleosynthesis within the framework of a Friedmann model. As for a nonstandard theory of gravitation, we adopt a Brans–Dicke theory which incorporates a cosmological constant. We constrain various parameters associated with each subject.

scholarly journals A new tension in the cosmological model from primordial deuterium?

2021 ◽  
Vol 502 (2) ◽  
pp. 2474-2481
Author(s):  
Cyril Pitrou ◽  
Alain Coc ◽  
Jean-Philippe Uzan ◽  
Elisabeth Vangioni
Keyword(s):  
Big Bang ◽  
Reaction Cross ◽  
Light Elements ◽  
Neutron Lifetime ◽  
Microwave Background ◽  
Big Bang Nucleosynthesis ◽  
Baryonic Density ◽  
The Status ◽  
Big Bang Model ◽  
The Big Bang

ABSTRACT Recent measurements of the D(p,γ)3He nuclear reaction cross-section and of the neutron lifetime, along with the reevaluation of the cosmological baryon abundance from cosmic microwave background (CMB) analysis, call for an update of abundance predictions for light elements produced during the big-bang nucleosynthesis (BBN). While considered as a pillar of the hot big-bang model in its early days, BBN constraining power mostly rests on deuterium abundance. We point out a new ≃1.8σ tension on the baryonic density, or equivalently on the D/H abundance, between the value inferred on one hand from the analysis of the primordial abundances of light elements and, on the other hand, from the combination of CMB and baryonic oscillation data. This draws the attention on this sector of the theory and gives us the opportunity to reevaluate the status of BBN in the context of precision cosmology. Finally, this paper presents an upgrade of the BBN code primat.

scholarly journals Underground Nuclear Astrophysics: Present and future of the LUNA experiment

2019 ◽  
Vol 209 ◽  
pp. 01043
Author(s):  
Carlo Gustavino
Keyword(s):  
Nuclear Astrophysics ◽  
Reaction Rates ◽  
Big Bang ◽  
Scientific Program ◽  
Thermonuclear Reaction ◽  
Big Bang Nucleosynthesis ◽  
Celestial Bodies ◽  
Deep Underground ◽  
The Big Bang ◽  
Nuclear Processes

The evolution of celestial bodies is regulated by gravitation and thermonuclear reaction rates, while the Big Bang nucleosynthesis is the result of nuclear processes in a rapidly expanding Universe. The LUNA Collaboration has shown that, by exploiting the ultra low background achievable deep underground, it is possible to study the relevant nuclear processes down to the nucleosynthesis energy inside stars and during the first minutes of Universe. In this paper the main results of LUNA are overviewed, as well as the scientific program the forthcoming 3.5 MV underground accelerator.

scholarly journals Insights Into Chemical Reactions at the Beginning of the Universe: From HeH+ to H3+

2021 ◽  
Vol 9 ◽  
Author(s):  
Soumya Ranjan Dash ◽  
Tamal Das ◽  
Kumar Vanka
Keyword(s):  
Big Bang ◽  
Light Elements ◽  
Hydrogen Atoms ◽  
Big Bang Nucleosynthesis ◽  
Special Cases ◽  
The Big Bang ◽  
The Universe ◽  
Dynamics Method ◽  
Positively Charged ◽  
Dense Atmosphere

At the dawn of the Universe, the ions of the light elements produced in the Big Bang nucleosynthesis recombined with each other. In our present study, we have tried to mimic the conditions in the early Universe to show how the recombination process would have led to the formation of the first ever formed diatomic species of the Universe: HeH+, as well as the subsequent processes that would have led to the formation of the simplest triatomic species: H3+. We have also studied some special cases: higher positive charge with fewer number of hydrogen atoms in a dense atmosphere, and the formation of unusual and interesting linear, dicationic He chains beginning from light elements He and H in a positively charged atmosphere. For all the simulations, the ab initio nanoreactor (AINR) dynamics method has been employed.

scholarly journals Bayesian Estimation of the D(p,γ)3He Thermonuclear Reaction Rate

2021 ◽  
Vol 923 (1) ◽  
pp. 49
Author(s):  
Joseph Moscoso ◽  
Rafael S. de Souza ◽  
Alain Coc ◽  
Christian Iliadis
Keyword(s):  
Reaction Rates ◽  
Big Bang ◽  
Baryon Density ◽  
Thermonuclear Reaction ◽  
Big Bang Nucleosynthesis ◽  
Highly Sensitive ◽  
Theoretical Predictions ◽  
Reliable Knowledge ◽  
Percent Accuracy ◽  
The Big Bang

Abstract Big bang nucleosynthesis (BBN) is the standard model theory for the production of light nuclides during the early stages of the universe, taking place about 20 minutes after the big bang. Deuterium production, in particular, is highly sensitive to the primordial baryon density and the number of neutrino species, and its abundance serves as a sensitive test for the conditions in the early universe. The comparison of observed deuterium abundances with predicted ones requires reliable knowledge of the relevant thermonuclear reaction rates and their corresponding uncertainties. Recent observations reported the primordial deuterium abundance with percent accuracy, but some theoretical predictions based on BBN are in tension with the measured values because of uncertainties in the cross section of the deuterium-burning reactions. In this work, we analyze the S-factor of the D(p,γ)3He reaction using a hierarchical Bayesian model. We take into account the results of 11 experiments, spanning the period of 1955–2021, more than any other study. We also present results for two different fitting functions, a two-parameter function based on microscopic nuclear theory and a four-parameter polynomial. Our recommended reaction rates have a 2.2% uncertainty at 0.8 GK, which is the temperature most important for deuterium BBN. Differences between our rates and previous results are discussed.

