Light element nucleosynthesis and estimates of the universal baryon density

International Nuclear Information System (INIS)

Mathews, G.J.; Viola, V.E.

1978-01-01

The present mean universal baryon density rho/sub b/, is of interest because it and the Hubble constant determine the curvature of the Universe. The available indicators of rho/sub b/ come from the present deuterium abundance, if it is assumed that ''big-bang'' nucleosynthesis must produce enough D to at least match the abundance of this nuclide in the interstellar medium. An alternative method utilizing the 7 Li/D ratio is used to evaluate rho/sub b/. With this method the difficulty associated with the astration process can be essentially canceled from the problem. The results obtained indicate an open Universe with a best guess for rho/sub b/ of 7.1 x 10 -31 g/cm 3 . 1 figure, 1 table

Towards the kinetic theory of inequilibrium cosmological nucleosynthesis

International Nuclear Information System (INIS)

Fillipov, S.S.; Sedelnikov, E.V.; Khlopov, M.Yu.

1993-07-01

The aim of the paper is to elaborate the framework for the possible effects of nucleosynthesis by inequilirbium particles on the radiation dominance stage. Based on such an analysis the sensitivity of the astrophysical data to the presence of the sources of inequilibrium particles in the early Universe can be studied, thus providing an effective tool to probe cosmological effects of syperhight energy physics. 6 refs

Large-basis shell-model technology in nucleosynthesis and cosmology

International Nuclear Information System (INIS)

Mathews, G.J.; Bloom, S.D.; Takahashi, K.; Fuller, G.M.; Hausman, R.F. Jr.

1985-05-01

We discuss various applications of the Lanczos method to describe properties of many-body microscopic systems in nucleosynthesis and cosmology. These calculations include: solar neutrino detectors; beta-decay of excited nuclear states; electron-capture rates during a core-bounce supernova; exotic quarked nuclei as a catalyst for hydrogen burning; and the quark-hadron phase transition during the early universe. 27 refs., 3 figs

Challenges to the standard model of Big Bang nucleosynthesis

International Nuclear Information System (INIS)

Steigman, G.

1993-01-01

Big Bang nucleosynthesis provides a unique probe of the early evolution of the Universe and a crucial test of the consistency of the standard hot Big Bang cosmological model. Although the primordial abundances of 2 H, 3 He, 4 He, and 7 Li inferred from current observational data are in agreement with those predicted by Big Bang nucleosynthesis, recent analysis has severely restricted the consistent range for the nucleon-to-photon ratio: 3.7 ≤ η 10 ≤ 4.0. Increased accuracy in the estimate of primordial 4 he and observations of Be and B in Pop II stars are offering new challenges to the standard model and suggest that no new light particles may be allowed (N ν BBN ≤ 3.0, where N ν is the number of equivalent light neutrinos). 23 refs

r-Process Nucleosynthesis in the Early Universe Through Fast Mergers of Compact Binaries in Triple Systems

Science.gov (United States)

Bonetti, Matteo; Perego, Albino; Capelo, Pedro R.; Dotti, Massimo; Miller, M. Coleman

2018-05-01

Surface abundance observations of halo stars hint at the occurrence of r-process nucleosynthesis at low metallicity ([Fe/H] scale of the inner compact object binaries. Our results are highly sensitive to the assumed initial distribution of the inner binary semi-major axes. Distributions with mostly wide compact object binaries are most affected by the third object, resulting in a strong increase (by more than a factor of 2) in the fraction of fast coalescences. If instead the distribution preferentially populates very close compact binaries, general relativistic precession prevents the third body from increasing the inner binary eccentricity to very high values. In this last case, the fraction of coalescing binaries is increased much less by tertiaries, but the fraction of binaries that would coalesce within 108 yr even without a third object is already high. Our results provide additional support to the compact-binary merger scenario for r-process nucleosynthesis.

On the chaoticity of active-sterile neutrino oscillations in the early universe

DEFF Research Database (Denmark)

Braad, Poul-Erik; Hannestad, Steen

2000-01-01

We have investigated the evolution of the neutrino asymmetry in active-sterile neutrino oscillations in the early universe. We find that there are large regions of parameter space where the asymmetry is extremely sensitive to variations in the initial asymmetry as well as the external parameters ...... asymmetry is stochastic. We discuss the implications of our findings for Big Bang nucleosynthesis (BBN) and the cosmic microwave background (CMB)....

Lepton asymmetry, neutrino spectral distortions, and big bang nucleosynthesis

Science.gov (United States)

Grohs, E.; Fuller, George M.; Kishimoto, C. T.; Paris, Mark W.

2017-03-01

We calculate Boltzmann neutrino energy transport with self-consistently coupled nuclear reactions through the weak-decoupling-nucleosynthesis epoch in an early universe with significant lepton numbers. We find that the presence of lepton asymmetry enhances processes which give rise to nonthermal neutrino spectral distortions. Our results reveal how asymmetries in energy and entropy density uniquely evolve for different transport processes and neutrino flavors. The enhanced distortions in the neutrino spectra alter the expected big bang nucleosynthesis light element abundance yields relative to those in the standard Fermi-Dirac neutrino distribution cases. These yields, sensitive to the shapes of the neutrino energy spectra, are also sensitive to the phasing of the growth of distortions and entropy flow with time/scale factor. We analyze these issues and speculate on new sensitivity limits of deuterium and helium to lepton number.

Constraining axion dark matter with Big Bang Nucleosynthesis

International Nuclear Information System (INIS)

Blum, Kfir; D'Agnolo, Raffaele Tito; Lisanti, Mariangela; Safdi, Benjamin R.

2014-01-01

We show that Big Bang Nucleosynthesis (BBN) significantly constrains axion-like dark matter. The axion acts like an oscillating QCD θ angle that redshifts in the early Universe, increasing the neutron–proton mass difference at neutron freeze-out. An axion-like particle that couples too strongly to QCD results in the underproduction of 4 He during BBN and is thus excluded. The BBN bound overlaps with much of the parameter space that would be covered by proposed searches for a time-varying neutron EDM. The QCD axion does not couple strongly enough to affect BBN

Constraining axion dark matter with Big Bang Nucleosynthesis

Science.gov (United States)

Blum, Kfir; D'Agnolo, Raffaele Tito; Lisanti, Mariangela; Safdi, Benjamin R.

2014-10-01

We show that Big Bang Nucleosynthesis (BBN) significantly constrains axion-like dark matter. The axion acts like an oscillating QCD θ angle that redshifts in the early Universe, increasing the neutron-proton mass difference at neutron freeze-out. An axion-like particle that couples too strongly to QCD results in the underproduction of 4He during BBN and is thus excluded. The BBN bound overlaps with much of the parameter space that would be covered by proposed searches for a time-varying neutron EDM. The QCD axion does not couple strongly enough to affect BBN.

Fred Hoyle, primary nucleosynthesis and radioactivity

Science.gov (United States)

Clayton, Donald D.

2008-10-01

Primary nucleosynthesis is defined as that which occurs efficiently in stars born of only H and He. It is responsible not only for increasing the metallicity of the galaxy but also for the most abundant gamma-ray-line emitters. Astrophysicists have inappropriately cited early work in this regard. The heavily cited B2FH paper (Burbidge et al., 1957) did not effectively address primary nucleosynthesis whereas Hoyle (Hoyle, 1954) had done so quite thoroughly in his infrequently cited 1954 paper. Even B2FH with Hoyle as coauthor seems strangely to not have appreciated what Hoyle (Hoyle, 1954) had achieved. I speculate that Hoyle must not have thoroughly proofread the draft written in 1956 by E.M. and G.R. Burbidge. The clear roadmap of primary nucleosynthesis advanced in 1954 by Hoyle describes the synthesis yielding the most abundant of the radioactive isotopes for astronomy, although that aspect was unrealized at the time. Secondary nucleosynthesis has also produced many observable radioactive nuclei, including the first gamma-ray-line emitter to be discovered in the galaxy and several others within stardust grains. Primary gamma-ray emitters would have been even more detectable in the early galaxy, when the birth rate of massive stars was greater; but secondary emitters, such as 26Al, would have been produced with smaller yield then owing to smaller abundance of seed nuclei from which to create them.

Primordial nucleosynthesis

International Nuclear Information System (INIS)

Gustavino, C.; Anders, M.; Bemmerer, D.; Elekes, Z.; Trezzi, D.

2016-01-01

Big Bang nucleosynthesis (BBN) describes the production of light nuclei in the early phases of the Universe. For this, precise knowledge of the cosmological parameters, such as the baryon density, as well as the cross section of the fusion reactions involved are needed. In general, the energies of interest for BBN are so low (E < 1 MeV) that nuclear cross section measurements are practically unfeasible at the Earth's surface. As of today, LUNA (Laboratory for Underground Nuclear Astrophysics) has been the only facility in the world available to perform direct measurements of small cross section in a very low background radiation. Owing to the background suppression provided by about 1400 meters of rock at the Laboratori Nazionali del Gran Sasso (LNGS), Italy, and to the high current offered by the LUNA accelerator, it has been possible to investigate cross sections at energies of interest for Big Bang nucleosynthesis using protons, 3 He and alpha particles as projectiles. The main reaction studied in the past at LUNA is the 2 H( 4 He, γ) 6 Li. Its cross section was measured directly, for the first time, in the BBN energy range. Other processes like 2 H(p, γ) 3 He, 3 He( 2 H, p) 4 He and 3 He( 4 He, γ) 7 Be were also studied at LUNA, thus enabling to reduce the uncertainty on the overall reaction rate and consequently on the determination of primordial abundances. The improvements on BBN due to the LUNA experimental data will be discussed and a perspective of future measurements will be outlined. (orig.)

Neutrino-Induced Nucleosynthesis in Helium Shells of Early Core-Collapse Supernovae

Directory of Open Access Journals (Sweden)

Banerjee Projjwal

2016-01-01

Full Text Available We summarize our studies on neutrino-driven nucleosynthesis in He shells of early core-collapse supernovae with metallicities of Z ≲ 10−3 Z⊙. We find that for progenitors of ∼ 11–15 M⊙, the neutrons released by 4He(ν¯ee, e+n3H in He shells can be captured to produce nuclei with mass numbers up to A ∼ 200. This mechanism is sensitive to neutrino emission spectra and flavor oscillations. In addition, we find two new primary mechanisms for neutrino-induced production of 9Be in He shells. The first mechanism produces 9Be via 7Li(n,γ8Li(n,γ9Li(e− ν¯ee9Be and relies on a low explosion energy for its survival. The second mechanism operates in progenitors of ∼ 8 M⊙, where 9Be can be produced directly via 7Li(3H, n09Be during the rapid expansion of the shocked Heshell material. The light nuclei 7Li and 3H involved in these mechanisms are produced by neutrino interactions with 4He. We discuss the implications of neutrino-induced nucleosynthesis in He shells for interpreting the elemental abundances in metal-poor stars.

Coherent Active-Sterile Neutrino Flavor Transformation in the Early Universe

Science.gov (United States)

Kishimoto, Chad T.; Fuller, George M.; Smith, Christel J.

2006-10-01

We solve the problem of coherent Mikheyev-Smirnov-Wolfenstein resonant active-to-sterile neutrino flavor conversion driven by an initial lepton number in the early Universe. We find incomplete destruction of the lepton number in this process and a sterile neutrino energy distribution with a distinctive cusp and high energy tail. These features imply alteration of the nonzero lepton number primordial nucleosynthesis paradigm when there exist sterile neutrinos with rest masses ms˜1eV. This could result in better light element probes of (constraints on) these particles.

Coherent Active-Sterile Neutrino Flavor Transformation in the Early Universe

International Nuclear Information System (INIS)

Kishimoto, Chad T.; Fuller, George M.; Smith, Christel J.

2006-01-01

We solve the problem of coherent Mikheyev-Smirnov-Wolfenstein resonant active-to-sterile neutrino flavor conversion driven by an initial lepton number in the early Universe. We find incomplete destruction of the lepton number in this process and a sterile neutrino energy distribution with a distinctive cusp and high energy tail. These features imply alteration of the nonzero lepton number primordial nucleosynthesis paradigm when there exist sterile neutrinos with rest masses m s ∼1 eV. This could result in better light element probes of (constraints on) these particles

Big-bang nucleosynthesis in the new cosmology

International Nuclear Information System (INIS)

Fields, B.D.

2005-01-01

Big bang nucleosynthesis (BBN) describes the production of the lightest elements in the first minutes of cosmic time. I will review the physics of cosmological element production, and the observations of the primordial element abundances. The comparison between theory and observation has heretofore provided our earliest probe of the universe, and given the best measure of the cosmic baryon content. However, BBN has now taken a new role in cosmology, in light of new precision measurements of the cosmic microwave background (CMB). Recent CMB anisotropy data yield a wealth of cosmological parameters; in particular, the baryon-to-photon ratio η = n B /n γ is measured to high precision. The confrontation between the BBN and CMB 'baryometers' poses a new and stringent test of the standard cosmology; the status of this test will be discussed. Moreover, it is now possible to recast the role of BBN by using the CMB to fix the baryon density and even some light element abundances. This strategy sharpens BBN into a more powerful probe of early universe physics, and of galactic nucleosynthesis processes. The impact of the CMB results on particle physics beyond the Standard Model, and on non-standard cosmology, will be illustrated. Prospects for improvement of these bounds via additional astronomical observations and nuclear experiments will be discussed, as will the lingering 'lithium problem.' (author)

Resonant Production of Sterile Neutrinos in the Early Universe

Science.gov (United States)

Gilbert, Lauren; Grohs, Evan; Fuller, George M.

2016-06-01

This study examines the cosmological impacts of a light resonantly produced sterile neutrino in the early universe. Such a neutrino could be produced through lepton number-driven Mikheyev-Smirnov-Wolfenstein (MSW) conversion of active neutrinos around big bang nucleosynthesis (BBN), resulting in a non-thermal spectrum of both sterile and electron neutrinos. During BBN, the neutron-proton ratio depends sensitively on the electron neutrino flux. If electron neutrinos are being converted to sterile neutrinos, this makes the n/p ratio a probe of possible new physics. We use observations of primordial Yp and D/H to place limits on this process.

Nucleosynthesis in Core-Collapse Supernovae

Science.gov (United States)

Stevenson, Taylor Shannon; Viktoria Ohstrom, Eva; Harris, James Austin; Hix, William R.

2018-01-01

The nucleosynthesis which occurs in core-collapse supernovae (CCSN) is one of the most important sources of elements in the universe. Elements from Oxygen through Iron come predominantly from supernovae, and contributions of heavier elements are also possible through processes like the weak r-process, the gamma process and the light element primary process. The composition of the ejecta depends on the mechanism of the explosion, thus simulations of high physical fidelity are needed to explore what elements and isotopes CCSN can contribute to Galactic Chemical Evolution. We will analyze the nucleosynthesis results from self-consistent CCSN simulations performed with CHIMERA, a multi-dimensional neutrino radiation-hydrodynamics code. Much of our understanding of CCSN nucleosynthesis comes from parameterized models, but unlike CHIMERA these fail to address essential physics, including turbulent flow/instability and neutrino-matter interaction. We will present nucleosynthesis predictions for the explosion of a 9.6 solar mass first generation star, relying both on results of the 160 species nuclear reaction network used in CHIMERA within this model and on post-processing with a more extensive network. The lowest mass iron core-collapse supernovae, like this model, are distinct from their more massive brethren, with their explosion mechanism and nucleosynthesis being more like electron capture supernovae resulting from Oxygen-Neon white dwarves. We will highlight the differences between the nucleosynthesis in this model and more massive supernovae. The inline 160 species network is a feature unique to CHIMERA, making this the most sophisticated model to date for a star of this type. We will discuss the need and mechanism to extrapolate the post-processing to times post-simulation and analyze the uncertainties this introduces for supernova nucleosynthesis. We will also compare the results from the inline 160 species network to the post-processing results to study further

Constraining axion dark matter with Big Bang Nucleosynthesis

Energy Technology Data Exchange (ETDEWEB)

Blum, Kfir; D' Agnolo, Raffaele Tito [Institute for Advanced Study, Princeton, NJ 08540 (United States); Lisanti, Mariangela; Safdi, Benjamin R. [Department of Physics, Princeton University, Princeton, NJ 08544 (United States)

2014-10-07

We show that Big Bang Nucleosynthesis (BBN) significantly constrains axion-like dark matter. The axion acts like an oscillating QCD θ angle that redshifts in the early Universe, increasing the neutron–proton mass difference at neutron freeze-out. An axion-like particle that couples too strongly to QCD results in the underproduction of {sup 4}He during BBN and is thus excluded. The BBN bound overlaps with much of the parameter space that would be covered by proposed searches for a time-varying neutron EDM. The QCD axion does not couple strongly enough to affect BBN.

Constraining axion dark matter with Big Bang Nucleosynthesis

Directory of Open Access Journals (Sweden)

Kfir Blum

2014-10-01

Full Text Available We show that Big Bang Nucleosynthesis (BBN significantly constrains axion-like dark matter. The axion acts like an oscillating QCD θ angle that redshifts in the early Universe, increasing the neutron–proton mass difference at neutron freeze-out. An axion-like particle that couples too strongly to QCD results in the underproduction of He4 during BBN and is thus excluded. The BBN bound overlaps with much of the parameter space that would be covered by proposed searches for a time-varying neutron EDM. The QCD axion does not couple strongly enough to affect BBN.

Baryonic density of the universe: Big Bang nucleosynthesis versus CMB observations

International Nuclear Information System (INIS)

Vangioni-Flam, E.; Coc, A.; Casse, M.

2003-01-01

Thanks to recent nuclear reaction rate compilations (NACRE[2]) and new experimental and theoretical works in nuclear physics, we have updated Standard Big Bang Nucleosynthesis (SBBN) calculations. The results are compared to the most representative light element abundances, measured in pristine astrophysical media to derive the baryonic density of the Universe. We confront Ω b h 2 obtained in this study with other values deduced from recent independent approaches as the observations of the anisotropies of the Cosmic Microwave Background (BOOMERANG, CBI, DASI, MAXIMA and VSA experiments) or the Lyman-α forest at high redshifts. Comparison between these results is a test of their consistency and could provide a better determination of this important cosmological parameter

Annihilation and gravitational clumping of monopoles in the early universe

International Nuclear Information System (INIS)

Izawa, Mizuo; Sato, Katsuhiko.

1983-01-01

In order to avoid the overproduction of magnetic monopoles in the early Universe, we investigate how monopoles evolve in the Big Bang Universe for arbitrary mass of monopoles and the arbitrary initial abundance. First, we calculate pair annihilation of monopoles by taking into account the entropy production due to the annihilations. Second, we investigate the formation of monopole stars and black holes due to gravitational clumping of monopoles. In particular, we take into account the entropy and baryon number generation by black hole evaporation. It is shown, however, that the burning of monopole stars or the evaporation of black holes cannot dilute the monopole abundance sufficiently without conflicts with present baryon/entropy ratio and primordial nucleosynthesis regardless of monopole mass. (author)

Hadronic decay of late-decaying particles and big-bang nucleosynthesis

Energy Technology Data Exchange (ETDEWEB)

Kawasaki, Masahiro [Research Center for the Early Universe, Graduate School of Science, University of Tokyo, Tokyo 113-0033 (Japan)]. E-mail: masahiro_kawasaki@mac.com; Kohri, Kazunori [Department of Earth and Space Science, Osaka University, Osaka 560-0043 (Japan); Moroi, Takeo [Department of Physics, Tohoku University, Sendai 980-8578 (Japan)

2005-10-06

We study the big-bang nucleosynthesis (BBN) scenario with late-decaying exotic particles with lifetime longer than {approx}1 s. With a late-decaying particle in the early universe, predictions of the standard BBN scenario can be significantly altered. Therefore, we derive constraints on its primordial abundance. We pay particular attention to hadronic decay modes of such particles. We see that the non-thermal production process of D, {sup 3}He and {sup 6}Li provides a stringent upper bound on the primordial abundance of late-decaying particles with hadronic branching ratio.

The primordial nucleosynthesis

International Nuclear Information System (INIS)

Audouze, J.

1984-01-01

This review of the primordial nucleosynthesis is divided in three chapters. In the first the author attempts to determine the primordial abundances of the lightest elements which can be formed by the Big Bang nucleosynthesis. The second is a summary of the Standard Big Bang nucleosynthesis. This simple and attractive model might be found in difficulty in the case of a primordial abundance of He <= 0.24 and/or in the case of models of galactic evolution allowing infall of external matter having a primordial composition. Finally, in the third, two alternative proposals to the Standard Big Bang nucleosynthesis are summarized. (Auth.)

Neutrino masses and mixings: Big Bang and Supernova nucleosynthesis and neutrino dark matter

International Nuclear Information System (INIS)

Fuller, George M.

1999-01-01

The existence of small mixings between light active and sterile neutrino species could have implications for Big Bang and Supernova Heavy Element Nucleosynthesis. As well, such mixing would force us to abandon cherished constraints on light neutrino Dark Matter. Two proposed 4-neutrino mass and mixing schemes, for example, can both accomodate existing experimental results and lead to elegant solutions to the neutron-deficit problem for r-Process nucleosynthesis from neutrino-heated supernova ejecta. Each of these solutions is based on matter-enhanced (MSW) active-sterile neutrino transformation. In plausible extensions of these schemes to the early universe, Shi and Fuller have shown that relatively light mass (∼200 eV to ∼10 keV) sterile neutrinos produced via active-sterile MSW conversion can have a ''cold'' energy spectrum. Neutrinos produced in this way circumvent the principal problem of light neutrino dark matter and would be, essentially, Cold Dark Matter

Primordial nucleosynthesis: A cosmological point of view

International Nuclear Information System (INIS)

Mathews, G. J.; Kajino, T.; Yamazaki, D.; Kusakabe, M.; Cheoun, M.-K.

2014-01-01

Primordial nucleosynthesis remains as one of the pillars of modern cosmology. It is the test-ing ground upon which all cosmological models must ultimately rest. It is our only probe of the universe during the first few minutes of cosmic expansion and in particular during the important radiation-dominated epoch. These lectures review the basic equations of space-time, cosmology, and big bang nucleosynthesis. We will then review the current state of observational constraints on primordial abundances along with the key nuclear reactions and their uncertainties. We summarize which nuclear measure-ments are most crucial during the big bang. We also review various cosmological models and their constraints. In particular, we summarize 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

Trojan Horse cross section measurements and their impact on primordial nucleosynthesis

Science.gov (United States)

Pizzone, R. G.; Spartá, R.; Bertulani, C.; Spitaleri, C.; La Cognata, M.; Lamia, L.; Mukhamedzhanov, A.; Tumino, A.

2018-01-01

Big Bang Nucleosynthesis (BBN) nucleosynthesis requires several nuclear physics inputs and, among them, an important role is played by nuclear reaction rates. They are among the most important input for a quantitative description of the early Universe. An up-to-date compilation of direct cross sections of d(d,p)t, d(d,n)3He and 3He(d,p)4He reactions is given, being these ones among the most uncertain bare-nucleus cross sections. An intense experimental effort has been carried on in the last decade to apply the Trojan Horse Method (THM) to study reactions of relevance for the BBN and measure their astrophysical S(E)-factor. The result of these recent measurements is reviewed and compared with the available direct data. The reaction rates and the relative error for the four reactions of interest are then numerically calculated in the temperature ranges of relevance for BBN (0.01nucleosynthesis calculations in order to evaluate their impact on the calculated primordial abundances of D, 3,4He and 7Li. These ones were then compared with the observational primordial abundance estimates in different astrophysical sites. A comparison was also performed with calculations using other reaction rates compilations available in literature.

