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 Testing a Dilaton Gravity Model Using Nucleosynthesis

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
S. Boran ◽  
E. O. Kahya
Keyword(s):  
Steady State ◽  
Gravity Model ◽  
Big Bang ◽  
Universe Model ◽  
Light Elements ◽  
Dilaton Gravity ◽  
Microwave Background ◽  
Big Bang Nucleosynthesis ◽  
Higher Dimensional ◽  
State Universe

Big bang nucleosynthesis (BBN) offers one of the most strict evidences for theΛ-CDM cosmology at present, as well as the cosmic microwave background (CMB) radiation. In this work, our main aim is to present the outcomes of our calculations related to primordial abundances of light elements, in the context of higher dimensional steady-state universe model in the dilaton gravity. Our results show that abundances of light elements (primordial D,3He,4He, T, and7Li) are significantly different for some cases, and a comparison is given between a particular dilaton gravity model andΛ-CDM in the light of the astrophysical observations.

scholarly journals A BGO set-up for the direct measurement of the D(p,γ)3He fusion cross section at LUNA

2020 ◽  
Vol 1668 (1) ◽  
pp. 012028
Author(s):  
Viviana Mossa
Keyword(s):  
Cross Section ◽  
Cosmic Time ◽  
Fusion Cross Section ◽  
Big Bang ◽  
Baryon Density ◽  
Reaction Cross ◽  
Big Bang Nucleosynthesis ◽  
Primordial Abundance ◽  
Set Up ◽  
The Big Bang

Abstract The Big Bang Nucleosynthesis (BBN) describes the production of light nuclides occurred during the first minutes of cosmic time. It started with the accumulation of deuterium, whose primordial abundance is sensitive to the universal baryon density and to the amount of relativistic particles. Currently the main source of uncertainty to an accurate theoretical deuterium abundance evaluation is due to the poor knowledge of the D(p, γ)3He cross section at BBN energies. The present work wants to describe one of the two experimental approaches proposed by the LUNA collaboration, whose goal is to measure with unprecedented precision, the reaction cross section in the energy range 30 < Ecm[keV] < 300.

scholarly journals Big Bang Nucleosynthesis

2002 ◽  
Vol 187 ◽  
pp. 1-15
Author(s):  
D.N. Schramm
Keyword(s):  
Systematic Error ◽  
Big Bang ◽  
Baryon Density ◽  
Galactic Evolution ◽  
Big Bang Nucleosynthesis ◽  
X Ray ◽  
Baryonic Density ◽  
The Big Bang ◽  
The Universe

Big Bang Nucleosynthesis (BBN) is on the verge of undergoing a transformation now that extragalactic deuterium is being measured. Previously, the emphasis was on demonstrating the concordance of the Big Bang Nucleosynthesis model with the abundances of the light isotopes extrapolated back to their primordial values using stellar and Galactic evolution theories. Once the primordial deuterium abundance is converged upon, the nature of the field will shift to using the much more precise primordial D/H to constrain the more flexible stellar and Galactic evolution models (although the question of potential systematic error in 4He abundance determinations remains open). The remarkable success of the theory to date in establishing the concordance has led to the very robust conclusion of BBN regarding the baryon density. The BBN constraints on the cosmological baryon density are reviewed and demonstrate that the bulk of the baryons are dark and also that the bulk of the matter in the universe is non-baryonic. Comparison of baryonic density arguments from Lyman-α clouds, x-ray gas in clusters, the Sunyaev-Zeldovich effect, and the microwave anisotropy are made and shown to be consistent with the BBN value.

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 Primordial nucleosynthesis

2017 ◽  
Vol 26 (08) ◽  
pp. 1741002 ◽  
Author(s):  
Alain Coc ◽  
Elisabeth Vangioni
Keyword(s):  
Cross Sections ◽  
Nuclear Physics ◽  
Big Bang ◽  
Microwave Background ◽  
Big Bang Nucleosynthesis ◽  
Primordial Nucleosynthesis ◽  
Expansion Of The Universe ◽  
Sensitivity Studies ◽  
Global Agreement ◽  
The Big Bang

Primordial nucleosynthesis, or big bang nucleosynthesis (BBN), is one of the three evidences for the big bang model, together with the expansion of the universe and the cosmic microwave background. There is a good global agreement over a range of nine orders of magnitude between abundances of 4He, D, 3He and 7Li deduced from observations, and calculated in primordial nucleosynthesis. However, there remains a yet-unexplained discrepancy of a factor [Formula: see text], between the calculated and observed lithium primordial abundances, that has not been reduced, neither by recent nuclear physics experiments, nor by new observations. The precision in deuterium observations in cosmological clouds has recently improved dramatically, so that nuclear cross-sections involved in deuterium BBN needs to be known with similar precision. We will briefly discuss nuclear aspects related to the BBN of Li and D, BBN with nonstandard neutron sources, and finally, improved sensitivity studies using a Monte Carlo method that can be used in other sites of nucleosynthesis.

