scholarly journals X-Ray Observations of the Hot Intergalactic Medium

1998 ◽  
Vol 188 ◽  
pp. 193-196
Author(s):  
Q. Daniel Wang
Keyword(s):  
Intergalactic Medium ◽  
Big Bang ◽  
Gas Temperature ◽  
Big Bang Nucleosynthesis ◽  
Filamentary Structure ◽  
Heating Source ◽  
Chemical Enrichment ◽  
Shock Heating ◽  
The Big Bang ◽  
The Universe

A definite prediction from recent N-body/hydro simulations of the structure formation of the universe is the presence of a diffuse hot intergalactic medium (HIGM; e.g., Ostriker & Cen 1996). The filamentary structure of the today's universe, as seen in various galaxies surveys, is thought to be a result of the gravitational collapse of materials from a more-or-less uniform and isotropic early universe. During the collapse, shock-heating can naturally raise gas temperature to a range of 105 – 107 K. Feedbacks from stars may also be an important heating source and may chemically enrich the HIGM. The understanding of the heating and chemical enrichment of the IGM is critical for studying the structure and evolution of clusters of galaxies, which are nearly virialized systems (e.g., Kaiser 1991; David, Jones, & Forman 1996). Most importantly, the HIGM may explain much of the missing baryon content required by the Big Bang nucleosynthesis theories (e.g., Copi, Schramm, & Turner 1995); the total visible mass in galaxies and in the hot intracluster medium together is known to account for ≲ 10% of the baryon content (e.g., Persic & Salucci 1992).

scholarly journals Big Bang Nucleosynthesis in Visible and Hidden-Mirror Sectors

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Paolo Ciarcelluti
Keyword(s):  
Dark Matter ◽  
Building Blocks ◽  
Big Bang ◽  
Dark Matter Candidate ◽  
Big Bang Nucleosynthesis ◽  
Enhanced Production ◽  
The Standard Model ◽  
The Big Bang ◽  
The Universe ◽  
Mirror Matter

One of the still viable candidates for the dark matter is the so-called mirror matter. Its cosmological and astrophysical implications were widely studied, pointing out the importance to go further with research. In particular, the Big Bang nucleosynthesis provides a strong test for every dark matter candidate, since it is well studied and involves relatively few free parameters. The necessity of accurate studies of primordial nucleosynthesis with mirror matter has then emerged. I present here the results of accurate numerical simulations of the primordial production of both ordinary nuclides and nuclides made of mirror baryons, in presence of a hidden mirror sector with unbroken parity symmetry and with gravitational interactions only. These elements are the building blocks of all the structures forming in the Universe; therefore, their chemical composition is a key ingredient for astrophysics with mirror dark matter. The production of ordinary nuclides shows differences from the standard model for a ratio of the temperatures between mirror and ordinary sectorsx=T′/T≳0.3, and they present an interesting decrease of the abundance ofLi7. For the mirror nuclides, instead, one observes an enhanced production ofHe4, which becomes the dominant element forx≲0.5, and much larger abundances of heavier elements.

A critical analysis of the Big Bang Nucleosynthesis

2019 ◽  
Vol 34 (24) ◽  
pp. 1950194 ◽  
Author(s):  
Tahani R. Makki ◽  
Mounib F. El Eid ◽  
Grant J. Mathews
Keyword(s):  
Critical Analysis ◽  
Big Bang ◽  
Early Evolution ◽  
Big Bang Nucleosynthesis ◽  
Evolution Of The Universe ◽  
Chemical Potentials ◽  
Primordial Abundance ◽  
The Big Bang ◽  
The Universe

Standard Big Bang Nucleosynthesis (SBBN) represents one of the basic tools to understand the early evolution of the universe. In this paper, we reanalyze this process to focus on the so-called lithium problem. 7Li is overproduced during SBBN compared to its primordial abundance as obtained from observations. For this reason, we extend the scenarios of SBBN in two directions: (i) equating all neutrino chemical potentials and including more neutrino families, (ii) varying neutrino chemical potentials independently. Since the so-called cosmological lithium problem is not resolved on nuclear/astrophysical ground, we argue that this problem should be examined by invoking nonstandard assumptions.

scholarly journals The Spectrum of Gravitational Waves, Their Overproduction in Quintessential Inflation and Its Influence in the Reheating Temperature

Universe ◽  
2020 ◽  
Vol 6 (6) ◽  
pp. 87
Author(s):  
Jaume Haro Cases ◽  
Llibert Aresté Saló
Keyword(s):  
Phase Transition ◽  
Gravitational Waves ◽  
Particle Production ◽  
Big Bang ◽  
Kinetic Regime ◽  
Big Bang Nucleosynthesis ◽  
Inflaton Field ◽  
The Big Bang ◽  
The Universe