Big-bang nucleosynthesis - observational aspects

International Nuclear Information System (INIS)

Pagel, B.E.J.

1990-01-01

Extrapolation of observational data on the abundances of D, 3 He, 4 He and 7 Li in various astrophysical objects to derive their primordial values leads to results in good accordance with calculations from Standard Big Bang nucleosynthesis theory over 9 orders of magnitude in abundance and has led to the following predictions: There are not more than 3 light neutrino species or other particles contributing relativistic degrees of freedom at temperatures of a few MeV; the neutron half-life is less than 10.4 minutes; and baryonic dark matter exists, but not in sufficient quantities to close the universe. (The first two of these predictions have been confirmed by laboratory experiments). Searches for a primordial component in the abundance of any other element heavier than hydrogen - such as might have resulted from inhomogeneities due to phase transitions in the early universe, notably the quark-hadron transition - have so far proved completely negative. The primordial helium abundance is found from observations of extragalactic ionized hydrogen clouds to be close to 0.230 by mass, a little lower than predicted, but the difference does not exceed likely errors. (orig.)

Introduction to big bang nucleosynthesis and modern cosmology

Science.gov (United States)

Mathews, Grant J.; Kusakabe, Motohiko; Kajino, Toshitaka

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.

Testing the Friedmann equation: The expansion of the universe during big-bang nucleosynthesis

International Nuclear Information System (INIS)

Carroll, Sean M.; Kaplinghat, Manoj

2002-01-01

In conventional general relativity, the expansion rate H of a Robertson-Walker universe is related to the energy density by the Friedmann equation. Aside from the present day, the only epoch at which we can constrain the expansion history in a model-independent way is during big-bang nucleosynthesis (BBN). We consider a simple two-parameter characterization of the behavior of H during BBN and derive constraints on this parameter space, finding that the allowed region of parameter space is essentially one dimensional. We also study the effects of a large neutrino asymmetry within this framework. Our results provide a simple way to compare an alternative cosmology to the observational requirement of matching the primordial abundances of the light elements

Introduction to nucleosynthesis

International Nuclear Information System (INIS)

Guasp, J.

1975-01-01

After a short introduction on stellar evolution, the physical foundations of nucleosynthesis are exposed: H, He, C and O fusion, Si burning and the equilibrium process. The effect of neutrinos in the last stages of stellar evolution and Supernova explosions are treated too. Afterwards the neutron capture process, fast and slow, are considerated concluding with cosmic nucleogenesis and nucleosynthesis in overmasive objects. (author)

Constraints on lifetime and mass of heavy lepton neutrinos imposed by big bang nucleosynthesis

International Nuclear Information System (INIS)

Miyama, Shoken; Sato, Katsuhiko

1978-01-01

If there exist massive neutral leptons (heavy neutrinos), they would have been produced in thermal equilibrium in the early stages of the universe. The effects of their presence and decay on the big bang nucleosynthesis are investigated in detail and abundances of the products 4 He, 2 H and 7 Li are compared with the observed cosmic abundances. We have determined a region in the lifetime-mass diagram of the heavy neutrino which should be ruled out in order for the big bang nucleosynthesis not to conflict with observed abundances of the elements. In addition, if a lower limit of the lifetime obtained from the Weinberg-Salam type theory, tau>=6 x 10 7 (1 MeV/m sub(νh)) 5 sec, is assumed, where m sub(νh) is the mass of the heavy neutrino, the mass range of 70 eV< m sub(νh)<10 MeV is ruled out. The other constraints on the mass and the lifetime obtained from astrophysical considerations are also discussed and summarized. (author)

Big Bang nucleosynthesis: Accelerator tests and can Ω/sub B/ really be large

International Nuclear Information System (INIS)

Schramm, D.N.

1987-10-01

The first collider tests of cosmological theory are now underway. The number of neutrino families in nature, N/sub nu/, plays a key role in elementary particle physics as well as in the synthesis of the light elements during the early evolution of the Universe. Standard Big Bang Nucleosynthesis argues for N/sub nu/ = 3 +- 1. Current limits on N/sub nu/ from the CERN anti pp collider and e + e - colliders are presented and compared to the cosmological bound. Supernova SN 1987A is also shown to give a limit on N/sub nu/ comparable to current accelerator bounds. All numbers are found to be small thus verifying the Big Bang model at an earlier epoch than is possible by traditional astronomical observations. Future measurements at SLC and LEP will further tighten this argument. Another key prediction of the standard Big Bang Nucleosynthesis is that the baryon density must be small (Ω/sub B/ ≤ 0.1). Recent attempts to try to subvert this argument using homogeneities of various types are shown to run afoul of the 7 Li abundance which has now become a rather firm constraint. 18 refs., 2 figs

Massive black holes and light-element nucleosynthesis in a baryonic universe

Science.gov (United States)

Gnedin, Nickolay Y.; Ostriker, Jeremiah P.; Rees, Martin J.

1995-01-01

We reexamine the model proposed by Gnedin & Ostriker (1992) in which Jeans mass black holes (M(sub BH) approximately = 10(exp 6) solar mass) form shortly after decoupling. There is no nonbaryonic dark matter in this model, but we examine the possibility that Omega(sub b) is considerably larger than given by normal nucleosynthesis. Here we allow for the fact that much of the high baryon-to-photon ratio material will collapse leaving the universe of remaining material with light-element abundances more in accord with the residual baryonic density (approximately = 10(exp -2)) than with Omega(sub 0) and the initial baryonic density (approximately = 10(exp -1)). We find that no reasonable model can be made with random-phase density fluctuations, if the power on scales smaller than 10(exp 6) solar mass is as large as expected. However, phase-correlated models of the type that might occur in connection with topological singularities can be made with Omega(sub b) h(exp 2) = 0.013 +/- 0.001, 0.15 approximately less than Omega(sub 0) approximately less than 0.4, which are either flat (Omega(sub lambda) = 1 - Omega(sub 0)) or open (Omega(sub lambda) = 0) and which satisfy all the observational constraints which we apply, including the large baryon-to-total mass ratio found in the X-ray clusters. The remnant baryon density is thus close to that obtained in the standard picture (Omega(sub b) h(exp 2) = 0.0125 +/- 0.0025; Walker et al. 1991). The spectral index implied for fluctuations in the baryonic isocurvature scenario, -1 less than m less than 0, is in the range expected by other arguments based on large-scale structure and microwave fluctuation constraints. The dark matter in this picture is in the form of massive black holes. Accretion onto them at early epochs releases high-energy photons which significantly heat and reionize the universe. But photodissociation does not materially change light-element abundances. A typical model gives bar-y approximately = 1 x 10(exp -5

Big bang nucleosynthesis

International Nuclear Information System (INIS)

Boyd, Richard N.

2001-01-01

The precision of measurements in modern cosmology has made huge strides in recent years, with measurements of the cosmic microwave background and the determination of the Hubble constant now rivaling the level of precision of the predictions of big bang nucleosynthesis. However, these results are not necessarily consistent with the predictions of the Standard Model of big bang nucleosynthesis. Reconciling these discrepancies may require extensions of the basic tenets of the model, and possibly of the reaction rates that determine the big bang abundances

Experimental approach to explosive nucleosynthesis

International Nuclear Information System (INIS)

Kubono, S.

1991-07-01

Recent development of experimental studies on explosive nucleosynthesis, especially the rapid proton process and the primordial nucleosynthesis were discussed with a stress on unstable nuclei. New development in the experimental methods for the nuclear astrophysics is also discussed which use unstable nuclear beams. (author)

Chemical Evolution and the Formation of Dwarf Galaxies in the Early Universe

Science.gov (United States)

Cote, Benoit; JINA-CEE, NuGrid, ChETEC

2018-06-01

Stellar abundances in local dwarf galaxies offer a unique window into the nature and nucleosynthesis of the first stars. They also contain clues regarding how galaxies formed and assembled in the early stages of the universe. In this talk, I will present our effort to connect nuclear astrophysics with the field of galaxy formation in order to define what can be learned about galaxy evolution using stellar abundances. In particular, I will describe the current state of our numerical chemical evolution pipeline which accounts for the mass assembly history of galaxies, present how we use high-redshift cosmological hydrodynamic simulations to calibrate our models and to learn about the formation of dwarf galaxies, and address the challenge of identifying the dominant r-process site(s) using stellar abundances.

Sun's dynamics and nucleosynthesis

International Nuclear Information System (INIS)

Gavanescu, Adela; Rusu, Mircea V.

2005-01-01

Nucleosynthesis processes in the sun are one of the main results related to the evolution of the Sun. Dynamics and energetics of the Sun could be studied indirectly by their elements products in produced by nucleosynthesis. Also solar atmosphere and its characteristics reveled in its full development is observed during the solar eclipses. We try to correlate these facts in order to obtained data to be used in solar models. (authors)

Explosive processes in nucleosynthesis

International Nuclear Information System (INIS)

Boyd, R.N.

2002-01-01

There are many explosive processes in nucleosynthesis: big bang nucleosynthesis, the rp-process, the γ-process, the ν-process, and the r-process. However, I will discuss just the rp-process and the r-process in detail, primarily because both seem to have been very active research areas of late, and because they have great potential for studies with radioactive nuclear beams. I will also discuss briefly the γ-process because of its inevitability in conjunction with the rp-process. (orig.)

The first three minutes - 1990 version. [of early universe after Big Bang

Science.gov (United States)

Schramm, David N.

1991-01-01

The present state of understanding of what occurred in the universe's first three minutes is reviewed. Emphasis is on the events that lead to potentially observable consequences and that are model-independent or at least generic to broad classes of models. Inflation, phase transitions, dark matter, and nucleosynthesis are summarized.

Dark/visible parallel universes and Big Bang nucleosynthesis

International Nuclear Information System (INIS)

Bertulani, C. A.; Frederico, T.; Fuqua, J.; Hussein, M. S.; Oliveira, O.; Paula, W. de

2012-01-01

We develop a model for visible matter-dark matter interaction based on the exchange of a massive gray boson called herein the Mulato. Our model hinges on the assumption that all known particles in the visible matter have their counterparts in the dark matter. We postulate six families of particles five of which are dark. This leads to the unavoidable postulation of six parallel worlds, the visible one and five invisible worlds. A close study of big bang nucleosynthesis (BBN), baryon asymmetries, cosmic microwave background (CMB) bounds, galaxy dynamics, together with the Standard Model assumptions, help us to set a limit on the mass and width of the new gauge boson. Modification of the statistics underlying the kinetic energy distribution of particles during the BBN is also discussed. The changes in reaction rates during the BBN due to a departure from the Debye-Hueckel electron screening model is also investigated.

Nucleosynthesis in Supernovae

Science.gov (United States)

Thielemann, Friedrich-Karl; Isern, Jordi; Perego, Albino; von Ballmoos, Peter

2018-04-01

We present the status and open problems of nucleosynthesis in supernova explosions of both types, responsible for the production of the intermediate mass, Fe-group and heavier elements (with the exception of the main s-process). Constraints from observations can be provided through individual supernovae (SNe) or their remnants (e.g. via spectra and gamma-rays of decaying unstable isotopes) and through surface abundances of stars which witness the composition of the interstellar gas at their formation. With a changing fraction of elements heavier than He in these stars (known as metallicity) the evolution of the nucleosynthesis in galaxies over time can be determined. A complementary way, related to gamma-rays from radioactive decays, is the observation of positrons released in β+-decays, as e.g. from ^{26}Al, ^{44}Ti, ^{56,57}Ni and possibly further isotopes of their decay chains (in competition with the production of e+e- pairs in acceleration shocks from SN remnants, pulsars, magnetars or even of particle physics origin). We discuss (a) the role of the core-collapse supernova explosion mechanism for the composition of intermediate mass, Fe-group (and heavier?) ejecta, (b) the transition from neutron stars to black holes as the final result of the collapse of massive stars, and the relation of the latter to supernovae, faint supernovae, and gamma-ray bursts/hypernovae, (c) Type Ia supernovae and their nucleosynthesis (e.g. addressing the ^{55}Mn puzzle), plus (d) further constraints from galactic evolution, γ-ray and positron observations. This is complemented by the role of rare magneto-rotational supernovae (related to magnetars) in comparison with the nucleosynthesis of compact binary mergers, especially with respect to forming the heaviest r-process elements in galactic evolution.

Superweakly interacting massive particle dark matter signals from the early Universe

International Nuclear Information System (INIS)

Feng, Jonathan L.; Rajaraman, Arvind; Takayama, Fumihiro

2003-01-01

Cold dark matter may be made of superweakly interacting massive particles, super-WIMP's, that naturally inherit the desired relic density from late decays of metastable WIMP's. Well-motivated examples are weak-scale gravitinos in supergravity and Kaluza-Klein gravitons from extra dimensions. These particles are impossible to detect in all dark matter experiments. We find, however, that super-WIMP dark matter may be discovered through cosmological signatures from the early Universe. In particular, super-WIMP dark matter has observable consequences for big bang nucleosynthesis and the cosmic microwave background (CMB), and may explain the observed underabundance of 7 Li without upsetting the concordance between deuterium and CMB baryometers. We discuss the implications for future probes of CMB blackbody distortions and collider searches for new particles. In the course of this study, we also present a model-independent analysis of entropy production from late-decaying particles in light of Wilkinson microwave anisotropy probe data

Constraining nuclear data via cosmological observations: Neutrino energy transport and big bang nucleosynthesis

Directory of Open Access Journals (Sweden)

Paris Mark

2017-01-01

Full Text Available We introduce a new computational capability that moves toward a self-consistent calculation of neutrino transport and nuclear reactions for big bang nucleosynthesis (BBN. Such a self-consistent approach is needed to be able to extract detailed information about nuclear reactions and physics beyond the standard model from precision cosmological observations of primordial nuclides and the cosmic microwave background radiation. We calculate the evolution of the early universe through the epochs of weak decoupling, weak freeze-out and big bang nucleosynthesis (BBN by simultaneously coupling a full strong, electromagnetic, and weak nuclear reaction network with a multi-energy group Boltzmann neutrino energy transport scheme. The modular structure of our approach allows the dissection of the relative contributions of each process responsible for evolving the dynamics of the early universe. Such an approach allows a detailed account of the evolution of the active neutrino energy distribution functions alongside and self-consistently with the nuclear reactions and entropy/heat generation and 'ow between the neutrino and photon/electron/positron/baryon plasma components. Our calculations reveal nonlinear feedback in the time evolution of neutrino distribution functions and plasma thermodynamic conditions. We discuss the time development of neutrino spectral distortions and concomitant entropy production and extraction from the plasma. These e↑ects result in changes in the computed values of the BBN deuterium and helium-4 yields that are on the order of a half-percent relative to a baseline standard BBN calculation with no neutrino transport. This is an order of magnitude larger e↑ect than in previous estimates. For particular implementations of quantum corrections in plasma thermodynamics, our calculations show a 0.4% increase in deuterium and a 0.6% decrease in 4He over our baseline. The magnitude of these changes are on the order of uncertainties

Convergence of scalar-tensor theories towards general relativity and primordial nucleosynthesis

International Nuclear Information System (INIS)

Serna, A; Alimi, J-M; Navarro, A

2002-01-01

In this paper, we analyse the conditions for convergence towards general relativity of scalar-tensor gravity theories defined by an arbitrary coupling function α (in the Einstein frame). We show that, in general, the evolution of the scalar field (φ) is governed by two opposite mechanisms: an attraction mechanism which tends to drive scalar-tensor models towards Einstein's theory, and a repulsion mechanism which has the contrary effect. The attraction mechanism dominates the recent epochs of the universe evolution if, and only if, the scalar field and its derivative satisfy certain boundary conditions. Since these conditions for convergence towards general relativity depend on the particular scalar-tensor theory used to describe the universe evolution, the nucleosynthesis bounds on the present value of the coupling function, α 0 , strongly differ from some theories to others. For example, in theories defined by α ∝ |φ| analytical estimates lead to very stringent nucleosynthesis bounds on α 0 (∼ -19 ). By contrast, in scalar-tensor theories defined by α ∝ φ much larger limits on α 0 (∼ -7 ) are found

Nucleosynthesis outreach slides

Energy Technology Data Exchange (ETDEWEB)

Lippuner, Jonas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-11-03

The purpose of this report is to explain s- and r-process nucleosynthesis to the general public at outreach events, specifically in a Planetarium show at the Pajarito Environmental Education Center in Los Alamos.

Cosmology of a charged universe

International Nuclear Information System (INIS)

Barnes, A.

1979-01-01

The Proca generalization of electrodynamics admits the possibility that the universe could possess a net electric charge uniformly distributed throughout space, while possessing no electric field. A charged intergalactic (and intragalactic) medium of this kind could contain enough energy to be of cosmological importance. A general-relativistic model of cosmological expansion dominated by such a charged background has been calculated, and is consistent with present observational limits on the Hubble constant, the decleration parameter, and the age of the universe. However, if this cosmology applied at the present epoch, the very early expansion of the universe would have been much more rapid than in conventional ''big bang'' cosmologies, too rapid for cosmological nucleosynthesis or thermalization of the background radiation to have occurred. Hence, domination of the present expansion by background charge appears to be incompatible with the 3 K background and big-bang production of light elements. If the present background charge density were sufficiently small (but not strictly zero), expansion from the epoch of nucleosynthesis would proceed according to the conventional scenario, but the energy due to the background charge would have dominated at some earlier epoch. This last possibility leads to equality of pressure and energy density in the primordial universe, a condition of special significance in certain cosmological theories

Nucleosynthesis Constraints on a Massive Gravitino in Neutralino Dark Matter Scenarios

CERN Document Server

Cyburt, Richard H; Fields, Brian D; Luo, Feng; Olive, Keith A; Spanos, Vassilis C

2009-01-01

The decays of massive gravitinos into neutralino dark matter particles and Standard Model secondaries during or after Big-Bang nucleosynthesis (BBN) may alter the primordial light-element abundances. We present here details of a new suite of codes for evaluating such effects, including a new treatment based on PYTHIA of the evolution of showers induced by hadronic decays of massive, unstable particles such as a gravitino. We also develop an analytical treatment of non-thermal hadron propagation in the early universe, and use this to derive analytical estimates for light-element production and in turn on decaying particle lifetimes and abundances. We then consider specifically the case of an unstable massive gravitino within the constrained minimal supersymmetric extension of the Standard Model (CMSSM). We present upper limits on its possible primordial abundance before decay for different possible gravitino masses, with CMSSM parameters along strips where the lightest neutralino provides all the astrophysical...

Convergence of scalar-tensor theories towards general relativity and primordial nucleosynthesis

Energy Technology Data Exchange (ETDEWEB)

Serna, A [Dept. Fisica y Computacion, Universidad Miguel Hernandez, E03202-Elche (Spain); Alimi, J-M [LAEC, CNRS-UMR 8631, Observatoire de Paris-Meudon, F92195-Meudon (France); Navarro, A [Dept. Fisica, Universidad de Murcia, E30071-Murcia (Spain)

2002-03-07

In this paper, we analyse the conditions for convergence towards general relativity of scalar-tensor gravity theories defined by an arbitrary coupling function {alpha} (in the Einstein frame). We show that, in general, the evolution of the scalar field ({phi}) is governed by two opposite mechanisms: an attraction mechanism which tends to drive scalar-tensor models towards Einstein's theory, and a repulsion mechanism which has the contrary effect. The attraction mechanism dominates the recent epochs of the universe evolution if, and only if, the scalar field and its derivative satisfy certain boundary conditions. Since these conditions for convergence towards general relativity depend on the particular scalar-tensor theory used to describe the universe evolution, the nucleosynthesis bounds on the present value of the coupling function, {alpha}{sub 0}, strongly differ from some theories to others. For example, in theories defined by {alpha} {proportional_to} |{phi}| analytical estimates lead to very stringent nucleosynthesis bounds on {alpha}{sub 0}({approx}<10{sup -19}). By contrast, in scalar-tensor theories defined by {alpha} {proportional_to} {phi} much larger limits on {alpha}{sub 0}({approx}<10{sup -7}) are found.

Stellar Archaeology -- Exploring the Universe with Metal-Poor Stars

OpenAIRE

Frebel, Anna

2010-01-01

The abundance patterns of the most metal-poor stars in the Galactic halo and small dwarf galaxies provide us with a wealth of information about the early Universe. In particular, these old survivors allow us to study the nature of the first stars and supernovae, the relevant nucleosynthesis processes responsible for the formation and evolution of the elements, early star- and galaxy formation processes, as well as the assembly process of the stellar halo from dwarf galaxies a long time ago. T...

Constraining pre big-bang-nucleosynthesis expansion using cosmic antiprotons

Energy Technology Data Exchange (ETDEWEB)

Schelke, M. [Istituto Nazionale di Fisica Nucleare, Torino (Italy); Catena, R. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Fornengo, N. [Torino Univ. (Italy). Dipt. di Fisica Teorica]|[Istituto Nazionale di Fisica Nucleare, Torino (Italy); Masiero, A. [Pavoa Univ. (Italy). Dipt. di Fisica]|[Istituto Nazionale di Fisica Nucleare, Padova (Italy); Pietroni, M. [Istituto Nazionale di Fisica Nucleare, Padova (Italy)

2006-06-15

A host of dark energy models and non-standard cosmologies predict an enhanced Hubble rate in the early Universe: perfectly viable models, which satisfy Big Bang Nucleosynthesis (BBN), cosmic microwave background and general relativity tests, may nevertheless lead to enhancements of the Hubble rate up to many orders of magnitude. In this paper we show that strong bounds on the pre-BBN evolution of the Universe may be derived, under the assumption that dark matter is a thermal relic, by combining the dark matter relic density bound with constraints coming from the production of cosmic-ray antiprotons by dark matter annihilation in the Galaxy. The limits we derive can be sizable and apply to the Hubble rate around the temperature of dark matter decoupling. For dark matter masses lighter than 100 GeV, the bound on the Hubble-rate enhancement ranges from a factor of a few to a factor of 30, depending on the actual cosmological model, while for a mass of 500 GeV the bound falls in the range 50-500. Uncertainties in the derivation of the bounds and situations where the bounds become looser are discussed. We finally discuss how these limits apply to some specific realizations of non-standard cosmologies: a scalar-tensor gravity model, kination models and a Randall-Sundrum D-brane model. (Orig.)

Constraining pre big-bang-nucleosynthesis expansion using cosmic antiprotons

International Nuclear Information System (INIS)

Schelke, M.; Catena, R.; Fornengo, N.; Masiero, A.; Pietroni, M.