scholarly journals Revised uncertainties in Big Bang Nucleosynthesis

2017 ◽  
Vol 26 (08) ◽  
pp. 1741008 ◽  
Author(s):  
M. Foley ◽  
N. Sasankan ◽  
M. Kusakabe ◽  
G. J. Mathews
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Analysis ◽  
Reaction Rates ◽  
Big Bang ◽  
Effective Number ◽  
Big Bang Nucleosynthesis ◽  
The Big Bang

Big Bang Nucleosynthesis (BBN) explores the first few minutes of nuclei formation during the Big Bang. We present updated 2[Formula: see text] for the abundances of the four primary light nuclides — D, 3He, 4He, and 7Li — in BBN. A modified standard BBN code was used in a Monte Carlo analysis of the nucleosynthesis uncertainties as a function of the baryon-to-photon ratio. Reaction rates were updated to those of NACRE, REACLIB, and [Formula: see text]-Matrix calculations. The results were then used to derive a new constraint on the effective number of neutrinos.

scholarly journals Elements in the Cosmos: Origin of the Light Elements

1991 ◽  
Vol 145 ◽  
pp. 3-12
Author(s):  
Hubert Reeves
Keyword(s):  
Cosmic Ray ◽  
Big Bang ◽  
Light Elements ◽  
Big Bang Nucleosynthesis ◽  
Hadron Phase ◽  
Iron Deficient ◽  
The Galaxy ◽  
Galactic Cosmic Ray ◽  
The Big Bang ◽  
Theoretical Developments

In the first part of this paper, a review is given of the situation of the Big Bang nucleosynthesis of the nuclides D, 3He, 4He and 7Li, taking into account the latest experimental data (number of neutrino species, lifetime of the neutron) and theoretical developments (quark-hadron phase transition). In the second part. I review the process of Galactic Cosmic Ray formation of lithium, beryllium and boron throughout the life of the galaxy, taking advantage of recent measurements of Be and Li in iron deficient stars.

scholarly journals Measurement and Implications of the Cosmic Microwave Background Spectrum

1996 ◽  
Vol 168 ◽  
pp. 17-29
Author(s):  
John C. Mather
Keyword(s):  
Background Radiation ◽  
Far Infrared ◽  
Big Bang ◽  
Scale Invariant ◽  
Background Spectrum ◽  
Nasa Goddard Space ◽  
Wide Range ◽  
Infrared Background ◽  
Microwave Radiometers ◽  
The Big Bang

The Cosmic Background Explorer (COBE) was developed by NASA Goddard Space Flight Center to measure the diffuse infrared and microwave radiation from the early universe. It also measured emission from nearby sources such as the stars, dust, molecules, atoms, ions, and electrons in the Milky Way, and dust and comets in the Solar System. It was launched 18 November 1989 on a Delta rocket, carrying one microwave instrument and two cryogenically cooled infrared instruments. The Far Infrared Absolute Spectrophotometer (FIRAS) mapped the sky at wavelengths from 0.01 to 1 cm, and compared the CMBR to a precise blackbody. The spectrum of the CMBR differs from a blackbody by less than 0.03%. The Differential Microwave Radiometers (DMR) measured the fluctuations in the CMBR originating in the Big Bang, with a total amplitude of 11 parts per million on a 10° scale. These fluctuations are consistent with scale-invariant primordial fluctuations. The Diffuse Infrared Background Experiment (DIRBE) spanned the wavelength range from 1.2 to 240 μm and mapped the sky at a wide range of solar elongation angles to distinguish foreground sources from a possible extragalactic Cosmic Infrared Background Radiation (CIBR). In this paper we summarize the COBE mission and describe the results from the FIRAS instrument. The results from the DMR and DIRBE were described by Smoot and Hauser at this Symposium.

scholarly journals Li isotopes in metal-poor halo dwarfs: a more and more complicated story

2009 ◽  
Vol 5 (S268) ◽  
pp. 201-210
Author(s):  
Monique Spite ◽  
François Spite
Keyword(s):  
Cosmic Rays ◽  
Big Bang ◽  
The Other ◽  
Big Bang Nucleosynthesis ◽  
Lithium Abundance ◽  
The Galaxy ◽  
Li Isotope ◽  
Low Metallicity ◽  
The Big Bang ◽  
Early Galaxy

AbstractThe nuclei of the lithium isotopes are fragile, easily destroyed, so that, at variance with most of the other elements, they cannot be formed in stars through steady hydrostatic nucleosynthesis.The 7Li isotope is synthesized during primordial nucleosynthesis in the first minutes after the Big Bang and later by cosmic rays, by novae and in pulsations of AGB stars (possibly also by the ν process). 6Li is mainly formed by cosmic rays. The oldest (most metal-deficient) warm galactic stars should retain the signature of these processes if, (as it had been often expected) lithium is not depleted in these stars. The existence of a “plateau” of the abundance of 7Li (and of its slope) in the warm metal-poor stars is discussed. At very low metallicity ([Fe/H] < −2.7dex) the star to star scatter increases significantly towards low Li abundances. The highest value of the lithium abundance in the early stellar matter of the Galaxy (logϵ(Li) = A(7Li) = 2.2 dex) is much lower than the the value (logϵ(Li) = 2.72) predicted by the standard Big Bang nucleosynthesis, according to the specifications found by the satellite WMAP. After gathering a homogeneous stellar sample, and analysing its behaviour, possible explanations of the disagreement between Big Bang and stellar abundances are discussed (including early astration and diffusion). On the other hand, possibilities of lower productions of 7Li in the standard and/or non-standard Big Bang nucleosyntheses are briefly evoked.A surprisingly high value (A(6Li)=0.8 dex) of the abundance of the 6Li isotope has been found in a few warm metal-poor stars. Such a high abundance of 6Li independent of the mean metallicity in the early Galaxy cannot be easily explained. But are we really observing 6Li?

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