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 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].

Helium in Three H II Galaxies and the Helium Abundance

1990 ◽  
Vol 8 (3) ◽  
pp. 243-245
Author(s):  
B. E. J. Pagel ◽  
E. A. Simonson
Keyword(s):  
Particle Physics ◽  
Hubble Constant ◽  
Big Bang ◽  
Density Fluctuations ◽  
Microwave Background ◽  
Big Bang Nucleosynthesis ◽  
Hadron Phase ◽  
The Mean ◽  
The Big Bang ◽  
The Universe

Extended abstractThe mass-fraction Y of helium in the interstellar medium is between 0.22 and 0.30 wherever it has been measured and it is believed to be the sum of two components: YP from Big Bang nucleosynthesis (BBNS) at about 100 s after the Big Bang (ABB) and a temperature near 0.1 MeV, and ΔY due to processing in stars. Precise measurements of Yp, along with balances of trace elements D, 3He, 7Li also resulting from BBNS, provide important tests of BBNS theory and of parameters of cosmology and particle physics, notably the contribution ΩBO of baryons to the mean density of matter in the universe (in units of the closure density), the number Nv of light neutrino flavours (or families of quarks and leptons) and the half-life т½ of the neutron (Shaver et al. 1983; Yang et al. 1984; Boesgaard and Steigman 1985). Figure 1 shows the predicted abundances from Standard BBNS theory (SBBN) as a function of η = μB/nλ the ratio of baryons to photons (unchanged since e± annihilation a few seconds ABB), which is proportional (through the known temperature of the microwave background) to ΩBOh20 where h0 is the Hubble constant in units of 100 km s−1 Mpc−1. SBBN theory (which assumes a homogeneous Friedmann universe and small lepton numbers), when combined with reasonable ideas on Galactic chemical evolution that predict a primordial (D + 3He)/H ratio below 10−4, imply that η ≥ 3 × 10−10 (shown by the tall vertical line in Fig. 1), which in turn implies YP≥0.210 if Nv = 3 and т½≥10.4 minutes. But this limit can be somewhat relaxed if т½ is smaller (current measurements permit values down to 9.0 minutes, e.g. Last et al. 1988) and/or if the quark-hadron phase transition around 200 MeV is first-order and leads to significant density fluctuations (Kurki-Sunonio et al. 1989; Reeves 1989).

scholarly journals Relativistic Cosmology with an Introduction to Inflation

Universe ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 276
Author(s):  
Muhammad Zahid Mughal ◽  
Iftikhar Ahmad ◽  
Juan Luis García Guirao
Keyword(s):  
Standard Model ◽  
Early Universe ◽  
Large Scale ◽  
Initial Conditions ◽  
Big Bang ◽  
Relativistic Cosmology ◽  
The Standard Model ◽  
Big Bang Model ◽  
The Big Bang ◽  
The Universe

In this review article, the study of the development of relativistic cosmology and the introduction of inflation in it as an exponentially expanding early phase of the universe is carried out. We study the properties of the standard cosmological model developed in the framework of relativistic cosmology and the geometric structure of spacetime connected coherently with it. The geometric properties of space and spacetime ingrained into the standard model of cosmology are investigated in addition. The big bang model of the beginning of the universe is based on the standard model which succumbed to failure in explaining the flatness and the large-scale homogeneity of the universe as demonstrated by observational evidence. These cosmological problems were resolved by introducing a brief acceleratedly expanding phase in the very early universe known as inflation. The cosmic inflation by setting the initial conditions of the standard big bang model resolves these problems of the theory. We discuss how the inflationary paradigm solves these problems by proposing the fast expansion period in the early universe. Further inflation and dark energy in fR modified gravity are also reviewed.

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