2006-06-01

A host of dark energy models and non-standard cosmologies predict an enhanced Hubble rate in the early Universe: perfectly viable models, which satisfy Big Bang Nucleosynthesis (BBN), cosmic microwave background and general relativity tests, may nevertheless lead to enhancements of the Hubble rate up to many orders of magnitude. In this paper we show that strong bounds on the pre-BBN evolution of the Universe may be derived, under the assumption that dark matter is a thermal relic, by combining the dark matter relic density bound with constraints coming from the production of cosmic-ray antiprotons by dark matter annihilation in the Galaxy. The limits we derive can be sizable and apply to the Hubble rate around the temperature of dark matter decoupling. For dark matter masses lighter than 100 GeV, the bound on the Hubble-rate enhancement ranges from a factor of a few to a factor of 30, depending on the actual cosmological model, while for a mass of 500 GeV the bound falls in the range 50-500. Uncertainties in the derivation of the bounds and situations where the bounds become looser are discussed. We finally discuss how these limits apply to some specific realizations of non-standard cosmologies: a scalar-tensor gravity model, kination models and a Randall-Sundrum D-brane model. (Orig.)

Testing a Dilaton Gravity Model Using Nucleosynthesis

International Nuclear Information System (INIS)

Boran, S.; Kahya, E. O.

2014-01-01

Big bang nucleosynthesis (BBN) offers one of the most strict evidences for the Λ-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, 3 He, 4 He, T, and 7 Li) are significantly different for some cases, and a comparison is given between a particular dilaton gravity model and Λ-CDM in the light of the astrophysical observations

Big bang nucleosynthesis - Predictions and uncertainties

International Nuclear Information System (INIS)

Krauss, L.M.; Romanelli, P.

1990-01-01

A detailed reexamination is made of primordial big-bang nucleosynthesis (BBN), concentrating on the data for the main nuclear reactions leading to the production of Li-7, He-3 and D, and on the neutron half-life, relevant for He-4 production. The new values for reaction rates and uncertainties are then used as input in a Monte Carlo analysis of big bang nucleosynthesis of light elements. This allows confidence levels for the predictions of the standard BBN model to be high. 70 refs

Big Bang nucleosynthesis and abundances of light elements

International Nuclear Information System (INIS)

Pagel, B.E.J.

1991-01-01

Big Bang nucleosynthesis (BBNS) theory is sketched, indicating the dependence of primordial abundances of D, 3 He, 4 He and 7 Li on the mean baryonic density of the universe and the dependence of 4 He on the number of neutrino families and the neutron half-life. Observational data and inferred primordial abundances of these elements are reviewed and shown to be consistent (within errors) either with standard BBNS in a homogeneous universe about 100 seconds after the Big Bang or with moderately inhomogeneous BBNS models resulting from earlier phase transitions like the quark-hadron transition if this is first order. However, models with closure density supplied by baryons are apparently ruled out. Finally, implications for the existence of baryonic and non-baryonic dark matter are briefly discussed. (orig.)

Dirac cosmology and the onset of galactic nucleosynthesis

International Nuclear Information System (INIS)

Adams, P.J.; Canuto, V.

1976-01-01

Recently Browne and Berman determined the onset of nucleosynthesis of heavy elements in the galaxy to be about 18 billion years ago based on the weak decay of rhenium 187 to osmium 187. This age is appreciably larger than the 13 billion years determined from the uranium decay chains. It is also larger than the 16 billion year age of the Universe determined from the standard model by the latest values of the Hubble constant and deceleration parameter. This letter points out that this discrepancy is predicted by Dirac's cosmology and derives from a time-varying weak coupling constant. (Auth.)

Primordial nucleosynthesis in the new cosmology

International Nuclear Information System (INIS)

Cyburt, R.H.

2003-01-01

Big bang nucleosynthesis (BBN) and the cosmic microwave background (CMB) anisotropies independently predict the universal baryon density. Comparing their predictions will provide a fundamental test on cosmology. Using BBN and the CMB together, we will be able to constrain particle physics, and predict the primordial, light element abundances. These future analyses hinge on new experimental and observational data. New experimental data on nuclear cross sections will help reduce theoretical uncertainties in BBN's predictions. New observations of light element abundances will further sharpen BBN's probe of the baryon density. Observations from the MAP and PLANCK satellites will measure the fluctuations in the CMB to unprecedented accuracy, allowing the precise determination of the baryon density. When combined, this data will present us with the opportunity to perform precision cosmology

Post-recombination early Universe cooling by translation-internal inter-conversion: The role of minor constituents.

Science.gov (United States)

McCaffery, Anthony J

2015-09-14

Little is known of the mechanism by which H and H2, the principal constituents of the post-re-combination early Universe, cooled sufficiently to permit cluster formation, nucleosynthesis, and, eventually, the formation of structured objects. Radiative decay primarily cools the internal modes of H2, as Δj = - 2 jumps accompany quadrupolar emission. This, however, would be a self-limiting mechanism. In this work, a translational energy cooling mechanism based on collision-induced, translation-to-internal mode conversion, is extended, following an earlier study [A. J. McCaffery and R. J. Marsh, J. Chem. Phys. 139, 234310 (2013)] of ensembles comprising H2 in a H atom bath gas. Here, the possible influence of minor species, such as HD, on this cooling mechanism is investigated. Results suggest that the influence of HD is small but not insignificant. Conversion is very rapid and an overall translation-to-internal energy conversion efficiency of some 5% could be expected. This finding may be of use in the further development of models of this complex phase of early Universe evolution. An unexpected finding in this study was that H2 + HD ensembles are capable of very rapid translation-to-internal conversion with efficiencies of >40% and relaxation rates that appear to be relatively slow. This may have potential as an energy storage mechanism.

Nucleosynthesis in cold white dwarf explosions

International Nuclear Information System (INIS)

Canal, R.; Hernanz, M.

1986-01-01

Type I supernovae (SNI) are generally thought to be the main contributors to the galactic nucleosynthesis of iron-peak elements and their yields of intermediate-mass elements may also be important. We concentrate here upon a different class of models, based on the explosion of cold, massive, partially solid white dwarfs. We show that such white dwarfs must be relatively frequent among SNI progenitors and how their hydrodynamics upon ignition is very different from that of hotter, fluid white dwarfs. The implications for nucleosynthesis are briefly discussed and some preliminary results are presented

Explosive Nucleosynthesis in Different Ye Conditions

International Nuclear Information System (INIS)

Iwamoto, Nobuyuki; Umeda, Hideyuki; Nomoto, Ken'ichi; Tominaga, Nozomu; Thielemann, Friedrich-Karl; Hix, W. Raphael

2006-01-01

The influence of a large variation of Ye on explosive yield is investigated. We calculate nucleosynthesis with the initial electron fraction Ye ranging from 0.48 to 0.58 in explosive Si burning region in Population III, 25 M· supernovae. We obtain the significant overproduction of odd elements, K and Sc. In the Ye < 0.5 cases light p-process nuclei are enhanced. We find that the abundance pattern taken from arbitrary mixture of each nucleosynthesis yield in various values of Ye can reasonably explain that in observed extremely metal-poor stars

Primordial nucleosynthesis.

Science.gov (United States)

Schramm, D N

1998-01-06

With the advent of the new extragalactic deuterium observations, Big Bang nucleosynthesis (BBN) is on the verge of undergoing a transformation. In the past, the emphasis has been on demonstrating the concordance of the BBN model with the abundances of the light isotopes extrapolated back to their primordial values by using stellar and galactic evolution theories. As a direct measure of primordial deuterium 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. This robustness remains even through major model variations such as an assumed first-order quark-hadron phase transition. 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 nonbaryonic. Comparison of baryonic density arguments from Lyman-alpha clouds, x-ray gas in clusters, and the microwave anisotropy are made.

Nucleosynthesis and the nova outburst

International Nuclear Information System (INIS)

Starrfield, S.

1995-01-01

A nova outburst is the consequence of the accretion of hydrogen rich material onto a white dwarf and it can be considered as the largest hydrogen bomb in the Universe. The fuel is supplied by a secondary star in a close binary system while the strong degeneracy of the massive white dwarf acts to contain the gas during the early stages of the explosion. The containment allows the temperature in the nuclear burning region to exceed 10 8 K under all circumstances. As a result a major fraction of CNO nuclei in the envelope are transformed into β + -unstable nuclei. We discuss the effects of these nuclei on the evolution. Recent observational studies have shown that there are two compositional classes of novae; one which occurs on carbon-oxygen white dwarfs, and a second class that occurs on oxygen-neon-magnesium white dwarfs. In this review we will concentrate on the latter explosions since they produce the most interesting nucleosynthesis. We report both on the results of new observational determinations of nova abundances and, in addition, new hydrodynamic calculations that examine the consequences of the accretion process on 1.0M circle-dot , 1.25M circle-dot , and 1.35M circle-dot white dwarfs. Our results show that novae can produce 22 Na, 26 Al, and other intermediate mass nuclei in interesting amounts. We will present the results of new calculations, done with updated nuclear reaction rates and opacities, which exhibit quantitative differences with respect to published work

Nucleosynthesis in stellar explosions

International Nuclear Information System (INIS)

Woosley, S.E.; Axelrod, T.S.; Weaver, T.A.

1983-01-01

The final evolution and explosion of stars from 10 M/sub solar/ to 10 6 M/sub solar/ are reviewed with emphasis on factors affecting the expected nucleosynthesis. We order our paper in a sequence of decreasing mass. If, as many suspect, the stellar birth function was peaked towards larger masses at earlier times (see e.g., Silk 1977; but also see Palla, Salpeter, and Stahler 1983), this sequence of masses might also be regarded as a temporal sequence. At each stage of Galactic chemical evolution stars form from the ashes of preceding generations which typically had greater mass. A wide variety of Type I supernova models, most based upon accreting white dwarf stars, are also explored using the expected light curves, spectra, and nucleosynthesis as diagnostics. No clearly favored Type I model emerges that is capable of simultaneously satisfying all three constraints

Big-bang nucleosynthesis and the baryon density of the universe.

Science.gov (United States)

Copi, C J; Schramm, D N; Turner, M S

1995-01-13

For almost 30 years, the predictions of big-bang nucleosynthesis have been used to test the big-bang model to within a fraction of a second of the bang. The agreement between the predicted and observed abundances of deuterium, helium-3, helium-4, and lithium-7 confirms the standard cosmology model and allows accurate determination of the baryon density, between 1.7 x 10(-31) and 4.1 x 10(-31) grams per cubic centimeter (corresponding to about 1 to 15 percent of the critical density). This measurement of the density of ordinary matter is pivotal to the establishment of two dark-matter problems: (i) most of the baryons are dark, and (ii) if the total mass density is greater than about 15 percent of the critical density, as many determinations indicate, the bulk of the dark matter must be "non-baryonic," composed of elementary particles left from the earliest moments.

Nucleosynthesis in stellar explosions

Energy Technology Data Exchange (ETDEWEB)

Woosley, S.E.; Axelrod, T.S.; Weaver, T.A.

1983-01-01

The final evolution and explosion of stars from 10 M/sub solar/ to 10/sup 6/ M/sub solar/ are reviewed with emphasis on factors affecting the expected nucleosynthesis. We order our paper in a sequence of decreasing mass. If, as many suspect, the stellar birth function was peaked towards larger masses at earlier times (see e.g., Silk 1977; but also see Palla, Salpeter, and Stahler 1983), this sequence of masses might also be regarded as a temporal sequence. At each stage of Galactic chemical evolution stars form from the ashes of preceding generations which typically had greater mass. A wide variety of Type I supernova models, most based upon accreting white dwarf stars, are also explored using the expected light curves, spectra, and nucleosynthesis as diagnostics. No clearly favored Type I model emerges that is capable of simultaneously satisfying all three constraints.

Dynamical 3-Space Predicts Hotter Early Universe: Resolves CMB-BBN 7-Li and 4-He Abundance Anomalies

Directory of Open Access Journals (Sweden)

Cahill R. T.

2010-01-01

Full Text Available The observed abundances of 7-Li and 4-He are significantly inconsistent with the predictions from Big Bang Nucleosynthesis (BBN when using the $Lambda$CDM cosmological model together with the value for $Omega_B h^2 = 0.0224pm0.0009$ from WMAP CMB fluctuations, with the value from BBN required to fit observed abundances being $0.009 < Omega_B h^2 < 0.013$. The dynamical 3-space theory is shown to predict a 20% hotter universe in the radiation-dominated epoch, which then results in a remarkable parameter-free agreement between the BBN and the WMAP value for $Omega_B h^2$. The dynamical 3-space also gives a parameter-free fit to the supernova redshift data, and predicts that the flawed $Lambda$CDM model would require $Omega_Lambda = 0.73$ and $Omega_M = 0.27$ to fit the 3-space dynamics Hubble expansion, and independently of the supernova data. These results amount to the discovery of new physics for the early universe that is matched by numerous other successful observational and experimental tests.

Dynamical 3-Space Predicts Hotter Early Universe: Resolves CMB-BBN 7-Li and 4-He Abundance Anomalies

Directory of Open Access Journals (Sweden)

Cahill R. T.

2010-01-01

Full Text Available The observed abundances of 7 Li and 4 He are significantly inconsistent with the pre- dictions from Big Bang Nucleosynthesis (BBN when using the CDM cosmolog- ical model together with the value for B h 2 = 0 : 0224 0 : 0009 from WMAP CMB fluctuations, with the value from BBN required to fit observed abundances being 0 : 009 < B h 2 < 0 : 013. The dynamical 3-space theory is shown to predict a 20% hot- ter universe in the radiation-dominated epoch, which then results in a remarkable parameter-free agreement between the BBN and the WMAP value for B h 2 . The dy- namical 3-space also gives a parameter-free fit to the supernova redshift data, and pre- dicts that the flawed CDM model would require = 0 : 73 and M = 0 : 27 to fit the 3-space dynamics Hubble expansion, and independently of the supernova data. These results amount to the discovery of new physics for the early universe that is matched by numerous other successful observational and experimental tests.

Neutrinos and nucleosynthesis in supernova

Energy Technology Data Exchange (ETDEWEB)

Solis, U [Instituto de Ciencias Nucleares, Departamento de Fisica de Altas EnergIas, Universidad Nacional Autonoma de Mexico (ICN-UNAM). Apartado Postal 70-543, 04510 Mexico, D.F. (Mexico); D' Olivo, J C [Instituto de Ciencias Nucleares, Departamento de Fisica de Altas EnergIas, Universidad Nacional Autonoma de Mexico (ICN-UNAM). Apartado Postal 70-543, 04510 Mexico, D.F. (Mexico); Cabral-Rosetti, L G [Departamento de Posgrado, Centro Interdisciplinario de Investigacion y Docencia en Educacion Tecnica (CIIDET), Av. Universidad 282 Pte., Col. Centro, A. Postal 752, C.P. 76000, Santiago de Queretaro, Qro. (Mexico)

2006-05-15

The type II supernova is considered as a candidate site for the production of heavy elements. The nucleosynthesis occurs in an intense neutrino flux, we calculate the electron fraction in this environment.

Neutrinos and nucleosynthesis in supernova

International Nuclear Information System (INIS)

Solis, U; D'Olivo, J C; Cabral-Rosetti, L G

2006-01-01

The type II supernova is considered as a candidate site for the production of heavy elements. The nucleosynthesis occurs in an intense neutrino flux, we calculate the electron fraction in this environment

Big bang nucleosynthesis constraints on bulk neutrinos

International Nuclear Information System (INIS)

Goh, H.S.; Mohapatra, R.N.

2002-01-01

We examine the constraints imposed by the requirement of successful nucleosynthesis on models with one large extra hidden space dimension and a single bulk neutrino residing in this dimension. We solve the Boltzmann kinetic equation for the thermal distribution of the Kaluza-Klein modes and evaluate their contribution to the energy density at the big bang nucleosynthesis epoch to constrain the size of the extra dimension R -1 ≡μ and the parameter sin 2 2θ which characterizes the mixing between the active and bulk neutrinos

Neutral currents, supernovae neutrinos, and nucleosynthesis

International Nuclear Information System (INIS)

Haxton, W.C.

1988-01-01

The inelastic interactions of neutrinos during stellar collapse and neutron star cooling are discussed. The primary mechanism for dissipative neutrino reactions is nuclear excitation by neutral current scattering, a process not included in standard descriptions of supernovae. Charge-current and neutral current ''preheating'' of iron lying outside the shock front appears to be significant in the few milliseconds near shock breakout. This could help produce a more energetic shock. During the cooling phase, the neutral current interactions of muon and taon neutrinos appear to be responsible for some interesting nucleosynthesis. I discuss two examples the production of fluorine and neutrino-induced r-process nucleosynthesis. 26 refs., 1 fig., 3 tabs

Bounds on long-lived charged massive particles from Big Bang nucleosynthesis

Energy Technology Data Exchange (ETDEWEB)

Jedamzik, Karsten, E-mail: jedamzik@lpta.univ-montp2.fr [Laboratoire de Physique Mathémathique et Théorique, CNRS, Université de Montpellier II, F-34095 Montpellier Cedex 5 (France)

2008-03-01

The Big Bang nucleosynthesis (BBN) process in the presence of charged massive particles (CHAMPs) is studied in detail. All currently known effects due to the existence of bound states between CHAMPs and nuclei, including possible late-time destruction of {sup 6}Li and {sup 7}Li, are included. The study sets conservative bounds on CHAMP abundances in the decay time range 3×10{sup 2} s∼<τ{sub x}∼<10{sup 12} s. It is stressed that the production of {sup 6}Li at early times T∼10 keV is overestimated by a factor ∼10 when the approximation of the Saha equation for the {sup 4}He bound state fraction is utilized. To obtain conservative limits on the abundance of CHAMPs, a Monte Carlo analysis with ∼3 × 10{sup 6} independent BBN runs, varying the reaction rates of 19 different reactions, is performed. The analysis yields the surprising result that, except for small areas in the particle parameter space, conservative constraints on the abundance of decaying charged particles are currently very close to those of neutral particles. It is shown that, in the case that the rates of a number of heretofore unconsidered reactions may be determined reliably in the future, it is conceivable that the limit on CHAMPs in the early Universe could be tightened by orders of magnitude.

Bounds on long-lived charged massive particles from Big Bang nucleosynthesis

Science.gov (United States)

Jedamzik, Karsten

2008-03-01

The Big Bang nucleosynthesis (BBN) process in the presence of charged massive particles (CHAMPs) is studied in detail. All currently known effects due to the existence of bound states between CHAMPs and nuclei, including possible late-time destruction of 6Li and 7Li, are included. The study sets conservative bounds on CHAMP abundances in the decay time range 3\\times 10^2~\\mathrm {s}\\lesssim \\tau_x\\lesssim 10^{12}~\\mathrm {s} . It is stressed that the production of 6Li at early times T~10 keV is overestimated by a factor ~10 when the approximation of the Saha equation for the 4He bound state fraction is utilized. To obtain conservative limits on the abundance of CHAMPs, a Monte Carlo analysis with ~3 × 106 independent BBN runs, varying the reaction rates of 19 different reactions, is performed. The analysis yields the surprising result that, except for small areas in the particle parameter space, conservative constraints on the abundance of decaying charged particles are currently very close to those of neutral particles. It is shown that, in the case that the rates of a number of heretofore unconsidered reactions may be determined reliably in the future, it is conceivable that the limit on CHAMPs in the early Universe could be tightened by orders of magnitude.

Was The Electromagnetic Spectrum A Blackbody Spectrum In The Early Universe?

International Nuclear Information System (INIS)

Opher, M.; Opher, R.

1997-01-01

It is generally assumed that the electromagnetic spectrum in the primordial universe was a blackbody spectrum in vacuum. We derive the electromagnetic spectrum based on the fluctuation-dissipation theorem that describes the electromagnetic fluctuations in a plasma. Our description includes thermal and collisional effects in a plasma. The electromagnetic spectrum obtained differs from a blackbody spectrum in vacuum at low frequencies. In particular, concentrating on the primordial nucleosynthesis era, it has more energy than the blackbody spectrum for frequencies less than 3ω pe to 6ω pe , where ω pe is the electron plasma frequency. copyright 1997 The American Physical Society

Primordial Nucleosynthesis

Science.gov (United States)

Coc, Alain

Primordial or big bang nucleosynthesis (BBN) is now a parameter free theory whose predictions are in good overall agreement with observations. However, the 7Li calculated abundance is significantly higher than the one deduced from spectroscopic observations. Most solutions to this lithium problem involve a source of extra neutrons that inevitably leads to an increase of the deuterium abundance. This seems now to be excluded by recent deuterium observations that have drastically reduced the uncertainty on D/H and also calls for improved precision on thermonuclear reaction rates.

How neutrino oscillations can induce an effective neutrino number of less than three during big bang nucleosynthesis

International Nuclear Information System (INIS)

Foot, R.; Volkas, R.R.

1997-01-01

Ordinary-sterile neutrino oscillations can generate significant neutrino asymmetry in the early Universe. In this paper we extend this work by computing the evolution of neutrino asymmetries and light element abundances during the big bang nucleosynthesis (BBN) epoch. We show that a significant electron-neutrino asymmetry can be generated in a way that is approximately independent of the oscillation parameters δm 2 and sin 2 2θ for a range of parameters in an interesting class of models. The numerical value of the asymmetry leads to the prediction that the effective number of neutrino flavors during BBN is either about 2.5 or 3.4, depending on the sign of the asymmetry. Interestingly, one class of primordial deuterium abundance data favors an effective number of neutrino flavors during the epoch of BBN of less than 3. copyright 1997 The American Physical Society

Big bang photosynthesis and pregalactic nucleosynthesis of light elements

Science.gov (United States)

Audouze, J.; Lindley, D.; Silk, J.

1985-01-01

Two nonstandard scenarios for pregalactic synthesis of the light elements (H-2, He-3, He-4, and Li-7) are developed. Big bang photosynthesis occurs if energetic photons, produced by the decay of massive neutrinos or gravitinos, partially photodisintegrate He-4 (formed in the standard hot big bang) to produce H-2 and He-3. In this case, primordial nucleosynthesis no longer constrains the baryon density of the universe, or the number of neutrino species. Alternatively, one may dispense partially or completely with the hot big bang and produce the light elements by bombardment of primordial gas, provided that He-4 is synthesized by a later generation of massive stars.

Big bang photosynthesis and pregalactic nucleosynthesis of light elements

International Nuclear Information System (INIS)

Audouze, J.; Lindley, D.; Silk, J.; and Laboratoire Rene Bernas, Orsay, France)

1985-01-01

Two nonstandard scenarios for pregalactic synthesis of the light elements ( 2 H, 3 He, 4 He, and 7 Li) are developed. Big bang photosynthesis occurs if energetic photons, produced by the decay of massive neutrinos or gravitinos, partially photodisintegrate 4 He (formed in the standard hot big bang) to produce 2 H and 3 He. In this case, primordial nucleosynthesis no longer constrains the baryon density of the universe, or the number of neutrino species. Alternatively, one may dispense partially or completely with the hot big bang and produce the light elements by bombardment of primordial gas, provided that 4 He is synthesized by a later generation of massive stars

Neutron-capture Nucleosynthesis in the First Stars

Science.gov (United States)

Roederer, Ian U.; Preston, George W.; Thompson, Ian B.; Shectman, Stephen A.; Sneden, Christopher

2014-04-01

Recent studies suggest that metal-poor stars enhanced in carbon but containing low levels of neutron-capture elements may have been among the first to incorporate the nucleosynthesis products of the first generation of stars. We have observed 16 stars with enhanced carbon or nitrogen using the MIKE Spectrograph on the Magellan Telescopes at Las Campanas Observatory and the Tull Spectrograph on the Smith Telescope at McDonald Observatory. We present radial velocities, stellar parameters, and detailed abundance patterns for these stars. Strontium, yttrium, zirconium, barium, europium, ytterbium, and other heavy elements are detected. In four stars, these heavy elements appear to have originated in some form of r-process nucleosynthesis. In one star, a partial s-process origin is possible. The origin of the heavy elements in the rest of the sample cannot be determined unambiguously. The presence of elements heavier than the iron group offers further evidence that zero-metallicity rapidly rotating massive stars and pair instability supernovae did not contribute substantial amounts of neutron-capture elements to the regions where the stars in our sample formed. If the carbon- or nitrogen-enhanced metal-poor stars with low levels of neutron-capture elements were enriched by products of zero-metallicity supernovae only, then the presence of these heavy elements indicates that at least one form of neutron-capture reaction operated in some of the first stars. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile, and The McDonald Observatory of The University of Texas at Austin.