One of the most important issues in an inflationary theory as standard or quintessential inflation is the mechanism to reheat the universe after the end of the inflationary period in order to match with the Hot Big Bang universe. In quintessential inflation two mechanisms are frequently used, namely the reheating via gravitational particle production which is, as we will see, very efficient when the phase transition from the end of inflation to a kinetic regime (all the energy of the inflaton field is kinetic) is very abrupt, and the so-called instant preheating which is used for a very smooth phase transition because in that case the gravitational particle production is very inefficient. In the present work, a detailed study of these mechanisms is done, obtaining bounds for the reheating temperature and the range of the parameters involved in each reheating mechanism in order that the Gravitational Waves (GWs) produced at the beginning of kination do not disturb the Big Bang Nucleosynthesis (BBN) success.

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 An overvew of nucleosynthesis and Cosmological parameters and observations using CMB and redshift

2020 ◽  
Author(s):  
Vaibhav Kalvakota
Keyword(s):  
Cosmological Parameters ◽  
Baryon Number ◽  
Big Bang ◽  
Big Bang Nucleosynthesis ◽  
Symmetry Violation ◽  
Time Period ◽  
Symmetry Problem ◽  
Cp Symmetry ◽  
The Big Bang ◽  
The Universe

The Big Bang nucleosynthesis has some elements in it which are of utmost importance to understand how the Universe is as we know it. Our consideration in this paper will primarily be on TGUT, the temperature (and also therefore time period) when all the forces behaved under the laws of the same Unification theory. Next, we will consider the QCD transition phase, when the behaviour of matter (quarks, gluons) was quite important in the structure of the Big Bang model. Finally, we will consider the Baryon symmetry problem, where we will discuss the inequality of matter and anti-matter. We will also briefly discuss the synthesis of Baryons and leptons (labelled Baryonsynthesis and leptonsynthesis respectively), the Sakharov outlines and the Baryon number, and its conditions with the outline under Thermodynamic equilibrium departure and the C-CP symmetry violation conditions.

scholarly journals Introduction to big bang nucleosynthesis and modern cosmology

2017 ◽  
Vol 26 (08) ◽  
pp. 1741001 ◽  
Author(s):  
Grant J. Mathews ◽  
Motohiko Kusakabe ◽  
Toshitaka Kajino
Keyword(s):  
Nuclear Reactions ◽  
Big Bang ◽  
Cosmological Models ◽  
Big Bang Nucleosynthesis ◽  
Primordial Nucleosynthesis ◽  
Current State ◽  
Modern Cosmology ◽  
Basic Equations ◽  
The Big Bang ◽  
The Universe

Primordial nucleosynthesis remains as one of the pillars of modern cosmology. It is the testing ground upon which many cosmological models must ultimately rest. It is our only probe of the universe during the important radiation-dominated epoch in the first few minutes of cosmic expansion. This paper reviews the basic equations of space-time, cosmology, and big bang nucleosynthesis. We also summarize the current state of observational constraints on primordial abundances along with the key nuclear reactions and their uncertainties. We summarize which nuclear measurements are most crucial during the big bang. We also review various cosmological models and their constraints. In particular, we analyze the constraints that big bang nucleosynthesis places upon the possible time variation of fundamental constants, along with constraints on the nature and origin of dark matter and dark energy, long-lived supersymmetric particles, gravity waves, and the primordial magnetic field.

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 Big Bang Nucleosynthesis, Population III, and Stellar Genetics in the Galactic Halo

2002 ◽  
Vol 19 (2) ◽  
pp. 238-245 ◽  
Author(s):  
Sean G. Ryan
Keyword(s):  
Galactic Halo ◽  
Stellar Populations ◽  
Big Bang ◽  
Big Bang Nucleosynthesis ◽  
Chemical Signatures ◽  
The Galaxy ◽  
Successive Generations ◽  
The Big Bang ◽  
The Universe ◽  
Population Iii

AbstractThe diverse isotopic and elemental signatures produced in different nucleosynthetic sites are passed on to successive generations of stars. By tracing these chemical signatures back through the stellar populations of the Galaxy, it is possible to unravel its nucleosynthetic history and even to study stars which are now extinct. This review considers recent applications of ‘stellar genetics’ to examine the earliest episodes of nucleosynthesis in the universe, in Population iii stars and the Big Bang.

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