Applications for fission product data to problems in stellar nucleosynthesis

International Nuclear Information System (INIS)

Mathews, G.J.

1983-10-01

A general overview of the nucleosynthesis mechanisms for heavy (A greater than or equal to 70) nuclei is presented with particular emphasis on critical data needs. The current state of the art in nucleosynthesis models is described and areas in which fission product data may provide useful insight are proposed. 33 references, 10 figures

Nonuniversal scalar-tensor theories and big bang nucleosynthesis

International Nuclear Information System (INIS)

Coc, Alain; Olive, Keith A.; Uzan, Jean-Philippe; Vangioni, Elisabeth

2009-01-01

We investigate the constraints that can be set from big bang nucleosynthesis on two classes of models: extended quintessence and scalar-tensor theories of gravity in which the equivalence principle between standard matter and dark matter is violated. In the latter case, and for a massless dilaton with quadratic couplings, the phase space of theories is investigated. We delineate those theories where attraction toward general relativity occurs. It is shown that big bang nucleosynthesis sets more stringent constraints than those obtained from Solar System tests.

Nonuniversal scalar-tensor theories and big bang nucleosynthesis

Science.gov (United States)

Coc, Alain; Olive, Keith A.; Uzan, Jean-Philippe; Vangioni, Elisabeth

2009-05-01

We investigate the constraints that can be set from big bang nucleosynthesis on two classes of models: extended quintessence and scalar-tensor theories of gravity in which the equivalence principle between standard matter and dark matter is violated. In the latter case, and for a massless dilaton with quadratic couplings, the phase space of theories is investigated. We delineate those theories where attraction toward general relativity occurs. It is shown that big bang nucleosynthesis sets more stringent constraints than those obtained from Solar System tests.

Observational constraints on secret neutrino interactions from big bang nucleosynthesis

Science.gov (United States)

Huang, Guo-yuan; Ohlsson, Tommy; Zhou, Shun

2018-04-01

We investigate possible interactions between neutrinos and massive scalar bosons via gϕν ¯ν ϕ (or massive vector bosons via gVν ¯γμν Vμ) and explore the allowed parameter space of the coupling constant gϕ (or gV) and the scalar (or vector) boson mass mϕ (or mV) by requiring that these secret neutrino interactions (SNIs) should not spoil the success of big bang nucleosynthesis (BBN). Incorporating the SNIs into the evolution of the early Universe in the BBN era, we numerically solve the Boltzmann equations and compare the predictions for the abundances of light elements with observations. It turns out that the constraint on gϕ and mϕ in the scalar-boson case is rather weak, due to a small number of degrees of freedom (d.o.f.). However, in the vector-boson case, the most stringent bound on the coupling gV≲6 ×10-10 at 95% confidence level is obtained for mV≃1 MeV , while the bound becomes much weaker gV≲8 ×10-6 for smaller masses mV≲10-4 MeV . Moreover, we discuss in some detail how the SNIs affect the cosmological evolution and the abundances of the lightest elements.

The quark-hadron phase transition and primordial nucleosynthesis

Science.gov (United States)

Hogan, Craig J.

1987-01-01

After presenting the current view of the processes taking place during the cosmological transition from 'quark soup' to normal hadron matter, attention is given to what happens to cosmological nucleosynthesis in the presence of small-scale baryon inhomogeneities. The QCD phase transition is among the plausible sources of this inhomogeneity. It is concluded that the formation of primordial 'quark nuggets' and other cold exotica requires very low entropy regions at the outset, and that even the more modest nonlinearities perturbing nucleosynthesis probably require some ingredient in addition to a quiescent, mildly supercooled transition.

Explosive nucleosynthesis in zones rich in hydrogen and helium

International Nuclear Information System (INIS)

Toussaint, Jacques.

1975-01-01

Explosive nucleosynthesis was studied for element with masses lower than that of 35 Cl at temperatures between 10 8 to 10 9 K. It is shown that in some astrophysical objects (Novae, Supernovae or super-massive-stars) an explosive nucleosynthesis of isotopes such as 3 He, 7 Li, 25 Mg or 29 Si is possible. The existence of those elements in the interstellar medium would make possible, ultimately, the formation of heavier elements (iron peak and above) [fr

Current rate of nucleosynthesis and its implications

Energy Technology Data Exchange (ETDEWEB)

Mallik, D C.V.

1981-06-01

Comparisons among stellar birthrate figures for stars of 05-9 and B0, 0.5 and 1 spectral type show that the current rate of nucleosynthesis is compatible with the idea of massive stars producing most of the metals only in the event that the stellar birthrate decreased with time. The current stellar evolution data, as well as observations, do not support the premise that intermediate mass stars are the source of the bulk of the nucleosynthesis in the galaxy. It is concluded that the limits of the Simple Model must be surpassed with the supposition of prompt initial enrichment, in order foo the stellar birthrate to be constant while the metals originate in the massive stars.

Type Ia Supernovae: Energetics, Neutronization and Nucleosynthesis

International Nuclear Information System (INIS)

Truran, James W.; Calder, Alan C.; Townsley, Dean M.; Seitenzahl, Ivo R.; Peng, Fang; Vladimirova, Natalia; Lamb, Donald Q.; Brown, Edward F.

2007-01-01

The utility of Type Ia supernovae, not simply as probes of the distance scale but also as a means of constraining the properties of dark energy, demands a significant improvement in theoretical predictions of their properties in outburst. To this end, we have given substantial effort to quantifying the energetics and nucleosynthesis properties of deflagration fronts in the interiors of the putative carbon-oxygen white dwarf progenitors of Type Ia thermonuclear supernovae. We briefly review some essential features of our flame model and its properties in this paper and discuss its implications both for our multidimensional numerical simulations of SNe Ia and for nucleosynthesis (specifically 56Ni production) in SNe Ia and Galactic chemical evolution

Corrections to primordial nucleosynthesis

International Nuclear Information System (INIS)

Dicus, D.A.; Kolb, E.W.; Gleeson, A.M.; Sudarshan, E.C.G.; Teplitz, V.L.; Turner, M.S.

1982-01-01

The changes in primordial nucleosynthesis resulting from small corrections to rates for weak processes that connect neutrons and protons are discussed. The weak rates are corrected by improved treatment of Coulomb and radiative corrections, and by inclusion of plasma effects. The calculations lead to a systematic decrease in the predicted 4 He abundance of about ΔY = 0.0025. The relative changes in other primoridal abundances are also 1 to 2%

Gravitino, dark matter candidate and implications for big bang nucleosynthesis

International Nuclear Information System (INIS)

Bailly, S.

2008-11-01

The Standard Model of particle physics was developed in the seventies. Despite many experimental successes, it presents many problems that can only be solved with models beyond the Standard Model. Supersymmetry is an interesting candidate, postulating a new symmetry between fermions and bosons. This model can also have interesting applications in cosmology. It offers potentially good candidates for dark matter, what represents 25% of the energy density of the Universe, and its nature is unknown. Another cosmological problem is the lithium problems in Big Bang Nucleosynthesis describing the production of light elements in the first seconds of the Universe. The lithium abundance predicted by the theory is inconsistent with observations. I study a scenario in which a supersymmetric particle, the gravitino, is the candidate for dark matter and the production of this particle through the decay of other supersymmetric particles may solve the lithium problems. (author)

Nucleosynthesis confronts an unstable inert 17 keV state

International Nuclear Information System (INIS)

Enqvist, K.; Kainulainen, K.; Thomson, M.

1991-01-01

We study the cosmological consequences of an inert 17 keV state mixing with the electron neutrino. We find that the nucleosynthesis upper bound on the primordial helium abundance prohibits the existence of such a state, unless its lifetime falls into the range 6x10 -4 s vac -2 s. In this range the decay occurs after the chemical decoupling of the electron neutrinos and before the beginning of the nucleosynthesis, with the result that the predicted helium abundance can be lower than what it would be in the standard scenario. (orig.)

Neutrinos and Big Bang Nucleosynthesis

Directory of Open Access Journals (Sweden)

Gary Steigman

2012-01-01

Full Text Available According to the standard models of particle physics and cosmology, there should be a background of cosmic neutrinos in the present Universe, similar to the cosmic microwave photon background. The weakness of the weak interactions renders this neutrino background undetectable with current technology. The cosmic neutrino background can, however, be probed indirectly through its cosmological effects on big bang nucleosynthesis (BBN and the cosmic microwave background (CMB radiation. In this BBN review, focused on neutrinos and more generally on dark radiation, the BBN constraints on the number of “equivalent neutrinos” (dark radiation, on the baryon asymmetry (baryon density, and on a possible lepton asymmetry (neutrino degeneracy are reviewed and updated. The BBN constraints on dark radiation and on the baryon density following from considerations of the primordial abundances of deuterium and helium-4 are in excellent agreement with the complementary results from the CMB, providing a suggestive, but currently inconclusive, hint of the presence of dark radiation, and they constrain any lepton asymmetry. For all the cases considered here there is a “lithium problem”: the BBN-predicted lithium abundance exceeds the observationally inferred primordial value by a factor of ~3.

Nuclear structure near the particle drip-lines and explosive nucleosynthesis processes

International Nuclear Information System (INIS)

Kratz, K.L.; Pfeiffer, B.; Moeller, P.; Thielemann, F.K.; Wiescher, M.

1999-01-01

In this paper, we discuss the nuclear physics input for a selected set of explosive nucleosynthesis scenarios leading to rapid proton-- and neutron--capture processes. Observables (like e.g. luminosity curves or elemental abundance distributions) witness the interplay between nuclear structure aspects near the particle drip-lines and the appropriate astrophysical environments, and can give guidance to and constraints on stellar conditions and the associated nucleosynthesis. (authors)

Chaotic amplification of neutrino chemical potentials by neutrino oscillations in big bang nucleosynthesis

International Nuclear Information System (INIS)

Shi, X.

1996-01-01

We investigate in detail the parameter space of active-sterile neutrino oscillations that amplifies neutrino chemical potentials at the epoch of big bang nucleosynthesis. We calculate the magnitude of the amplification and show evidence of chaos in the amplification process. We also discuss the implications of the neutrino chemical potential amplification in big bang nucleosynthesis. It is shown that with a ∼1 eV ν e , the amplification of its chemical potential by active-sterile neutrino oscillations can lower the effective number of neutrino species at big bang nucleosynthesis to significantly below three. copyright 1996 The American Physical Society

Chaotic amplification of neutrino chemical potentials by neutrino oscillations in big bang nucleosynthesis

Energy Technology Data Exchange (ETDEWEB)

Shi, X. [Department of Physics, Queen`s University, Kingston, Ontario, K7L 3N6 (CANADA)

1996-08-01

We investigate in detail the parameter space of active-sterile neutrino oscillations that amplifies neutrino chemical potentials at the epoch of big bang nucleosynthesis. We calculate the magnitude of the amplification and show evidence of chaos in the amplification process. We also discuss the implications of the neutrino chemical potential amplification in big bang nucleosynthesis. It is shown that with a {approximately}1 eV {nu}{sub {ital e}}, the amplification of its chemical potential by active-sterile neutrino oscillations can lower the effective number of neutrino species at big bang nucleosynthesis to significantly below three. {copyright} {ital 1996 The American Physical Society.}

Bulk yields of nucleosynthesis from massive stars

International Nuclear Information System (INIS)

Arnett, W.D.

1978-01-01

Preliminary estimates are made of the absolute yields of abundant nuclei synthesized in observed stars. The compositions of nine helium stars of mass 3 or =10M/sub sun/ is estimated. A variety of choices for the initial mass function (IMF) are used to calculate the yield per stellar generation. For standard choices of the (IMF) the absolute and relative yields of 12 C, 16 O, 20 Ne, 24 Mg, the Si to Ca group, and the iron group agree with solar system values, to the accuracy of the calculations. The relative yields are surprisingly insensitive to the slope of the IMF. In a second approach, using standard estimates (Ostriker, Richstone, and Thuan) for the current rate of stellar death, I find the present rate of nucleosynthesis in the solar neighborhood to be about 10%of the average rate over galactic history. This result is consistent with many standard models of galactic evolution (for example, the Schmidt model in which star formation goes as gas density squared). It appears that if the star formation rate is high enough to produce the stars we see around us, then the nucleosynthesis rate is large enough to produce the processed nuclei (except 4 He) seen in those stars. The typical nucleosynthesis source is massive (Mapprox. =30 M/sub sun/); the death rate of such stars is a small fraction (3-10%) of recent estimates of the total rate of supernovae

The role of Fe and Ni for s-process nucleosynthesis in the early Universe and for innovative nuclear technologies

CERN Multimedia

Manousos, A; Heil, M; Plag, R

The early universe was enriched in heavy elements by massive stars via their s- and r-process contributions. Ultra metal-poor stars were found to show abundance patterns that scale exactly with the solar r component. While this holds exactly for elements heavier than barium, there is still confusion about significant discrepancies in the mass region below A ${\\leq}$ 120. It is known that massive stars contribute significantly to the abundances between Fe and Zr. This so-called weak s-process component was found to exhibit large uncertainties due to the poorly known cross sections, especially in the Fe- i region. In view of this problem it is proposed to perform accurate state-of-the art measurements on highly enriched samples of the stable Fe and Ni isotopes at the n_TOF facility. Transformation of these results into significantly improved stellar cross section rates will allow to disentangle the s and r contributions observed in the oldest stars for a reliable comparison with galactic chemical evolution mode...

Primordial nucleosynthesis in inhomogeneous cosmologies: Ω = 1 with baryonic dark matter

International Nuclear Information System (INIS)

Mathews, G.J.; Sale, K.E.

1986-09-01

We consider the constraints on Ω from primordial nucleosynthesis in inhomogeneous cosmologies. We find that allowance for isothermal fluctuations significantly weakens the upper bound on the average value of Ω derived from the standard big bang. Under the plausible additional assumption that regions of high baryon density are preferentially absorbed into cold dark matter, the constraints from primordial nucleosynthesis can be satisfied for large values of Ω, including Ω = 1. 22 refs., 2 figs

Big-bang nucleosynthesis revisited

Science.gov (United States)

Olive, Keith A.; Schramm, David N.; Steigman, Gary; Walker, Terry P.

1989-01-01

The homogeneous big-bang nucleosynthesis yields of D, He-3, He-4, and Li-7 are computed taking into account recent measurements of the neutron mean-life as well as updates of several nuclear reaction rates which primarily affect the production of Li-7. The extraction of primordial abundances from observation and the likelihood that the primordial mass fraction of He-4, Y(sub p) is less than or equal to 0.24 are discussed. Using the primordial abundances of D + He-3 and Li-7 we limit the baryon-to-photon ratio (eta in units of 10 exp -10) 2.6 less than or equal to eta(sub 10) less than or equal to 4.3; which we use to argue that baryons contribute between 0.02 and 0.11 to the critical energy density of the universe. An upper limit to Y(sub p) of 0.24 constrains the number of light neutrinos to N(sub nu) less than or equal to 3.4, in excellent agreement with the LEP and SLC collider results. We turn this argument around to show that the collider limit of 3 neutrino species can be used to bound the primordial abundance of He-4: 0.235 less than or equal to Y(sub p) less than or equal to 0.245.

Nucleosynthesis and remnants in massive stars of solar metallicity

International Nuclear Information System (INIS)

Woosley, S.E.; Heger, A.

2007-01-01

Hans Bethe contributed in many ways to our understanding of the supernovae that happen in massive stars, but, to this day, a first principles model of how the explosion is energized is lacking. Nevertheless, a quantitative theory of nucleosynthesis is possible. We present a survey of the nucleosynthesis that occurs in 32 stars of solar metallicity in the mass range 12-120M sun . The most recent set of solar abundances, opacities, mass loss rates, and current estimates of nuclear reaction rates are employed. Restrictions on the mass cut and explosion energy of the supernovae based upon nucleosynthesis, measured neutron star masses, and light curves are discussed and applied. The nucleosynthetic results, when integrated over a Salpeter initial mass function (IMF), agree quite well with what is seen in the sun. We discuss in some detail the production of the long lived radioactivities, 26 Al and 60 Fe, and why recent model-based estimates of the ratio 60 Fe/ 26 Al are overly large compared with what satellites have observed. A major source of the discrepancy is the uncertain nuclear cross sections for the creation and destruction of these unstable isotopes

Electron screening and its effects on big-bang nucleosynthesis

International Nuclear Information System (INIS)

Wang Biao; Bertulani, C. A.; Balantekin, A. B.

2011-01-01

We study the effects of electron screening on nuclear reaction rates occurring during the big-bang nucleosynthesis epoch. The sensitivity of the predicted elemental abundances on electron screening is studied in detail. It is shown that electron screening does not produce noticeable results in the abundances unless the traditional Debye-Hueckel model for the treatment of electron screening in stellar environments is enhanced by several orders of magnitude. This work rules out electron screening as a relevant ingredient to big-bang nucleosynthesis, confirming a previous study [see Itoh et al., Astrophys. J. 488, 507 (1997)] and ruling out exotic possibilities for the treatment of screening beyond the mean-field theoretical approach.

Dark Matter Freeze-in Production in Fast-Expanding Universes

Science.gov (United States)

D'Eramo, Francesco; Fernandez, Nicolas; Profumo, Stefano

2018-02-01

If the dark matter is produced in the early universe prior to Big Bang nucleosynthesis, a modified cosmological history can drastically affect the abundance of relic dark matter particles. Here, we assume that an additional species to radiation dominates at early times, causing the expansion rate at a given temperature to be larger than in the standard radiation-dominated case. We demonstrate that, if this is the case, dark matter production via freeze-in (a scenario when dark matter interacts very weakly, and is dumped in the early universe out of equilibrium by decay or scattering processes involving particles in the thermal bath) is dramatically suppressed. We illustrate and quantitatively and analytically study this phenomenon for three different paradigmatic classes of freeze-in scenarios. For the frozen-in dark matter abundance to be as large as observations, couplings between the dark matter and visible-sector particles must be enhanced by several orders of magnitude. This sheds some optimistic prospects for the otherwise dire experimental and observational outlook of detecting dark matter produced by freeze-in.

Mapping the early Universe

Energy Technology Data Exchange (ETDEWEB)

Anon.

1991-06-15

From its unique vantage point 900 kilometres above the earth's surface, NASA's Cosmic Background Explorer (COBE) satellite has a privileged view of cosmic background radiation - the remnants of the early (radiation-dominated) Universe which followed the Big Bang some ten Gigayears ago, and possibly some subsequent history. In this way astroparticle physicists get a first peek at the quantum cosmology which moulded the infant Universe.

Mapping the early Universe

International Nuclear Information System (INIS)

Anon.

1991-01-01

From its unique vantage point 900 kilometres above the earth's surface, NASA's Cosmic Background Explorer (COBE) satellite has a privileged view of cosmic background radiation - the remnants of the early (radiation-dominated) Universe which followed the Big Bang some ten Gigayears ago, and possibly some subsequent history. In this way astroparticle physicists get a first peek at the quantum cosmology which moulded the infant Universe

Effects of sterile neutrino and extra-dimension on big bang nucleosynthesis

Science.gov (United States)

Jang, Dukjae; Kusakabe, Motohiko; Cheoun, Myung-Ki

2018-04-01

We study effects of the sterile neutrino in the five-dimensional universe on the big bang nucleosynthesis (BBN). Since the five-dimensional universe model leads to an additional term in the Friedmann equation and the energy density of the sterile neutrino increases the total energy density, this model can affect the primordial abundance via changing the cosmic expansion rate. The energy density of the sterile neutrino can be determined by a rate equation for production of the sterile neutrino. We show that not only the mixing angle and the mass of the sterile neutrino, but also a resonant effect in the oscillation between sterile and active neutrinos is important to determine a relic abundance of the sterile neutrino. In this study, we also investigate how the sterile neutrino in extra-dimensional model can affect the BBN, and constrain the parameters related to the above properties of the sterile neutrino by using the observational primordial abundances of light elements.

Discovery Mondays: The very early Universe

CERN Multimedia

2003-01-01

Copyright NASARetracing the very early Universe to understand why there is "something rather than nothing" is one of the challenges facing astrophysics today. It is also the theme of the third Discovery Monday, to be held in the Microcosm on 7 July, where you will be welcomed by a number of scientists. A professional astronomer will allow you to look through his telescope and explain how it works. A cosmologist will talk to you about the very early Universe and a CERN physicist will show you how it's possible to trap antimatter. The mirror of matter, antimatter should have existed in the same quantities as matter in the very early stages of the Universe but today it seems to have virtually disappeared. Perhaps the research being done at CERN will one day explain how an infinitesimal predominance of matter over antimatter resulted in such a richly structured Universe. Come along to the Microcosm on Monday, 7 July between 7.30 p.m. and 9.00 p.m. Entrance is free http://www.cern.ch/microcosm N.B.: The Discove...

Peculiarities of the early Universe (Universes) birth and positron annihilation

International Nuclear Information System (INIS)

Svetlov-Prokop'ev, E.P.

2003-01-01

Works on the problem of quantum birth of the Universe are reviewed. Possible peculiarities of electron-positron annihilation at the early stages of the Universe (s) birth in connection with black holes are considered. Possible concept of Eternity is discussed. (author)

Low-energy photodisintegration of the deuteron and Big-Bang nucleosynthesis

Energy Technology Data Exchange (ETDEWEB)

Tornow, W.; Czakon, N.G.; Howell, C.R.; Hutcheson, A.; Kelley, J.H.; Litvinenko, V.N.; Mikhailov, S.F.; Pinayev, I.V.; Weisel, G.J.; Witala, H

2003-11-06

The photon analyzing power for the photodisintegration of the deuteron was measured for seven gamma-ray energies between 2.39 and 4.05 MeV using the linearly polarized gamma-ray beam of the high-intensity gamma-ray source at the Duke Free-Electron Laser Laboratory. The data provide a stringent test of theoretical calculations for the inverse reaction, the neutron-proton radiative capture reaction at energies important for Big-Bang nucleosynthesis. Our data are in excellent agreement with potential model and effective field theory calculations. Therefore, the uncertainty in the baryon density {omega}{sub B}h{sup 2} obtained from Big-Bang Nucleosynthesis can be reduced at least by 20%.

Low-energy photodisintegration of the deuteron and Big-Bang nucleosynthesis

International Nuclear Information System (INIS)

Tornow, W.; Czakon, N.G.; Howell, C.R.; Hutcheson, A.; Kelley, J.H.; Litvinenko, V.N.; Mikhailov, S.F.; Pinayev, I.V.; Weisel, G.J.; Witala, H.

2003-01-01

The photon analyzing power for the photodisintegration of the deuteron was measured for seven gamma-ray energies between 2.39 and 4.05 MeV using the linearly polarized gamma-ray beam of the high-intensity gamma-ray source at the Duke Free-Electron Laser Laboratory. The data provide a stringent test of theoretical calculations for the inverse reaction, the neutron-proton radiative capture reaction at energies important for Big-Bang nucleosynthesis. Our data are in excellent agreement with potential model and effective field theory calculations. Therefore, the uncertainty in the baryon density Ω B h 2 obtained from Big-Bang Nucleosynthesis can be reduced at least by 20%

Stochastic evolution of cosmological parameters in the early universe

Indian Academy of Sciences (India)

We develop a stochastic formulation of cosmology in the early universe, after considering the scatter in the redshift-apparent magnitude diagram in the early epochs as an observational evidence for the non-deterministic evolution of early universe. We consider the stochastic evolution of density parameter in the early ...

Particle Physics Catalysis of Thermal Big Bang Nucleosynthesis

International Nuclear Information System (INIS)

Pospelov, Maxim

2007-01-01

We point out that the existence of metastable, τ>10 3 s, negatively charged electroweak-scale particles (X - ) alters the predictions for lithium and other primordial elemental abundances for A>4 via the formation of bound states with nuclei during big bang nucleosynthesis. In particular, we show that the bound states of X - with helium, formed at temperatures of about T=10 8 K, lead to the catalytic enhancement of 6 Li production, which is 8 orders of magnitude more efficient than the standard channel. In particle physics models where subsequent decay of X - does not lead to large nonthermal big bang nucleosynthesis effects, this directly translates to the level of sensitivity to the number density of long-lived X - particles (τ>10 5 s) relative to entropy of n X - /s -17 , which is one of the most stringent probes of electroweak scale remnants known to date

Thermalisation of light sterile neutrinos in the early universe

DEFF Research Database (Denmark)

Hannestad, Steen; Tamborra, Irene; Tram, Thomas

2012-01-01

on the current cosmological data have been derived using simplified assumptions about thermalisation of the sterile neutrino at the Big Bang Nucleosynthesis (BBN) epoch. These assumptions are not necessarily justified and here we solve the full quantum kinetic equations in the (1 active + 1 sterile) scenario...

Primordial nucleosynthesis revisited via Trojan Horse Results

Directory of Open Access Journals (Sweden)

Pizzone R.G.

2016-01-01

Full Text Available Big Bang Nucleosynthesis (BBN requires several nuclear physics inputs and nuclear reaction rates. An up-to-date compilation of direct cross sections of d(d,pt, d(d,n3He and 3He(d,p4He reactions is given, being these ones among the most uncertain bare-nucleus cross sections. An intense experimental effort has been carried on in the last decade to apply the Trojan Horse Method (THM to study reactions of relevance for the BBN and measure their astrophysical S(E-factor. The reaction rates and the relative error for the four reactions of interest are then numerically calculated in the temperature ranges of relevance for BBN (0.01nucleosynthesis calculations in order to evaluate their impact on the calculated primordial abundances of D, 3,4He and 7Li. These were compared with the observational primordial abundance estimates in different astrophysical sites. A comparison was also performed with calculations using other reaction rates compilations available in literature.

Challenges in nucleosynthesis of trans-iron elements

International Nuclear Information System (INIS)

Rauscher, T.

2014-01-01

Nucleosynthesis beyond Fe poses additional challenges not encountered when studying astrophysical processes involving light nuclei. Astrophysical sites and conditions are not well known for some of the processes involved. On the nuclear physics side, different approaches are required, both in theory and experiment. The main differences and most important considerations are presented for a selection of nucleosynthesis processes and reactions, specifically the s-, r-, γ-, and νp-processes. Among the discussed issues are uncertainties in sites and production conditions, the difference between laboratory and stellar rates, reaction mechanisms, important transitions, thermal population of excited states, and uncertainty estimates for stellar rates. The utility and limitations of indirect experimental approaches are also addressed. The presentation should not be viewed as confining the discussed problems to the specific processes. The intention is to generally introduce the concepts and possible pitfalls along with some examples. Similar problems may apply to further astrophysical processes involving nuclei from the Fe region upward and/or at high plasma temperatures. The framework and strategies presented here are intended to aid the conception of future experimental and theoretical approaches

Impact of neutrino flavor oscillations on the neutrino-driven wind nucleosynthesis of an electron-capture supernova

NARCIS (Netherlands)

Pllumbi, E.; Tamborra, I.; Wanajo, S.; Janka, H.-T.; Hüdepohl, L.

2015-01-01

Neutrino oscillations, especially to light sterile states, can affect nucleosynthesis yields because of their possible feedback effect on the electron fraction (Ye). For the first time, we perform nucleosynthesis calculations for neutrino-driven wind trajectories from the neutrino-cooling phase of

Gravitino in the early Universe. A model of extra-dimension and a model of dark matter

International Nuclear Information System (INIS)

Gherson, D.

2007-10-01

This work can be related to the Horava-Witten M-theory in which the Universe could appear 5 dimensional at a stage of its evolution but also to theories of Baryogenesis through Lepto-genesis which imply high reheating temperatures after Inflation. The studied cosmological model is within the framework of a 5 dimensional supergravity with the extra-dimension compactified on an orbifold circle, where the matter and gauge field are located on one of the two branes localised at the orbifold fixed points and where the supergravity fields can propagate in the whole spatial dimensions. In the model, the Dark matter is made of neutralino which is supposed to be the lightest supersymmetric particle. We have shown that there are curves of constraints between the size of the extra-dimension and the reheating temperature of the Universe after Inflation. The constraints come from the measurements of the amount of Dark matter in the Universe and from the model of the Big Bang Nucleosynthesis of light elements. (author)

Dirac fields in loop quantum gravity and big bang nucleosynthesis

International Nuclear Information System (INIS)

Bojowald, Martin; Das, Rupam; Scherrer, Robert J.

2008-01-01

Big bang nucleosynthesis requires a fine balance between equations of state for photons and relativistic fermions. Several corrections to equation of state parameters arise from classical and quantum physics, which are derived here from a canonical perspective. In particular, loop quantum gravity allows one to compute quantum gravity corrections for Maxwell and Dirac fields. Although the classical actions are very different, quantum corrections to the equation of state are remarkably similar. To lowest order, these corrections take the form of an overall expansion-dependent multiplicative factor in the total density. We use these results, along with the predictions of big bang nucleosynthesis, to place bounds on these corrections and especially the patch size of discrete quantum gravity states.

Constraints on vacuum energy from structure formation and Nucleosynthesis

Energy Technology Data Exchange (ETDEWEB)

Adams, Fred C.; Grohs, Evan [Physics Department, University of Michigan, 450 Church Street, Ann Arbor, MI, 48109 (United States); Alexander, Stephon [Physics Department, Brown University, 6127 Wilder Laboratory, Providence, RI, 02912 (United States); Mersini-Houghton, Laura, E-mail: fca@umich.edu, E-mail: stephon_alexander@brown.edu, E-mail: egrohs@umich.edu, E-mail: mersini@physics.unc.edu [Physics Department, University of North Carolina, 120 E. Cameron Avenue, Chapel Hill, NC, 27599 (United States)

2017-03-01

This paper derives an upper limit on the density ρ{sub Λ} of dark energy based on the requirement that cosmological structure forms before being frozen out by the eventual acceleration of the universe. By allowing for variations in both the cosmological parameters and the strength of gravity, the resulting constraint is a generalization of previous limits. The specific parameters under consideration include the amplitude Q of the primordial density fluctuations, the Planck mass M {sub pl}, the baryon-to-photon ratio η, and the density ratio Ω {sub M} /Ω {sub b} . In addition to structure formation, we use considerations from stellar structure and Big Bang Nucleosynthesis (BBN) to constrain these quantities. The resulting upper limit on the dimensionless density of dark energy becomes ρ{sub Λ}/ M {sub pl}{sup 4} < 10{sup −90}, which is ∼30 orders of magnitude larger than the value in our universe ρ{sub Λ}/ M {sub pl}4 ∼ 10{sup −120}. This new limit is much less restrictive than previous constraints because additional parameters are allowed to vary. With these generalizations, a much wider range of universes can develop cosmic structure and support observers. To constrain the constituent parameters, new BBN calculations are carried out in the regime where η and G = M {sub pl}{sup −2} are much larger than in our universe. If the BBN epoch were to process all of the protons into heavier elements, no hydrogen would be left behind to make water, and the universe would not be viable. However, our results show that some hydrogen is always left over, even under conditions of extremely large η and G , so that a wide range of alternate universes are potentially habitable.

Primordial chemistry: an overview

International Nuclear Information System (INIS)

Signore, Monique; Puy, Denis

1999-01-01

In the standard Big Bang model, the light elements in the cosmos -hydrogen and helium but also deuterium and lithium- were created in the very early Universe. The main problem is to connect what we can actually observe to day with the standard Big Bang nucleosynthesis predictions essentially because of uncertainties in modeling their evolution since the Big Bang. After a brief review of the primordial nucleosynthesis -predictions and observations of the primordial abundances- we present the preliminary studies of the primordial chemistry: molecular formation and evolution in the early Universe

Particle physics catalysis of thermal big bang nucleosynthesis.

Science.gov (United States)

Pospelov, Maxim

2007-06-08

We point out that the existence of metastable, tau>10(3) s, negatively charged electroweak-scale particles (X-) alters the predictions for lithium and other primordial elemental abundances for A>4 via the formation of bound states with nuclei during big bang nucleosynthesis. In particular, we show that the bound states of X- with helium, formed at temperatures of about T=10(8) K, lead to the catalytic enhancement of 6Li production, which is 8 orders of magnitude more efficient than the standard channel. In particle physics models where subsequent decay of X- does not lead to large nonthermal big bang nucleosynthesis effects, this directly translates to the level of sensitivity to the number density of long-lived X- particles (tau>10(5) s) relative to entropy of nX-/s less, approximately <3x10(-17), which is one of the most stringent probes of electroweak scale remnants known to date.

WMAP - A Glimpse of the Early Universe

Science.gov (United States)

Wollack, Edward

2009-01-01

The early Universe was incredibly hot, dense, and homogeneous. A powerful probe of this time is provided by the relic radiation which we refer to today as the Cosmic Microwave Background (CMB). Images produced from this light contain the earliest glimpse of the Universe after the "Big Bang" and the signature of the evolution of its contents. By exploiting these clues, precise constraints on the age, mass density, and geometry of the early Universe can be derived. The history of this intriguing cosmological detective story will be reviewed. Recent results from NASA's Wilkinson Microwave Anisotropy Probe (WMAP) will be presented.

Inhomogeneous Big Bang Nucleosynthesis Revisited

OpenAIRE

Lara, J. F.; Kajino, T.; Mathews, G. J.

2006-01-01

We reanalyze the allowed parameters for inhomogeneous big bang nucleosynthesis in light of the WMAP constraints on the baryon-to-photon ratio and a recent measurement which has set the neutron lifetime to be 878.5 +/- 0.7 +/- 0.3 seconds. For a set baryon-to-photon ratio the new lifetime reduces the mass fraction of He4 by 0.0015 but does not significantly change the abundances of other isotopes. This enlarges the region of concordance between He4 and deuterium in the parameter space of the b...

Nuclear weak interactions, supernova nucleosynthesis and neutrino oscillation

Science.gov (United States)

Kajino, Toshitaka

2013-07-01

We study the nuclear weak response in light-to-heavy mass nuclei and calculate neutrino-nucleus cross sections. We apply these cross sections to the explosive nucleosynthesis in core-collapse supernovae and find that several isotopes of rare elements 7Li, 11B, 138La, 180Ta and several others are predominantly produced by the neutrino-process nucleosynthesis. We discuss how to determine the suitable neutrino spectra of three different flavors and their anti-particles in order to explain the observed solar system abundances of these isotopes, combined with Galactic chemical evolution of the light nuclei and the heavy r-process elements. Light-mass nuclei like 7Li and 11B, which are produced in outer He-layer, are strongly affected by the neutrino flavor oscillation due to the MSW (Mikheyev-Smirnov-Wolfenstein) effect, while heavy-mass nuclei like 138La, 180Ta and r-process elements, which are produced in the inner O-Ne-Mg layer or the atmosphere of proto-neutron star, are likely to be free from the MSW effect. Using such a different nature of the neutrino-process nucleosynthesis, we study the neutrino oscillation effects on their abundances, and propose a new novel method to determine the unknown neutrino oscillation parameters, θ13 and mass hierarchy, simultaneously. There is recent evidence that some SiC X grains from the Murchison meteorite may contain supernova-produced neutrino-process 11B and 7Li encapsulated in the grains. Combining the recent experimental constraints on θ13, we show that although the uncertainties are still large, our method hints at a marginal preference for an inverted neutrino mass hierarchy for the first time.

Laboratory approaches of nuclear reactions involved in primordial and stellar nucleosynthesis

International Nuclear Information System (INIS)

Rolfs, C.; California Inst. of Tech., Pasadena

1986-01-01

Laboratory-based studies of primordial and stellar nucleosynthesis are reviewed, with emphasis on the nuclear reactions induced by charged particles. The analytical approach used to investigate nuclear reactions associated with stellar reactions is described, as well as the experimental details and procedures used to investigate nuclear reactions induced by charged particles. The present knowledge of some of the key reactions involved in primordial nucleosynthesis is discussed, along with the progress and problems of nuclear reactions involved in the hydrogen and helium burning phases of a star. Finally, a description is given of new experimental techniques which might be useful for future experiments in the field of nuclear astrophysics. (U.K.)

Computational Astrophysics Consortium 3 - Supernovae, Gamma-Ray Bursts and Nucleosynthesis

Energy Technology Data Exchange (ETDEWEB)

Woosley, Stan [Univ. of California, Santa Cruz, CA (United States)

2014-08-29

Final project report for UCSC's participation in the Computational Astrophysics Consortium - Supernovae, Gamma-Ray Bursts and Nucleosynthesis. As an appendix, the report of the entire Consortium is also appended.

Toward a self-consistent and unitary reaction network for big bang nucleosynthesis

International Nuclear Information System (INIS)

Paris, Mark W.; Brown, Lowell S.; Hale, Gerald M.; Hayes-Sterbenz, Anna C.; Jungman, Gerard; Kawano, Toshihiko; Fuller, George M.; Grohs, Evan B.; Kunieda, Satoshi

2014-01-01

Unitarity, the mathematical expression of the conservation of probability in multichannel reactions, is an essential ingredient in the development of accurate nuclear reaction networks appropriate for nucleosynthesis in a variety of environments. We describe our ongoing program to develop a 'unitary reaction network' for the big-bang nucleosynthesis environment and look at an example of the need and power of unitary parametrizations of nuclear scattering and reaction data. Recent attention has been focused on the possible role of the 9 B compound nuclear system in the resonant destruction of 7 Li during primordial nucleosynthesis. We have studied reactions in the 9 B compound system with a multichannel, two-body unitary R-matrix code (EDA) using the known elastic and reaction data, in a four-channel treatment. The data include elastic 6 Li( 3 He, 3 He) 6 Li differential cross sections from 0.7 to 2.0 MeV, integrated reaction cross sections for energies from 0.7 to 5.0 MeV for 6 Li( 3 He,p) 8 Be* and from 0.4 to 5.0 MeV for the 6 Li( 3 He,γ) 7 Be reaction. Capture data have been added to the previous analysis with integrated cross section measurements from 0.7 to 0.825 MeV for 6 Li( 3 He,γ) 9 B. The resulting resonance parameters are compared with tabulated values from TUNL Nuclear Data Group analyses. Previously unidentified resonances are noted and the relevance of this analysis and a unitary reaction network for big-bang nucleosynthesis are emphasized. (author)

Big bang nucleosynthesis with a varying fine structure constant and nonstandard expansion rate

International Nuclear Information System (INIS)

Ichikawa, Kazuhide; Kawasaki, Masahiro

2004-01-01

We calculate the primordial abundances of light elements produced during big bang nucleosynthesis when the fine structure constant and/or the cosmic expansion rate take nonstandard values. We compare them with the recent values of observed D, 4 He, and 7 Li abundances, which show a slight inconsistency among themselves in the standard big bang nucleosynthesis scenario. This inconsistency is not solved by considering either a varying fine structure constant or a nonstandard expansion rate separately but solutions are found by their simultaneous existence

Unveiling secret interactions among sterile neutrinos with big-bang nucleosynthesis

Science.gov (United States)

Saviano, Ninetta; Pisanti, Ofelia; Mangano, Gianpiero; Mirizzi, Alessandro

2014-12-01

Short-baseline neutrino anomalies suggest the existence of low-mass [m ˜O (1 ) eV ] sterile neutrinos νs. These would be efficiently produced in the early universe by oscillations with active neutrino species, leading to a thermal population of the sterile states seemingly incompatible with cosmological observations. In order to relieve this tension it has been recently speculated that new "secret" interactions among sterile neutrinos, mediated by a massive gauge boson X (with MX≪MW), can inhibit or suppress the sterile neutrino thermalization, due to the production of a large matter potential term. We note however, that they also generate strong collisional terms in the sterile neutrino sector that induce an efficient sterile neutrino production after a resonance in matter is encountered, increasing their contribution to the number of relativistic particle species Neff. Moreover, for values of the parameters of the νs-νs interaction for which the resonance takes place at temperature T ≲few MeV , significant distortions are produced in the electron (anti)neutrino spectra, altering the abundance of light element in big bang nucleosynthesis (BBN). Using the present determination of 4He and deuterium primordial abundances we determine the BBN constraints on the model parameters. We find that 2H/H density ratio exclude much of the parameter space if one assumes a baryon density at the best fit value of Planck experiment, ΩBh2=0.02207 , while bounds become weaker for a higher ΩBh2=0.02261 , the 95% C.L. upper bound of Planck. Due to the large error on its experimental determination, the helium mass fraction Yp gives no significant bounds.

Bursts from the very early universe

International Nuclear Information System (INIS)

Silk, J.; Stodolsky, L.

2006-01-01

Bursts of weakly interacting particles such as neutrinos or even more weakly interacting particles such as wimps and gravitons from the very early universe would offer a much deeper 'look back time' to early epochs than is possible with photons. We consider some of the issues related to the existence of such bursts and their detectability. Characterizing the burst rate by a probability P per Hubble four-volume we find, for events in the radiation-dominated era, that the natural unit of description is the present intensity of the CMB times P. The existence of such bursts would make the observation of phenomena associated with very early times in cosmology at least conceptually possible. One might even hope to probe the transplanckian epoch if complexes more weakly interacting than the graviton can exist. Other conceivable applications include the potential detectability of the formation of 'pocket universes' in a multiverse

Cosmology and the early universe

CERN Document Server

Di Bari, Pasquale

2018-01-01

This book discusses cosmology from both an observational and a strong theoretical perspective. The first part focuses on gravitation, notably the expansion of the universe and determination of cosmological parameters, before moving onto the main emphasis of the book, the physics of the early universe, and the connections between cosmological models and particle physics. Readers will gain a comprehensive account of cosmology and the latest observational results, without requiring prior knowledge of relativistic theories, making the text ideal for students.

Monte Carlo calculations for r-process nucleosynthesis

Energy Technology Data Exchange (ETDEWEB)

Mumpower, Matthew Ryan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2015-11-12

A Monte Carlo framework is developed for exploring the impact of nuclear model uncertainties on the formation of the heavy elements. Mass measurements tightly constrain the macroscopic sector of FRDM2012. For r-process nucleosynthesis, it is necessary to understand the microscopic physics of the nuclear model employed. A combined approach of measurements and a deeper understanding of the microphysics is thus warranted to elucidate the site of the r-process.

Toward a self-consistent and unitary reaction network for big bang nucleosynthesis

Energy Technology Data Exchange (ETDEWEB)

Paris, Mark W.; Brown, Lowell S.; Hale, Gerald M.; Hayes-Sterbenz, Anna C.; Jungman, Gerard; Kawano, Toshihiko, E-mail: mparis@lanl.gov [Los Alamos National Laboratory, Los Alamos, New Mexico (United States); Fuller, George M.; Grohs, Evan B. [Department of Physics, University of California, San Diego, La Jolla, CA (United States); Kunieda, Satoshi [Nuclear Data Center, Japan Atomic Energy Agency, Tokai-mura Naka-gun, Ibaraki (Japan)

2014-07-01

Unitarity, the mathematical expression of the conservation of probability in multichannel reactions, is an essential ingredient in the development of accurate nuclear reaction networks appropriate for nucleosynthesis in a variety of environments. We describe our ongoing program to develop a 'unitary reaction network' for the big-bang nucleosynthesis environment and look at an example of the need and power of unitary parametrizations of nuclear scattering and reaction data. Recent attention has been focused on the possible role of the {sup 9}B compound nuclear system in the resonant destruction of {sup 7}Li during primordial nucleosynthesis. We have studied reactions in the {sup 9}B compound system with a multichannel, two-body unitary R-matrix code (EDA) using the known elastic and reaction data, in a four-channel treatment. The data include elastic {sup 6}Li({sup 3}He,{sup 3}He){sup 6}Li differential cross sections from 0.7 to 2.0 MeV, integrated reaction cross sections for energies from 0.7 to 5.0 MeV for {sup 6}Li({sup 3}He,p){sup 8}Be* and from 0.4 to 5.0 MeV for the {sup 6}Li({sup 3}He,γ){sup 7}Be reaction. Capture data have been added to the previous analysis with integrated cross section measurements from 0.7 to 0.825 MeV for {sup 6}Li({sup 3}He,γ){sup 9}B. The resulting resonance parameters are compared with tabulated values from TUNL Nuclear Data Group analyses. Previously unidentified resonances are noted and the relevance of this analysis and a unitary reaction network for big-bang nucleosynthesis are emphasized. (author)

The Toy model: Understanding the early universe

Science.gov (United States)

Fisher, Peter H.; Price, Richard H.

2018-04-01

In many branches of science, progress is being made by taking advantage of insights from other branches of science. Cosmology, the structure and evolution of the universe, is certainly an area that is currently beset by problems in understanding. We show here that the scientific insights from the studies of early childhood development, in particular, those of Piaget, give a new way of looking at the early universe. This new approach can not only be invaluable in undergraduate teaching, but can even be the basis of semi-quantitative predictions.

Bursts from the very early universe

Energy Technology Data Exchange (ETDEWEB)

Silk, J. [Department of Physics, University of Oxford, Oxford OX1 3RH (United Kingdom); Stodolsky, L. [Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Munich (Germany)]. E-mail: les@mppmu.mpg.de

2006-07-27

Bursts of weakly interacting particles such as neutrinos or even more weakly interacting particles such as wimps and gravitons from the very early universe would offer a much deeper 'look back time' to early epochs than is possible with photons. We consider some of the issues related to the existence of such bursts and their detectability. Characterizing the burst rate by a probability P per Hubble four-volume we find, for events in the radiation-dominated era, that the natural unit of description is the present intensity of the CMB times P. The existence of such bursts would make the observation of pheno associated with very early times in cosmology at least conceptually possible. One might even hope to probe the transplanckian epoch if complexes more weakly interacting than the graviton can exist. Other conceivable applications include the potential detectability of the formation of 'pocket universes' in a multiverse.

Supernova neutrinos, giant resonances, and nucleosynthesis

International Nuclear Information System (INIS)

Haxton, W.

1990-01-01

Almost all of the 3·10 53 ergs liberated in a core collapse supernova is radiated as neutrinos by the cooling neutron star. The neutrinos can excite nuclei in the mantle of the star by their neutral and charged current reactions. I argue that the resulting spallation reactions are an important nucleosynthesis mechanism that may be responsible for the galactic abundances of 7 Li, 11 B, 19 F, 138 La, 180 Ta, and approximately a dozen other light nuclei. 18 refs., 1 fig., 1 tab

Constraining neutrino physics with big bang nucleosynthesis and cosmic microwave background radiation

International Nuclear Information System (INIS)

Hansen, S.H.; Melchiorri, A.; Mangano, G.; Miele, G.; Pisanti, O.

2002-01-01

We perform a likelihood analysis of the recent results on the anisotropy of cosmic microwave background radiation from the BOOMERanG and DASI experiments to show that they single out an effective number of neutrinos in good agreement with standard big bang nucleosynthesis. We also consider degenerate big bang nucleosynthesis to provide new bounds on effective relativistic degrees of freedom N ν and, in particular, on the neutrino chemical potential ξ α . When including supernova type Ia data we find, at 2σ, N ν ≤7 and -0.01≤ξ e ≤0.22, vertical bar ξ μ,τ vertical bar ≤2.6

Varying couplings in the early universe: Correlated variations of α and G

International Nuclear Information System (INIS)

Martins, C. J. A. P.; Menegoni, Eloisa; Galli, Silvia; Mangano, Gianpiero; Melchiorri, Alessandro

2010-01-01

The cosmic microwave background anisotropies provide a unique opportunity to constrain simultaneous variations of the fine-structure constant α and Newton's gravitational constant G. Those correlated variations are possible in a wide class of theoretical models. In this brief paper we show that the current data, assuming that particle masses are constant, give no clear indication for such variations, but already prefer that any relative variations in α should be of the same sign of those of G for variations of ∼1%. We also show that a cosmic complementarity is present with big bang nucleosynthesis and that a combination of current CMB and big bang nucleosynthesis data strongly constraints simultaneous variations in α and G. We finally discuss the future bounds achievable by the Planck satellite mission.

Connecting QGP-Heavy Ion Physics to the Early Universe

Energy Technology Data Exchange (ETDEWEB)

Rafelski, Johann

2013-10-15

We discuss properties and evolution of quark-gluon plasma in the early Universe and compare to laboratory heavy ion experiments. We describe how matter and antimatter emerged from a primordial soup of quarks and gluons. We focus our discussion on similarities and differences between the early Universe and the laboratory experiments.

Photodisintegration of deuterium and big bang nucleosynthesis

International Nuclear Information System (INIS)

Hara, K.Y.; Utsunomiya, H.; Goko, S.; Akimune, H.; Yamagata, T.; Ohta, M.; Toyokawa, H.; Kudo, K.; Uritani, A.; Shibata, Y.; Lui, Y.-W.; Ohgaki, H.

2003-01-01

Photodisintegration cross sections were measured for deuterium with Laser-Compton scattering γ beams at seven energies near threshold. Combined with the preceding data, R(E)=N a σv for the p(n,γ)D reaction is for the first time evaluated based on experimental data with 6% uncertainty in the energy region relevant to the big bang nucleosynthesis (BBN). The result confirms the theoretical evaluation on which the BBN in the precision era relies

Galaxies in the Early Universe

DEFF Research Database (Denmark)

Krogager, Jens-Kristian

Understanding how galaxies evolved from the early Universe through cosmic time is a fundamental part of modern astrophysics. In order to study this evolution it is important to sample the galaxies at various times in a consistent way through time. In regular luminosity selected samples, our...

Physics of the early universe

International Nuclear Information System (INIS)

Klinkhamer, F.R.

1983-01-01

In this thesis, the author has assembled his papers on elementary particle physics which are of importance for studying cosmology viz. the physics of the early universe. A rather detailed introduction reviewing basic principles and current trends in the relation particle physics/cosmology precedes the papers. (Auth.)

Big-Bang Nucleosynthesis

CERN Document Server

Fields, Brian D.; Sarkar, Subir

2014-01-01

A critical review is given of the current status of cosmological nucleosynthesis. In the framework of the Standard Model with 3 types of relativistic neutrinos, the baryon-to-photon ratio, η, corresponding to the inferred primordial abundances of deuterium and helium-4 is consistent with the independent determination of η from observations of anisotropies in the cosmic microwave background. However the primordial abundance of lithium-7 inferred from observations is significantly below its expected value. Taking systematic uncertainties in the abundance estimates into account, there is overall concordance in the range η=(5.7−6.7)×10−10 at 95% CL (corresponding to a cosmological baryon density ΩBh2=0.021−0.025). The D and He-4 abundances, when combined with the CMB determination of η, provide the bound Nν=3.28±0.28 on the effective number of neutrino species. Other constraints on new physics are discussed briefly.

Physics of the early universe

International Nuclear Information System (INIS)

Brandenberger, R.H.

1987-01-01

When studying the evolution of the very early universe it is necessary to use a description of matter which is appropriate at very high energies, namely in terms of quantum fields. In such models there may be a period during which the ratio of pressure and energy density is - 1, an equation of state which leads to an exponential expansion of the universe (inflation). There may also arise stable topological defects similar to vortex lines in condensed matter physics. These defects (cosmic strings) form seeds about which gas can accrete to form galaxies and clusters of galaxies. The author reviews inflation and cosmic strings, emphasizing their role in generating the energy density perturbations which are required in order to explain the existence of structures in the universe

Photinos and primordial nucleosynthesis

International Nuclear Information System (INIS)

Salati, P.

1986-07-01

Photinos are among the most interesting particles predicted by supersymmetric theories. If they exist they should influence in many ways the results of the primordial nucleosynthesis i.e. the predicted primordial abundances of D, 3 He, 4 He (and 7 Li). If photinos are stable, cosmological constraints restrict their possible mass to be either very light (M∼ γ γ > a few GeV), depending on the slepton and squark masses. In the case where photinos are unstable, they could create high energy photons able to photodisintegrate the light elements. The comparison between the predicted and the observed abundances allows to restrict significantly the photino mass-lifetime range: roughly speaking photinos of relatively high mass (M∼ γ > 150 MeV) and low time scale ( 3 sec) are compatible with these abundances

Neutrinos and Nucleosynthesis in Hot and Dense Matter

Energy Technology Data Exchange (ETDEWEB)

Fuller, George [Univ. of California, San Diego, CA (United States)

2016-01-14

The Topical Collaboration for Neutrinos and Nucleosynthesis in Hot and Dense matter brought together researchers from a variety of nuclear science specialties and a number of institutions to address nuclear physics and neutrino physics problems associated with dense matter and the origin of the elements. See attached final technical reports for (1) the UCSD award and (2) a copy of the report for the whole TC

Shocks in the Early Universe.

Science.gov (United States)

Pen, Ue-Li; Turok, Neil

2016-09-23

We point out a surprising consequence of the usually assumed initial conditions for cosmological perturbations. Namely, a spectrum of Gaussian, linear, adiabatic, scalar, growing mode perturbations not only creates acoustic oscillations of the kind observed on very large scales today, it also leads to the production of shocks in the radiation fluid of the very early Universe. Shocks cause departures from local thermal equilibrium as well as create vorticity and gravitational waves. For a scale-invariant spectrum and standard model physics, shocks form for temperatures 1  GeVUniverse as early as 10^{-30}  sec after the big bang.

Neutron-capture nucleosynthesis in the first stars

International Nuclear Information System (INIS)

Roederer, Ian U.; Preston, George W.; Thompson, Ian B.; Shectman, Stephen A.; Sneden, Christopher

2014-01-01

Recent studies suggest that metal-poor stars enhanced in carbon but containing low levels of neutron-capture elements may have been among the first to incorporate the nucleosynthesis products of the first generation of stars. We have observed 16 stars with enhanced carbon or nitrogen using the MIKE Spectrograph on the Magellan Telescopes at Las Campanas Observatory and the Tull Spectrograph on the Smith Telescope at McDonald Observatory. We present radial velocities, stellar parameters, and detailed abundance patterns for these stars. Strontium, yttrium, zirconium, barium, europium, ytterbium, and other heavy elements are detected. In four stars, these heavy elements appear to have originated in some form of r-process nucleosynthesis. In one star, a partial s-process origin is possible. The origin of the heavy elements in the rest of the sample cannot be determined unambiguously. The presence of elements heavier than the iron group offers further evidence that zero-metallicity rapidly rotating massive stars and pair instability supernovae did not contribute substantial amounts of neutron-capture elements to the regions where the stars in our sample formed. If the carbon- or nitrogen-enhanced metal-poor stars with low levels of neutron-capture elements were enriched by products of zero-metallicity supernovae only, then the presence of these heavy elements indicates that at least one form of neutron-capture reaction operated in some of the first stars.

178th International School of Physics "Enrico Fermi" : From the Big Bang to the Nucleosynthesis

CERN Document Server

Nappi, E

2011-01-01

Physicists have devoted much effort to reproducing the conditions of the primordial universe in laboratory conditions in their quest to work out a comprehensive theory of the appearance and evolution of nuclear matter. Whether it be trying to recreate the predicted primordial state of high-energy density matter in which quarks and gluons are effectively deconfined - the so-called Quark Gluon Plasma (QGP) - or exploring the structure and reaction properties of very unstable nuclei in experiments using radioactive beams, they have striven to understand the events which characterized the Big Bang and the various nucleosynthesis mechanisms which occur in the stars. This book contains the proceedings of the 2010 Enrico Fermi summer school held in Varenna, Italy, in July 2010, and devoted to the present understanding of the primordial universe and the origin of the elements, as achieved by studying nuclei and their constituents in extreme regimes of energy and composition. Subjects covered include: QGP formation; e...

Late baryogenesis faces primordial nucleosynthesis

International Nuclear Information System (INIS)

Delbourgo-Salvador, P.; Audouze, J.; Salati, P.

1991-11-01

Since the sphalleron mechanism present in the standard theory of electro-weak interactions violates B+L, models have been suggested where baryogenesis takes place at late epochs and is concomitant with primordial nucleosynthesis. The possibility for the baryon asymmetry to be generated was numerically investigated at the same time as the light elements are cooked. The primordial yields of D, 3 He, 4 He and 7 Li were shown to exceed the upper limits inferred from observation, unless baryogenesis is anterior to the freeze-out of the weak interactions. This implies strong constraints on scenarios where the baryon asymmetry originates from the late decay of massive gravitinos. (author) 18 refs., 6 figs

Big Bang nucleosynthesis in crisis?

International Nuclear Information System (INIS)

Hata, N.; Scherrer, R.J.; Steigman, G.; Thomas, D.; Walker, T.P.; Bludman, S.; Langacker, P.

1995-01-01

A new evaluation of the constraint on the number of light neutrino species (N ν ) from big bang nucleosynthesis suggests a discrepancy between the predicted light element abundances and those inferred from observations, unless the inferred primordial 4 He abundance has been underestimated by 0.014±0.004 (1σ) or less than 10% (95% C.L.) of 3 He survives stellar processing. With the quoted systematic errors in the observed abundances and a conservative chemical evolution parametrization, the best fit to the combined data is N ν =2.1±0.3 (1σ) and the upper limit is N ν ν =3) at the 98.6% C.L. copyright 1995 The American Physical Society

Cosmological nucleosynthesis and active-sterile neutrino oscillations with small mass differences: the nonresonant case

International Nuclear Information System (INIS)

Kirilova, D.P.; Chizhov, M.V.

1998-05-01

We study the nonresonant oscillations between left-handed electron neutrinos ν s and nonthermalized sterile neutrinos ν s in the early Universe plasma. The case when ν s do not thermalize till 2 MeV and the oscillations become effective after ν e decoupling is discussed. As far as for this model the rates of expansion of the Universe, neutrino oscillations and neutrino interactions with the medium may be comparable, we have analyzed the kinetic equations for neutrino density matrix, accounting simultaneously for these processes. The evolution of neutrino ensembles was described numerically by integrating the kinetic equations for the neutrino density matrix in momentum space for small mass differences δm 2 ≤10 -7 eV 2 . This approach allowed us to study precisely the evolution of the neutrino number densities, energy spectrum distortion and the asymmetry between neutrinos and antineutrinos due to oscillations for each momentum mode. We have performed a complete numerical analysis for the full range of the oscillations parameters of the model of the influence of the nonequilibrium ν e ↔ν s oscillations on the primordial production of 4 He. The exact kinetic approach enabled us to calculate the effects of neutrino population depletion, the distortion of the neutrino spectrum and the generation of neutrino-antineutrino asymmetry on the kinetics of neutron-to-proton transitions during the primordial nucleosynthesis epoch and correspondingly on the cosmological 4 He production. It was shown that the neutrino population depletion and spectrum distortion play an important role. The asymmetry effect, in case the lepton asymmetry is accepted initially equal to the baryon one, is proved to be negligible for the discussed range of δm 2 . Constant helium contours in δm 2 -θ plane were calculated. Thanks to the exact kinetic approach more precise cosmological constraints on the mixing parameters were obtained. (author)

Collaborative Research: Neutrinos and Nucleosynthesis in Hot Dense Matter

Energy Technology Data Exchange (ETDEWEB)

McLaughlin, Gail [North Carolina State Univ., Raleigh, NC (United States); Schaefer, Thomas [North Carolina State Univ., Raleigh, NC (United States)

2015-05-31

The major accomplishments of the research activity at NC State during the five years were: to determine the effects and signatures of turbulence in supernova, to calculate r-process and supernova nucleosynthesis, and to determine the neutrino scattering and flavor transformation that occurs in black hole accretion disks. This report goes into more detail on them.

The standard and degenerate primordial nucleosynthesis versus recent experimental data

International Nuclear Information System (INIS)

Esposito, S.; Mangano, G.; Miele, G.; Pisanti, O.

2000-01-01

We report the results on Big Bang Nucleosynthesis (BBN) based on an updated code, with accuracy of the order of 0.1% on He4 abundance, compared with the predictions of other recent similar analysis. We discuss the compatibility of the theoretical results, for vanishing neutrino chemical potentials, with the observational data. Bounds on the number of relativistic neutrinos and baryon abundance are obtained by a likelihood analysis. We also analyze the effect of large neutrino chemical potentials on primordial nucleosynthesis, motivated by the recent results on the Cosmic Microwave Background Radiation spectrum. The BBN exclusion plots for electron neutrino chemical potential and the effective number of relativistic neutrinos are reported. We find that the standard BBN seems to be only marginally in agreement with the recent BOOMERANG and MAXIMA-1 results, while the agreement is much better for degenerate BBN scenarios for large effective number of neutrinos, N ν ∼ 10. (author)

Treatment of isomers in nucleosynthesis codes

Science.gov (United States)

Reifarth, René; Fiebiger, Stefan; Göbel, Kathrin; Heftrich, Tanja; Kausch, Tanja; Köppchen, Christoph; Kurtulgil, Deniz; Langer, Christoph; Thomas, Benedikt; Weigand, Mario

2018-03-01

The decay properties of long-lived excited states (isomers) can have a significant impact on the destruction channels of isotopes under stellar conditions. In sufficiently hot environments, the population of isomers can be altered via thermal excitation or de-excitation. If the corresponding lifetimes are of the same order of magnitude as the typical time scales of the environment, the isomers have to be treated explicitly. We present a general approach to the treatment of isomers in stellar nucleosynthesis codes and discuss a few illustrative examples. The corresponding code is available online at http://exp-astro.de/isomers/.

Sterile neutrinos in the early universe

Energy Technology Data Exchange (ETDEWEB)

Malaney, R.A. (Lawrence Livermore National Lab., CA (USA)); Fuller, G.M. (California Univ., San Diego, La Jolla, CA (USA). Dept. of Physics)

1990-11-14

We discuss the role played by right-handed sterile neutrinos in the early universe. We show how well known {sup 4}He constraint on the number of relativistic degrees of freedom at early times limits the equilibration of the right handed neutrino sea with the background plasma. We discuss how this allows interesting constraints to be placed on neutrino properties. In particular, a new limit on the Dirac mass of the neutrino is presented. 12 refs.

Some effects of high temperature and density on neutron-capture nucleosynthesis

International Nuclear Information System (INIS)

Norman, E.B.; Kellogg, S.E.

1984-01-01

Examples of nuclear reactions between nuclei in excited states, beta decays of nuclear excited states, and bound-state beta decays are shown. The effects of these processes on selected problems in heavy-element nucleosynthesis are discussed. 40 references

The Main Path to C, N, O Elements in Big Bang Nucleosynthesis

International Nuclear Information System (INIS)

Su-Qing, Hou; Kai-Su, Wu; Yong-Shou, Chen; Neng-Chuan, Shu; Zhi-Hong, Li

2010-01-01

The production of C, N, O elements in a standard big bang nucleosynthesis scenario is investigated. Using the up-to-date data of nuclear reactions in BBN, in particular the 8 Li (n,γ) 9 Li which has been measured in China Institute of Atomic Energy, a full nucleosynthesis network calculation of BBN is carried out. Our calculation results show that the abundance of 12 C is increased for an order of magnitude after addition of the reaction chain 8 Li(n,γ) 9 Li(α,n) 12 B(β) 12 C, which was neglected in previous studies. We find that this sequence provides the main channel to convert the light elements into C, N, O in standard BBN. (nuclear physics)

Radionuclides 26Al, 53Mn and 60Fe as a test of the possible nucleosynthesis immediately before solar system formation

International Nuclear Information System (INIS)

Chechev, V.P.

2000-01-01

Parameters of a possible burst of nucleosynthesis just prior to the solar system formation were calculated on the basis of data on occurrence of 26 Al, 53 Mn and 60 Fe radionuclides in the early solar system. The whole number of the observance data was shown to result in the following restrictions of the parameters of the mentioned burst: its contribution into the general galactic synthesis of the elements did not exceed 0.5 % while time interval from the burst up to hardening of meteorites did not exceed 10 mln. years [ru

The early period of the universal Fermi interaction

International Nuclear Information System (INIS)

Tiomno, J.

1984-01-01

A critical analysis of the contributions which lead, in the early period, to the discovery of the universality of Fermi-type weak interactions is made. In particular the current references to this universality as 'Puppi's triangle' are shown to be incorrect. (Author) [pt

The Early Universe. Facts and fiction. 4. ed.

International Nuclear Information System (INIS)

Boerner, G.

2003-01-01

The following topics are covered in this completely new written textbook: The standard big bang model, thermodynamics of the Early universe, gauge theories and standard model, grand unification models, baryon synthesis, inflationary universe, dark matter and galaxy formation, evolution of small perturbations, non-linear structure formation (WL)

Big Bang nucleosynthesis: The standard model

International Nuclear Information System (INIS)

Steigman, G.

1989-01-01

Current observational data on the abundances of deuterium, helium-3, helium-4 and lithium-7 are reviewed and these data are used to infer (or to bound) the primordial abundances of these elements. The physics of primordial nucleosynthesis in the context of the ''standard'' (isotropic, homogeneous,...) hot big bang model is outlined and the primordial abundances predicted within the context of this model are presented. The theoretical predictions are then confronted with the observational data. This confrontation reveals the remarkable consistency of the standard model, constrains the nucleon abundance to lie within a narrow range and, permits the existence of no more than one additional flavor of light neutrinos

Quantum cosmology and the early universe

International Nuclear Information System (INIS)

Hartle, J.B.

1983-01-01

Despite the absence of a complete and manageable quantum theory of gravity, it is shown that considerable progress has been made in constructing cosmological models displaying the possible implications such a theory might have for the structure and dynamics of the very early universe. (U.K.)

arXiv AlterBBN v2: A public code for calculating Big-Bang nucleosynthesis constraints in alternative cosmologies

CERN Document Server

Arbey, A.; Hickerson, K.P.; Jenssen, E.S.

We present the version 2 of AlterBBN, an open public code for the calculation of the abundance of the elements from Big-Bang nucleosynthesis. It does not rely on any closed external library or program, aims at being user-friendly and allowing easy modifications, and provides a fast and reliable calculation of the Big-Bang nucleosynthesis constraints in the standard and alternative cosmologies.

Nucleosynthesis of heavy elements by the photonuclear reaction

International Nuclear Information System (INIS)

Hayakawa, Takehito

2002-01-01

Nucleosynthesis of heavy elements is important for understanding of the site mechanism in the stellar and cosmochronology. The nuclei heavier than iron have been synthesized mainly by the s-process and the β-decay after the r-process. The light isotope p-nuclei produced by the photonuclear reaction in Type II supernovae explosions. In order to understand the role of each process, the ratios of the processes are calculated. I propose the experimental plan using the photon sources. (author)

Bulk viscous cosmology in early Universe

Indian Academy of Sciences (India)

The effect of bulk viscosity on the early evolution of Universe for a spatially homogeneous and isotropic Robertson-Walker model is considered. Einstein's field equations are solved by using `gamma-law' equation of state = ( - 1)ρ, where the adiabatic parameter gamma () depends on the scale factor of the model.

Accelerated expansion of a universe containing a self-interacting Bose-Einstein gas

Energy Technology Data Exchange (ETDEWEB)

Izquierdo, German; Besprosvany, Jaime, E-mail: german.izquierdo@gmail.co, E-mail: bespro@fisica.unam.m [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Circuito de la Investigacion CientIfica S/N, Ciudad Universitaria, CP 04510, Mexico, Distrito Federal (Mexico)

2010-03-21

Acceleration of the universe is obtained from a model of non-relativistic particles with a short-range attractive interaction, at low enough temperature to produce a Bose-Einstein condensate. Conditions are derived for negative-pressure behavior. In particular, we show that a phantom-accelerated regime at the beginning of the universe solves the horizon problem, consistently with nucleosynthesis.

Protostar formation in the early universe.

Science.gov (United States)

Yoshida, Naoki; Omukai, Kazuyuki; Hernquist, Lars

2008-08-01

The nature of the first generation of stars in the universe remains largely unknown. Observations imply the existence of massive primordial stars early in the history of the universe, and the standard theory for the growth of cosmic structure predicts that structures grow hierarchically through gravitational instability. We have developed an ab initio computer simulation of the formation of primordial stars that follows the relevant atomic and molecular processes in a primordial gas in an expanding universe. The results show that primeval density fluctuations left over from the Big Bang can drive the formation of a tiny protostar with a mass 1% that of the Sun. The protostar is a seed for the subsequent formation of a massive primordial star.

Deep Mixing of 3He: Reconciling Big Bang and Stellar Nucleosynthesis

International Nuclear Information System (INIS)

Eggleton, P P; Dearborn, D P; Lattanzio, J

2006-01-01

Low-mass stars, ∼ 1-2 solar masses, near the Main Sequence are efficient at producing 3 He, which they mix into the convective envelope on the giant branch and should distribute into the Galaxy by way of envelope loss. This process is so efficient that it is difficult to reconcile the low observed cosmic abundance of 3 He with the predictions of both stellar and Big Bang nucleosynthesis. In this paper we find, by modeling a red giant with a fully three-dimensional hydrodynamic code and a full nucleosynthetic network, that mixing arises in the supposedly stable and radiative zone between the hydrogen-burning shell and the base of the convective envelope. This mixing is due to Rayleigh-Taylor instability within a zone just above the hydrogen-burning shell, where a nuclear reaction lowers the mean molecular weight slightly. Thus we are able to remove the threat that 3 He production in low-mass stars poses to the Big Bang nucleosynthesis of 3 He

Deep mixing of 3He: reconciling Big Bang and stellar nucleosynthesis.

Science.gov (United States)

Eggleton, Peter P; Dearborn, David S P; Lattanzio, John C

2006-12-08

Low-mass stars, approximately 1 to 2 solar masses, near the Main Sequence are efficient at producing the helium isotope 3He, which they mix into the convective envelope on the giant branch and should distribute into the Galaxy by way of envelope loss. This process is so efficient that it is difficult to reconcile the low observed cosmic abundance of 3He with the predictions of both stellar and Big Bang nucleosynthesis. Here we find, by modeling a red giant with a fully three-dimensional hydrodynamic code and a full nucleosynthetic network, that mixing arises in the supposedly stable and radiative zone between the hydrogen-burning shell and the base of the convective envelope. This mixing is due to Rayleigh-Taylor instability within a zone just above the hydrogen-burning shell, where a nuclear reaction lowers the mean molecular weight slightly. Thus, we are able to remove the threat that 3He production in low-mass stars poses to the Big Bang nucleosynthesis of 3He.

Big bang nucleosynthesis: The strong nuclear force meets the weak anthropic principle

International Nuclear Information System (INIS)

MacDonald, J.; Mullan, D. J.

2009-01-01

Contrary to a common argument that a small increase in the strength of the strong force would lead to destruction of all hydrogen in the big bang due to binding of the diproton and the dineutron with a catastrophic impact on life as we know it, we show that provided the increase in strong force coupling constant is less than about 50% substantial amounts of hydrogen remain. The reason is that an increase in strong force strength leads to tighter binding of the deuteron, permitting nucleosynthesis to occur earlier in the big bang at higher temperature than in the standard big bang. Photodestruction of the less tightly bound diproton and dineutron delays their production to after the bulk of nucleosynthesis is complete. The decay of the diproton can, however, lead to relatively large abundances of deuterium.

Early Predictors of First-Year Academic Success at University: Pre-University Effort, Pre-University Self-Efficacy, and Pre-University Reasons for Attending University

Science.gov (United States)

van Herpen, Sanne G. A.; Meeuwisse, Marieke; Hofman, W. H. Adriaan; Severiens, Sabine E.; Arends, Lidia R.

2017-01-01

Given the large number of dropouts in the 1st year at university, it is important to identify early predictors of 1st-year academic success. The present study (n = 453 first-year students) contributes to literature on the transition from secondary to higher education by investigating how the non-cognitive factors "pre-university" effort…

Neutrino oscillations in the early universe

International Nuclear Information System (INIS)

Enqvist, K.

1990-01-01

The oscillations of electron neutrinos into inert neutrinos may have resonant behaviour in the heat bath of the early Universe. It is shown that any initial neutrino asymmetry will be washed away by the oscillations. Neutrino oscillations would affect also primordial helium production, which implies stringent limits on the neutrino mixing parameters. (orig.)

Formation of structures in the very early universe

International Nuclear Information System (INIS)

Bertolami Neto, O.; Marques, G.C.; Ventura, I.

1984-01-01

An alternative picture of cosmological phase transition is sketched and its implications to the formation of structures in the very early Universe is studied. It is shown that the condensation of walls at high temperatures leads to fluctuations which are in accordance to all necessary conditions to the formation of structures in the Universe. Furthermore the number of aglutination centers is roughly equal to the numbers of great structures observed in the Universe today. (Author) [pt

Supersymmetry in the very early universe

International Nuclear Information System (INIS)

Thomas, S.

1995-06-01

Supersymmetric flat directions can have a number of important consequences in the very early universe. Depending on the form of the SUSY breaking potential arising from the finite energy density at early times, coherent production of scalar condensates can result along such directions. This leads a cosmological disaster for Polonyi type flat directions with only Planck suppressed couplings, but can give rise to the baryon asymmetry for standard model flat directions. Flat directions are also natural candidates to act as inflatons. Achieving density fluctuations of the correct magnitude generally requires an additional hidden SUSY breaking sector

Gravitino Condensates in the Early Universe and Inflation

CERN Document Server

Mavromatos, Nick E

2015-01-01

We review work on the formation of gravitino condensates via the super-Higgs effect in the early Universe. This is a scenario for both inflating the early universe and breaking local supersymmetry (supergravity), entirely independent of any coupling to external matter. The goldstino mode associated with the breaking of (global) supersymmetry is "eaten" by the gravitino field, which becomes massive (via its own vacuum condensation) and breaks the local supersymmetry (supergravity) dynamically. The most natural association of gravitino condensates with inflation proceeds in an indirect way, via a Starobinsky-inflation-type phase. The higher-order curvature corrections of the (quantum) effective action of gravitino condensates induced by integrating out massive gravitino degrees of freedom in a curved space-time background, in the broken-supergravity phase, are responsible for inducing a scalar mode which inflates the Universe. The scenario is in agreement with Planck data phenomenology in a natural and phenomen...

Magnetic Fields in the Early Universe

CERN Document Server

Grasso, D; Grasso, D

2001-01-01

This review concerns the origin and the possible effects of magnetic fields in the early Universe. We start by providing to the reader with a short overview of the current state of art of observations of cosmic magnetic fields. We then illustrate the arguments in favour of a primordial origin of magnetic fields in the galaxies and in the clusters of galaxies. We argue that the most promising way to test this hypothesis is to look for possible imprints of magnetic fields on the temperature and polarization anisotropies of the cosmic microwave background radiation (CMBR). With this purpose in mind, we provide a review of the most relevant effects of magnetic fields on the CMBR. A long chapter of this review is dedicated to particle physics inspired models which predict the generation of magnetic fields during the early Universe evolution. Although it is still unclear if any of these models can really explain the origin of galactic and intergalactic magnetic fields, we show that interesting effects may arise any...

The role of nuclear inputs in r-process nucleosynthesis

Energy Technology Data Exchange (ETDEWEB)

Giuliani, Samuel Andrea; Arzhanov, Alexander; Friess, Stephen; Martinez-Pinedo, Gabriel; Moeller, Heiko; Sieverding, Andre; Wu, Meng-Ru [TU Darmstadt (Germany)

2016-07-01

We have studied the sensitivity of the r-process abundances produced in dynamical ejecta from neutron star mergers to different nuclear mass models. For each mass model, the resulting abundances are almost independent of the astrophysical conditions and reproduce the general features of the observed r-process abundance. We find that the second peak around A ∝ 130 is produced by the fission yields of the material that piles up in nuclei with A >or similar 250. We also find distinct differences in the predictions at and just above the third peak (A ∝ 195) for different mass models, due to different neutron separation energies at N = 130. Due to the crucial role that fission plays in r-process nucleosynthesis, we have computed the fission properties of superheavy nuclei using the BCPM energy density functional. We found that certain combinations of neutron and proton number lead to an enhanced stability against the spontaneous fission process, related with the existence of magic numbers in the superheavy region. However, the systematic of the fission properties is strongly affected by the choice of the collective degree of freedom when the fission path is obtained by minimizing the action integral. Finally, a comparison with other theoretical models and the consequences for r-process nucleosynthesis are discussed.

IMPACT OF NEW GAMOW–TELLER STRENGTHS ON EXPLOSIVE TYPE IA SUPERNOVA NUCLEOSYNTHESIS

Energy Technology Data Exchange (ETDEWEB)

Mori, Kanji; Famiano, Michael A.; Kajino, Toshitaka; Suzuki, Toshio [National Astronomical Observatory of Japan 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Hidaka, Jun [Mechanical Engineering Department, Meisei University, 2-1-1 Hodokubo, Hino, Tokyo 191-8506 (Japan); Honma, Michio [Center for Mathematical Sciences, University of Aizu, Aizu-Wakamatsu, Fukushima 965-8580 (Japan); Iwamoto, Koichi [Department of Physics, College of Science and Technology, Nihon University, Tokyo 101-8308 (Japan); Nomoto, Ken’ichi [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan); Otsuka, Takaharu, E-mail: kanji.mori@nao.ac.jp, E-mail: kajino@nao.ac.jp, E-mail: michael.famiano@wmich.edu, E-mail: suzuki@phys.chs.nihon-u.ac.jp, E-mail: jun.hidaka@meisei-u.ac.jp, E-mail: m-honma@u-aizu.ac.jp, E-mail: iwamoto@phys.cst.nihon-u.ac.jp, E-mail: nomoto@astron.s.u-tokyo.ac.jp, E-mail: otsuka@phys.s.u-tokyo.ac.jp [Department of Physics, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

2016-12-20

Recent experimental results have confirmed a possible reduction in the Gamow–Teller (GT{sub +}) strengths of pf-shell nuclei. These proton-rich nuclei are of relevance in the deflagration and explosive burning phases of SNe Ia. While prior GT strengths result in nucleosynthesis predictions with a lower-than-expected electron fraction, a reduction in the GT{sub +} strength can result in a slightly increased electron fraction compared to previous shell model predictions, though the enhancement is not as large as previous enhancements in going from rates computed by Fuller, Fowler, and Newman based on an independent particle model. A shell model parametrization has been developed that more closely matches experimental GT strengths. The resultant electron-capture rates are used in nucleosynthesis calculations for carbon deflagration and explosion phases of SNe Ia, and the final mass fractions are compared to those obtained using more commonly used rates.

Quark mass variation constraints from Big Bang nucleosynthesis

International Nuclear Information System (INIS)

Bedaque, Paulo F.; Luu, Thomas; Platter, Lucas

2011-01-01

We study the impact on the primordial abundances of light elements created by a variation of the quark masses at the time of Big Bang nucleosynthesis (BBN). In order to navigate through the particle and nuclear physics required to connect quark masses to binding energies and reaction rates in a model-independent way, we use lattice QCD data and a hierarchy of effective field theories. We find that the measured 4 He abundances put a bound of -1% q /m q q /m q .

The gravitino-stau scenario after catalyzed big bang nucleosynthesis

Science.gov (United States)

Kersten, Jörn; Schmidt-Hoberg, Kai

2008-01-01

We consider the impact of catalyzed big bang nucleosynthesis on theories with a gravitino lightest superparticle and a charged slepton next-to-lightest superparticle. In models where the gravitino to gaugino mass ratio is bounded from below, such as gaugino-mediated supersymmetry breaking, we derive a lower bound on the gaugino mass parameter m1/2. As a concrete example, we determine the parameter space of gaugino mediation that is compatible with all cosmological constraints.

The gravitino–stau scenario after catalyzed big bang nucleosynthesis

International Nuclear Information System (INIS)

Kersten, Jörn; Schmidt-Hoberg, Kai

2008-01-01

We consider the impact of catalyzed big bang nucleosynthesis on theories with a gravitino lightest superparticle and a charged slepton next-to-lightest superparticle. In models where the gravitino to gaugino mass ratio is bounded from below, such as gaugino-mediated supersymmetry breaking, we derive a lower bound on the gaugino mass parameter m 1/2 . As a concrete example, we determine the parameter space of gaugino mediation that is compatible with all cosmological constraints

Chemical evolution, stellar nucleosynthesis and a variable star formation rate

International Nuclear Information System (INIS)

Olive, K.A.; Thielemann, F.K.; Truran, J.W.

1986-04-01

The effects of a decreasing star formation rate (SFR) on the galactic abundances of elements produced in massive stars (M ≥ 10 Msub solar). On the basis of a straightforward model of galactic evolution, a relation between the upper mass limit of type II supernovae (M/sub SN/) contributing to chemical evolution and the decline of the SFR (tau) is derived, when the oxygen abundance is determined only by massive stars. The additional requirement that all intermediate mass elements (Ne-Ti), which are also predominantly due to nucleosynthesis in massive stars, are produced in solar proportions leads to a unique value of M/sub SN/ and tau. The application of this method with abundance yields from Arnett (1978) and Woosley and Weaver (1986) resuults, however, in contradicting solutions: M/sub SN/ ≅ 45 Msub solar, tau = ∞, and M/sub SN/ ≅ 15 Msub solar, tau = 3 x 10 9 y. Thus, in order that this approach provide an effective probe of the SFR over the history of our galaxy it is essential that converging and more accurate predictions of the consequences of stellar and supernova nucleosynthesis will be forthcoming. 54 refs., 2 figs., 2 tabs

Abundances of La and Ta Through ν-Nucleosynthesis in 20M ...

Indian Academy of Sciences (India)

Solar mass fractions of the seeds La139, Ta181, Ba138 and Hf180 are taken for calculation. They are assumed to be produced in ... of these elements by extending the earlier works on neutrino nucleosynthesis in massive stars. .... ing the shock heating of the layers surrounding the collapsing core of supernova progenitor.

The Transient High Energy Sky and Early Universe Surveyor

Science.gov (United States)

O'Brien, P. T.

2016-04-01

The Transient High Energy Sky and Early Universe Surveyor is a mission which will be proposed for the ESA M5 call. THESEUS will address multiple components in the Early Universe ESA Cosmic Vision theme:4.1 Early Universe,4.2 The Universe taking shape, and4.3 The evolving violent Universe.THESEUS aims at vastly increasing the discovery space of the high energy transient phenomena over the entire cosmic history. This is achieved via a unique payload providing an unprecedented combination of: (i) wide and deep sky monitoring in a broad energy band(0.3 keV-20 MeV; (ii) focusing capabilities in the soft X-ray band granting large grasp and high angular resolution; and (iii) on board near-IR capabilities for immediate transient identification and first redshift estimate.The THESEUS payload consists of: (i) the Soft X--ray Imager (SXI), a set of Lobster Eye (0.3--6 keV) telescopes with CCD detectors covering a total FOV of 1 sr; (ii) the X--Gamma-rays spectrometer (XGS), a non-imaging spectrometer (XGS) based on SDD+CsI, covering the same FOV than the Lobster telescope extending the THESEUS energy band up to 20 MeV; and (iii) a 70cm class InfraRed Telescope (IRT) observing up to 2 microns with imaging and moderate spectral capabilities.The main scientific goals of THESEUS are to:(a) Explore the Early Universe (cosmic dawn and reionization era) by unveiling the Gamma--Ray Burst (GRBs) population in the first billion years}, determining when did the first stars form, and investigating the re-ionization epoch, the interstellar medium (ISM) and the intergalactic medium (IGM) at high redshifts.(b) Perform an unprecedented deep survey of the soft X-ray transient Universe in order to fill the present gap in the discovery space of new classes of transient; provide a fundamental step forward in the comprehension of the physics of various classes of Galactic and extra--Galactic transients, and provide real time trigger and accurate locations of transients for follow-up with next

Chiral-symmetry order parameter, the lattice, and nucleosynthesis

International Nuclear Information System (INIS)

McLerran, L.

1987-01-01

I discuss an order parameter for the chiral-symmetry restoration phase transition which may be useful in computations of big-bang nucleosynthesis, a phenomenon which requires a finite baryon-number density. This parameter is strictly speaking an order parameter in the large-N limit, and distinguishes between a parity-doubled and a massless-fermion realization of chiral-symmetry restoration. This order parameter may be evaluated at a zero net baryon-number density at finite temperature, and is useful as long as the baryon chemical potential μ is much less than the temperature T

Dynamics of stringy congruence in the early universe

International Nuclear Information System (INIS)

Cho, Yong Seung; Hong, Soon-Tae

2011-01-01

We study twist and shear aspects of the stingy geodesic surface congruence. Under some natural conditions we derive the equations of the twist and shear in terms of the expansion of the Universe. We observe in this higher dimensional cosmology that, as the early universe evolves with expansion rate, the twist of the stringy congruence decreases exponentially and the initial twist value should be large enough to sustain the rotations of the ensuing universe, while the effects of the shear are negligible to produce the isotropic and homogeneous universe. We also investigate the twist and shear of the geodesic surface congruence of the null strings.

Can Planck-mass relics of evaporating black holes close the Universe

International Nuclear Information System (INIS)

MacGibbon, J.H.

1987-01-01

The authors propose that the cosmological dark matter consists of the Planck-mass remnants of evaporating primordial black holes. Such remnants would be expected to have close to the critical density if the black holes evaporating at the present epoch have the maximum density consistent with cosmic-ray constraints. Primordial black holes of the required density may form naturally at the end of an inflationary epoch. Planck-mass relics would behave dynamically just like 'cold dark matter' and would therefore share the attractions of other 'cold' candidates. In addition, because the baryonic matter in black holes cannot participate in nucleosynthesis the limits on the baryonic content of the Universe set by primordial nucleosynthesis are circumvented. (author)

Dual QCD and phase transition in early universe

International Nuclear Information System (INIS)

Ranjan, Akhilesh; Raina, P.K.; Nandan, Hemwati

2009-01-01

The quantum chromodynamics (QCD) vacuum with condensed monopoles/ dyons (i.e., a dual Ginzburg- Landau (DGL) type model of QCD or dual QCD) has been quite successful to describe the large-distance behavior of QCD vacuum. Further, such DGL theory of QCD at finite temperature is also found to be useful in studying the phase transition process as believed to occur in early universe. In the present article, we have used the DGL theory of QCD with dyons to study the hadronisation in early universe. The effective potential at finite temperature is calculated. The notions of the phase transition in the background of the dyonically condensed QCD vacuum has been investigated by calculating the critical temperature in view of the temperature dependent couplings

Phenomenology of a realistic accelerating universe using tracker fields

Indian Academy of Sciences (India)

We present a realistic scenario of tracking of scalar fields with varying equation of state. The astrophysical constraints on the evolution of scalar fields in the physical universe are discussed. The nucleosynthesis and the galaxy formation constraints have been used to put limits on and estimate during cosmic evolution.

The gravitino-stau scenario after catalyzed big bang nucleosynthesis

Energy Technology Data Exchange (ETDEWEB)

Kersten, Joern [The Abdus Salam ICTP, Strada Costiera 11, 34014 Trieste (Italy); Schmidt-Hoberg, Kai, E-mail: jkersten@ictp.it, E-mail: kai.schmidt-hoberg@ph.tum.de, E-mail: kai.schmidt.hoberg@desy.de [Physik-Department T30, Technische Universitaet Muenchen, James-Franck-Strasse, 85748 Garching (Germany)

2008-01-15

We consider the impact of catalyzed big bang nucleosynthesis on theories with a gravitino lightest superparticle and a charged slepton next-to-lightest superparticle. In models where the gravitino to gaugino mass ratio is bounded from below, such as gaugino-mediated supersymmetry breaking, we derive a lower bound on the gaugino mass parameter m{sub 1/2}. As a concrete example, we determine the parameter space of gaugino mediation that is compatible with all cosmological constraints.

High-entropy ejections from magnetized proto-neutron star winds: implications for heavy element nucleosynthesis

Science.gov (United States)

Thompson, Todd A.; ud-Doula, Asif

2018-06-01

Although initially thought to be promising for production of the r-process nuclei, standard models of neutrino-heated winds from proto-neutron stars (PNSs) do not reach the requisite neutron-to-seed ratio for production of the lanthanides and actinides. However, the abundance distribution created by the r-, rp-, or νp-processes in PNS winds depends sensitively on the entropy and dynamical expansion time-scale of the flow, which may be strongly affected by high magnetic fields. Here, we present results from magnetohydrodynamic simulations of non-rotating neutrino-heated PNS winds with strong dipole magnetic fields from 1014 to 1016 G, and assess their role in altering the conditions for nucleosynthesis. The strong field forms a closed zone and helmet streamer configuration at the equator, with episodic dynamical mass ejections in toroidal plasmoids. We find dramatically enhanced entropy in these regions and conditions favourable for third-peak r-process nucleosynthesis if the wind is neutron-rich. If instead the wind is proton-rich, the conditions will affect the abundances from the νp-process. We quantify the distribution of ejected matter in entropy and dynamical expansion time-scale, and the critical magnetic field strength required to affect the entropy. For B ≳1015 G, we find that ≳10-6 M⊙ and up to ˜10-5 M⊙ of high-entropy material is ejected per highly magnetized neutron star birth in the wind phase, providing a mechanism for prompt heavy element enrichment of the universe. Former binary companions identified within (magnetar-hosting) supernova remnants, the remnants themselves, and runaway stars may exhibit overabundances. We provide a comparison with a semi-analytic model of plasmoid eruption and discuss implications and extensions.

Nucleosynthesis in Wolf-Rayet stars and galactic cosmic-ray isotopic composition

International Nuclear Information System (INIS)

Prantzos, N.

1984-01-01

An explanation of the isotopic composition of galactic cosmic rays could provide some clues to the mystery of their origin. It seems now that the strong stellar winds of Wolf-Rayet stars could account for most of the isotopic anomalies that have been observed in cosmic rays. Some results are presented, obtained by detailed nucleosynthesis computations. 25 references

The Physics of the Early Universe

International Nuclear Information System (INIS)

Scott, Douglas

2007-01-01

The physics of the very small and the very large were successfully brought together in the 1980s through the idea of 'the universe as a particle accelerator'. The manifesto of this new campaign was laid out in the book 'The Early Universe' by Kolb and Turner in 1990. For at least the next decade that book was to be found on the shelves of every theorist (and many experimentalists) who professed an interest in this topic. But science marches on, and the last 10-15 years has seen an explosion in our understanding of the physics of the very earliest times and the very largest scales. Experimentally our world-view has changed utterly, through exquisitely precise measurements of the cosmic microwave background, galaxy clustering and supernova distances, with a refinement of the basic inflationary big bang paradigm into the new 'standard cosmological model'. And in tandem with these changes has been the development of new theoretical ideas, particularly involving dark energy and connections between string/brane theory and cosmology. So what is the new book for the shelves of today's cohort of young Rockys and Mikes? Despite a recent number of promising-sounding cosmology books, there is nothing at the advanced level which is broad enough to be a general introduction to the 'early universe' topic. Perhaps the best of the bunch is 'The Physics of the Early Universe', edited by E Papantonopoulos as part of Springer's series 'Lecture notes in physics'. This is a set of 9 review articles given as part of a 2003 summer school on Syros Island, Greece. Although far from perfect, the core of this book provides a solid introduction to current research in early universe physics, which should be useful for PhD students or postdoctoral researchers who want the real thing. The book starts with a competent introduction by Kyriakos Tamvakis, serving essentially as a summary of where we were in Kolb and Turner's text. We have learned since then, however, that inflation is really all

Probing Models of Dark Matter and the Early Universe

Science.gov (United States)

Orlofsky, Nicholas David

This thesis discusses models for dark matter (DM) and their behavior in the early universe. An important question is how phenomenological probes can directly search for signals of DM today. Another topic of investigation is how the DM and other processes in the early universe must evolve. Then, astrophysical bounds on early universe dynamics can constrain DM. We will consider these questions in the context of three classes of DM models--weakly interacting massive particles (WIMPs), axions, and primordial black holes (PBHs). Starting with WIMPs, we consider models where the DM is charged under the electroweak gauge group of the Standard Model. Such WIMPs, if generated by a thermal cosmological history, are constrained by direct detection experiments. To avoid present or near-future bounds, the WIMP model or cosmological history must be altered in some way. This may be accomplished by the inclusion of new states that coannihilate with the WIMP or a period of non-thermal evolution in the early universe. Future experiments are likely to probe some of these altered scenarios, and a non-observation would require a high degree of tuning in some of the model parameters in these scenarios. Next, axions, as light pseudo-Nambu-Goldstone bosons, are susceptible to quantum fluctuations in the early universe that lead to isocurvature perturbations, which are constrained by observations of the cosmic microwave background (CMB). We ask what it would take to allow axion models in the face of these strong CMB bounds. We revisit models where inflationary dynamics modify the axion potential and discuss how isocurvature bounds can be relaxed, elucidating the difficulties in these constructions. Avoiding disruption of inflationary dynamics provides important limits on the parameter space. Finally, PBHs have received interest in part due to observations by LIGO of merging black hole binaries. We ask how these PBHs could arise through inflationary models and investigate the opportunity

Study of the 2H(p,γ)3He reaction in the Big Bang Nucleosynthesis energy range at LUNA

Science.gov (United States)

Mossa, Viviana

2018-01-01

Deuterium is the first nucleus produced in the Universe, whose accumulation marks the beginning of the so called Big Bang Nucleosynthesis (BBN). Its primordial abundance is very sensitive to some cosmological parameters like the baryon density and the number of the neutrino families. Presently the main obstacle to an accurate theoretical deuterium abundance evaluation is due to the poor knowledge of the 2H(p,γ)3He cross section at BBN energies. The aim of the present work is to describe the experimental approach proposed by the LUNA collaboration, whose goal is to measure, with unprecedented precision, the total and the differential cross section of the reaction in the 30 < Ec.m. [keV] < 300 energy range.

Early Tracking or Finally Leaving? Determinants of Early Study Success in First-Year University Students

Science.gov (United States)

Brouwer, Jasperina; Jansen, Ellen; Hofman, Adriaan; Flache, Andreas

2016-01-01

Two theoretical approaches underlie this investigation of the determinants of early study success among first-year university students. Specifically, to extend Walberg's educational productivity model, this study draws on the expectancy-value theory of achievement motivation in a contemporary university context. The survey data came from 407…

Big-Bang nucleosynthesis and lithium abundance

International Nuclear Information System (INIS)

Singh, Vinay; Lahiri, Joydev; Bhowmick, Debasis; Basu, D.N.

2017-01-01

The predictions of the standard big-bang nucleosynthesis (BBN) theory depend on the astrophysical nuclear reaction rates and on additional three parameters, the number of flavours of light neutrinos, the neutron lifetime and the baryon-to-photon ratio in the uni- verse. The effect of the modification of thirty-five reaction rates on light element abundance yields in BBN was investigated earlier by us. In the present work we have replaced the neutron lifetime, baryon-to-photon ratio by the most recent values and further modified 3 He( 4 He,γ) 7 Be reaction rate which is used directly for estimating the formation of 7 Li as a result of β + decay by the most recent equation. We find that these modifications reduce the calculated abundance of 7 Li by ∼ 12%

What's Next for Big Bang Nucleosynthesis?

International Nuclear Information System (INIS)

Cyburt, R.H.

2005-01-01

Big bang nucleosynthesis (BBN) plays an important role in the standard hot big bang cosmology. BBN theory is used to predict the primordial abundances of the lightest elements, hydrogen, helium and lithium. Comparison between the predicted and observationally determined light element abundances provides a general test of concordance and can be used to fix the baryon content in the universe. Measurements of the cosmic microwave background (CMB) anisotropies now supplant BBN as the premier baryometer, especially with the latest results from the WMAP satellite. With the WMAP baryon density, the test of concordance can be made even more precise. Any disagreement between theory predictions and observations requires careful discussion. Several possibilities exist to explain discrepancies; (1) observational systematics (either physical or technical) may not be properly treated in determining primordial light element abundances (2) nuclear inputs that determine the BBN predictions may have unknown systematics or may be incomplete, and (3) physics beyond that included in the standard BBN scenario may need to be included in the theory calculation. Before we can be absolutely sure new physics is warranted, points (1) and (2) must be addressed and ruled out. All of these scenarios rely on experimental or observational data to make definitive statements of their applicability and range of validity, which currently is not at the level necessary to discern between these possibilities with high confidence. Thus, new light element abundance observations and nuclear experiments are needed to probe these further. Assuming concordance is established, one can use the light element observations to explore the evolution from their primordial values. This can provide useful information on stellar evolution, cosmic rays and other nuclear astrophysics. When combined with detailed models, BBN, the CMB anisotropy and nuclear astrophysics can provide us with information about the populations

Addendum to 'Update on neutrino mixing in the early universe'

International Nuclear Information System (INIS)

Di Bari, P.

2003-01-01

In the light of the recent WMAP results we update the constraints on a class of nonstandard big bang nucleosynthesis (BBN) models with a simultaneous combination of nonstandard neutrino distributions and an extra effective number of neutrinos in the expansion rate. These models can be described in terms of the two parameters ΔN ν tot , constrained by the primordial helium abundance Y p measurement, and ΔN ν ρ , constrained by a combination of cosmic microwave background and primordial deuterium data. Small deviations from standard big bang nucleosynthesis are suggested. Different nonstandard scenarios can be distinguished by a measurement of the difference ΔN ν f ν =ΔN ν tot -ΔN ν ρ . From the current data we estimate ΔN ν f ν ≅-1.4 -1.4 +0.9 , mildly disfavoring solutions with a low expansion rate, characterized by ΔN ν f ν =0 and negative ΔN ν ρ . Active-sterile neutrino mixing could be a viable explanation only for high values of Y p > or approx. 0.24. The existence of large positive neutrino chemical potentials ξ i ∼0.05, implying ΔN ν ρ ≅0, would be a possible explanation of the data within the analyzed class of nonstandard BBN models. Interestingly, it would also provide a way to evade the cosmological bounds for ''class A 3+1'' four neutrino mixing models. A scenario with a decaying sterile neutrino is also considered

Nucleosynthesis in Jets from Collapsars

International Nuclear Information System (INIS)

Fujimoto, Shin-ichiro; Nishimura, Nobuya; Hashimoto, Masa-aki

2008-01-01

We investigate nucleosynthesis inside magnetically driven jets ejected from collapsars, or rotating magnetized stars collapsing to a black hole, based on two-dimensional magnetohydrodynamic simulation of the collapsars during the core collapse. We follow the evolution of the abundances of about 4000 nuclides from the collapse phase to the ejection phase using a large nuclear reaction network. We find that the r-process successfully operates only in the energetic jets (>10 51 erg), so that U and Th are synthesized abundantly, even when the collapsars have a relatively small magnetic field (10 10 G) and a moderately rotating core before the collapse. The abundance patterns inside the jets are similar to that of the r-elements in the solar system. The higher energy jets have larger amounts of 56 Ni. Less energetic jets, which have small amounts of 56 Ni, could induce GRB without supernova, such as GRB060505 and GRB060614

Deuterium and big bang nucleosynthesis

International Nuclear Information System (INIS)

Burles, S.

2000-01-01

Measurements of deuterium absorption in high redshift quasar absorption systems provide a direct inference of the deuterium abundance produced by big bang nucleosynthesis (BBN). With measurements and limits from five independent absorption systems, we place strong constraints on the primordial ratio of deuterium to hydrogen, (D/H) p = 3.4 ± 0.3 x 10 -5 [1,2]. We employ a direct numerical treatment to improve the estimates of critical reaction rates and reduce the uncertainties in BBN predictions of D/H and 7 Li/H by a factor of three[3] over previous efforts[4]. Using our measurements of (D/H) p and new BBN predictions, we find at 95% confidence the baryon density ρ b = (3.6 ± 0.4) x 10 -31 g cm -3 (Ω b h 2 65 = 0.045 ± 0.006 in units of the critical density), and cosmological baryon-photon ratio η = (5.1 ± 0.6) x 10 -10

Neutrino nucleosynthesis in supernovae: Shell model predictions

International Nuclear Information System (INIS)

Haxton, W.C.

1989-01-01

Almost all of the 3 · 10 53 ergs liberated in a core collapse supernova is radiated as neutrinos by the cooling neutron star. I will argue that these neutrinos interact with nuclei in the ejected shells of the supernovae to produce new elements. It appears that this nucleosynthesis mechanism is responsible for the galactic abundances of 7 Li, 11 B, 19 F, 138 La, and 180 Ta, and contributes significantly to the abundances of about 15 other light nuclei. I discuss shell model predictions for the charged and neutral current allowed and first-forbidden responses of the parent nuclei, as well as the spallation processes that produce the new elements. 18 refs., 1 fig., 1 tab

Isotope ratio in stellar atmospheres and nucleosynthesis

International Nuclear Information System (INIS)

Barbuy, B.L.S.

1987-01-01

The determination of isotopic ratios in stellar atmospheres is studied. The isotopic shift of atomic and molecular lines of different species of a certain element is examined. CH and MgH lines are observed in order to obtain the 12 C: 13 C and 24 Mg: 25 Mg: 26 Mg isotpic ratios. The formation of lines in stellar atmospheres is computed and the resulting synthetic spectra are employed to determine the isotopic abundances. The results obtained for the isotopic ratios are compared to predictions of nucleosynthesis theories. Finally, the concept of primary and secondary element is discussed, and these definitions are applied to the observed variations in the abundance of elements as a function of metallicity. (author) [pt

np→dγ for big-bang nucleosynthesis

International Nuclear Information System (INIS)

Chen, Jiunn-Wei; Savage, Martin J.

1999-01-01

The cross section for np→dγ is calculated at energies relevant to big-bang nucleosynthesis using the recently developed effective field theory that describes the two-nucleon sector. The E1 amplitude is computed up to N 3 LO and depends only upon nucleon-nucleon phase shift data. In contrast, the M1 contribution is computed up to next-to-leading order, and the four-nucleon-one-magnetic-photon counterterm that enters is determined by the cross section for cold neutron capture. The uncertainty in the calculation for nucleon energies up to E∼1 MeV is estimated to be (less-or-similar sign)4%. (c) 1999 The American Physical Society

Possible evidence for dark radiation from Big Bang Nucleosynthesis data

International Nuclear Information System (INIS)

Flambaum, V.V.; Shuryak, E.V.

2006-01-01

We address the emerging discrepancy between the Big Bang Nucleosynthesis data and standard cosmology, which asks for a bit longer evolution time. If this effect is real, one possible implication (in a framework of brane cosmology model) is that there is a 'dark radiation' component which is negative and makes few percents of ordinary matter density. If so, all scales of this model can be fixed, provided brane-to-bulk leakage problem is solved. (authors)

Early Childhood Development and E-Learning in Africa: The Early Childhood Development Virtual University Programme

Science.gov (United States)

Pence, Alan

2007-01-01

This article explores the development and evaluation of the graduate-level Early Childhood Development Virtual University (ECDVU) programme in Sub-Saharan Africa from 2001 through to 2004. It outlines the history of the ECDVU and the establishing of a Sub-Saharan programme for future leaders in the early childhood field guided by the key principle…

QCD development in the early universe

Energy Technology Data Exchange (ETDEWEB)

Gromov, N. A., E-mail: gromov@dm.komisc.ru [Komi Science Center of the Ural Division of the Russian Academy of Sciences, Department of Mathematics (Russian Federation)

2017-03-15

The high-energy limit of Quantum Chromodynamics is generated by the contraction of its gauge groups. Contraction parameters are taken identical with those of the Electroweak Model and tend to zero when energy increases. At the infinite energy limit all quarks lose masses and have only one color degree of freedom. The limit model represents the development of Quantum Chromodynamics in the early Universe from the Big Bang up to the end of several milliseconds.

Cosmology and the early universe

Science.gov (United States)

Joshi, Abhigna

2017-01-01

In the beginning the universe was in a hot dense state nearly 13.8 billion years ago. The thermal history of the universe was traced back to an era when the temperature was about 1012K. At this early time, the universe was filled with particles-mostly photons and leptons- whose interactions are hopefully weak enough to allow this medium to be treated as a more or less ideal gas. However, if we look back a little further, into the first 0.0001 second of cosmic history when the temperature was above 1012K. At such temperatures, there will be present in thermal equilibrium copious numbers of strongly interacting particles-mostly masons and baryons-with a mean interparticle distance less than a Compton wavelength. These particles will be in a state of continual mutual interaction, and cannot reasonably be expected to obey any simple equation of state. The inflationary epoch lasted from 10-36seconds after the Big Bang to sometime between 10-33and 10-32seconds. Matter and energy created in this time. Right after that space expanded exponentially with enormous rate of 74.3 +/-2.1Km per second per Mpc. Undergraduate student and researcher of the string theory, quantum gravity, cosmology and quantum biology.

Effects of neutrino oscillations on nucleosynthesis and neutrino signals for an 18 M⊙ supernova model

Science.gov (United States)

Wu, Meng-Ru; Qian, Yong-Zhong; Martínez-Pinedo, Gabriel; Fischer, Tobias; Huther, Lutz

2015-03-01

In this paper, we explore the effects of neutrino flavor oscillations on supernova nucleosynthesis and on the neutrino signals. Our study is based on detailed information about the neutrino spectra and their time evolution from a spherically symmetric supernova model for an 18 M⊙ progenitor. We find that collective neutrino oscillations are not only sensitive to the detailed neutrino energy and angular distributions at emission, but also to the time evolution of both the neutrino spectra and the electron density profile. We apply the results of neutrino oscillations to study the impact on supernova nucleosynthesis and on the neutrino signals from a Galactic supernova. We show that in our supernova model, collective neutrino oscillations enhance the production of rare isotopes 138La and 180Ta but have little impact on the ν p -process nucleosynthesis. In addition, the adiabatic Mikheyev-Smirnov-Wolfenstein flavor transformation, which occurs in the C /O and He shells of the supernova, may affect the production of light nuclei such as 7Li and 11B. For the neutrino signals, we calculate the rate of neutrino events in the Super-Kamiokande detector and in a hypothetical liquid argon detector. Our results suggest the possibility of using the time profiles of the events in both detectors, along with the spectral information of the detected neutrinos, to infer the neutrino mass hierarchy.

The thermal evolution of universe: standard model

International Nuclear Information System (INIS)

Nascimento, L.C.S. do.

1975-08-01

A description of the dynamical evolution of the Universe following a model based on the theory of General Relativity is made. The model admits the Cosmological principle,the principle of Equivalence and the Robertson-Walker metric (of which an original derivation is presented). In this model, the universe is considered as a perfect fluid, ideal and symmetric relatively to the number of particles and antiparticles. The thermodynamic relations deriving from these hypothesis are derived, and from them the several eras of the thermal evolution of the universe are established. Finally, the problems arising from certain specific predictions of the model are studied, and the predictions of the abundances of the elements according to nucleosynthesis and the actual behavior of the universe are analysed in detail. (author) [pt

The r-process nucleosynthesis and related challenges

Directory of Open Access Journals (Sweden)

Goriely Stephane

2017-01-01

Full Text Available The rapid neutron-capture process, or r-process, is known to be of fundamental importance for explaining the origin of approximately half of the A > 60 stable nuclei observed in nature. Recently, special attention has been paid to neutron star (NS mergers following the confirmation by hydrodynamic simulations that a non-negligible amount of matter can be ejected and by nucleosynthesis calculations combined with the predicted astrophysical event rate that such a site can account for the majority of r-material in our Galaxy. We show here that the combined contribution of both the dynamical (prompt ejecta expelled during binary NS or NS-black hole (BH mergers and the neutrino and viscously driven outflows generated during the post-merger remnant evolution of relic BH-torus systems can lead to the production of r-process elements from mass number A ≳ 90 up to actinides. The corresponding abundance distribution is found to reproduce the solar distribution extremely well. It can also account for the elemental distributions observed in low-metallicity stars. However, major uncertainties still affect our understanding of the composition of the ejected matter. These concern (i the β-interactions of electron (antineutrinos with free neutrons and protons, as well as their inverse reactions, which may affect the neutron-richness of the matter at the early phase of the ejection, and (ii the nuclear physics of exotic neutron-rich nuclei, including nuclear structure as well as nuclear interaction properties, which impact the calculated abundance distribution. Both aspects are discussed in the light of recent hydrodynamical simulations of NS mergers and microscopic calculations of nuclear decay and reaction probabilities.

Possible evidence for dark radiation from Big Bang Nucleosynthesis data

Energy Technology Data Exchange (ETDEWEB)

Flambaum, V.V. [New South Wales Univ., School of Physics, Sydney NSW (Australia); Argonne National Laboratory, Physics Div., Argonne, IL (United States); Shuryak, E.V. [State University of New York Stony Brook, Dept. of Physics and Astronomy, NY (United States)

2006-06-15

We address the emerging discrepancy between the Big Bang Nucleosynthesis data and standard cosmology, which asks for a bit longer evolution time. If this effect is real, one possible implication (in a framework of brane cosmology model) is that there is a 'dark radiation' component which is negative and makes few percents of ordinary matter density. If so, all scales of this model can be fixed, provided brane-to-bulk leakage problem is solved. (authors)

Lithium in Very Metal-poor Dwarf Stars -- Problems for Standard Big Bang Nucleosynthesis?

International Nuclear Information System (INIS)

Lambert, David L.

2004-01-01

The standard model of primordial nucleosynthesis by the Big Bang as selected by the WMAP-based estimate of the baryon density (Ωbh2) predicts an abundance of 7Li that is a factor of three greater than the generally reported abundance for stars on the Spite plateau, and an abundance of 6Li that is about a thousand times less than is found for some stars on the plateau. This review discusses and examines these two discrepancies. They can likely be resolved without major surgery on the standard model of the Big Bang. In particular, stars on the Spite plateau may have depleted their surface lithium abundance over their long lifetime from the WMAP-based predicted abundances down to presently observed abundances, and synthesis of 6Li (and 7Li) via α + α fusion reactions may have occurred in the early Galaxy. Yet, there remain fascinating ways in which to remove the two discrepancies involving aspects of a new cosmology, particularly through the introduction of exotic particles

Australian Early Childhood Educators: From Government Policy to University Practice

Science.gov (United States)

Davies, Sharon; Trinidad, Sue

2013-01-01

This article provides an overview of the Australian Federal Government initiatives in the area of early childhood with regard to the provision of early childhood education and care. These changes have influenced a Western Australian university to develop an innovative birth to 8 years preservice educator education curriculum. Using an ecological…

Coupled variations of fundamental couplings and primordial nucleosynthesis

International Nuclear Information System (INIS)

Coc, Alain; Nunes, Nelson J.; Olive, Keith A.; Uzan, Jean-Philippe; Vangioni, Elisabeth

2006-10-01

The effect of variations of the fundamental nuclear parameters on big-bang nucleosynthesis are modeled and discussed in detail taking into account the interrelations between the fundamental parameters arising in unified theories. Considering only 4 He, strong constraints on the variation of the neutron lifetime, neutron-proton mass difference are set. These constraints are then translated into constraints on the time variation of the Yukawa couplings and the fine structure constant. Furthermore, we show that a variation of the deuterium binding energy is able to reconcile the 7 Li abundance deduced from the WMAP analysis with its spectroscopically determined value while maintaining concordance with D and 4 He. (authors)

BIG BANG NUCLEOSYNTHESIS WITH A NON-MAXWELLIAN DISTRIBUTION

International Nuclear Information System (INIS)

Bertulani, C. A.; Fuqua, J.; Hussein, M. S.

2013-01-01

The abundances of light elements based on the big bang nucleosynthesis model are calculated using the Tsallis non-extensive statistics. The impact of the variation of the non-extensive parameter q from the unity value is compared to observations and to the abundance yields from the standard big bang model. We find large differences between the reaction rates and the abundance of light elements calculated with the extensive and the non-extensive statistics. We found that the observations are consistent with a non-extensive parameter q = 1 - 0.12 +0.05 , indicating that a large deviation from the Boltzmann-Gibbs statistics (q = 1) is highly unlikely.

Big-bang nucleosynthesis and the relic abundance of dark matter in a stau-neutralino coannihilation scenario

International Nuclear Information System (INIS)

Jittoh, Toshifumi; Koike, Masafumi; Sato, Joe; Yamanaka, Masato; Kohri, Kazunori; Shimomura, Takashi

2008-01-01

A scenario of the big-bang nucleosynthesis is analyzed within the minimal supersymmetric standard model, which is consistent with a stau-neutralino coannihilation scenario to explain the relic abundance of dark matter. We find that we can account for the possible discrepancy of the abundance of 7 Li between the observation and the prediction of the big-bang nucleosynthesis by taking the mass of the neutralino as 300 GeV and the mass difference between the stau and the neutralino as (100-120) MeV. We can therefore simultaneously explain the abundance of the dark matter and that of 7 Li by these values of parameters. The lifetime of staus in this scenario is predicted to be O(100-1000) sec.

Early Universe synthesis of asymmetric dark matter nuggets

Science.gov (United States)

Gresham, Moira I.; Lou, Hou Keong; Zurek, Kathryn M.

2018-02-01

We compute the mass function of bound states of asymmetric dark matter—nuggets—synthesized in the early Universe. We apply our results for the nugget density and binding energy computed from a nuclear model to obtain analytic estimates of the typical nugget size exiting synthesis. We numerically solve the Boltzmann equation for synthesis including two-to-two fusion reactions, estimating the impact of bottlenecks on the mass function exiting synthesis. These results provide the basis for studying the late Universe cosmology of nuggets in a future companion paper.

Early predictors of first-year academic success at university : Pre-university effort, pre-university self-efficacy, and pre-university reasons for attending university

NARCIS (Netherlands)

van Herpen, Sanne G.A.; Meeuwisse, Marieke; Hofman, W. H.Adriaan; Severiens, Sabine E.; Arends, Lidia R.

Given the large number of dropouts in the 1st year at university, it is important to identify early predictors of 1st-year academic success. The present study (n = 453 first-year students) contributes to literature on the transition from secondary to higher education by investigating how the

Concordance of X-ray cluster data with big bang nucleosynthesis in mixed dark matter models

International Nuclear Information System (INIS)

Strickland, R.W.; Schramm, D.N.

1997-01-01

If the hot, X-ray-emitting gas in rich clusters forms a fair sample of the universe as in cold dark matter (CDM) models and the universe is at the critical density Ω T =1, then the data appear to imply a baryon fraction Ω b,X (Ω b,X ≡Ω b derived from X-ray cluster data), larger than that predicted by big bang nucleosynthesis (BBN). While other systematic effects such as clumping can lower Ω b,X , in this paper we use an elementary analysis to show that a simple admixture of hot dark matter (HDM; low-mass neutrinos) with CDM to yield mixed dark matter shifts Ω b,X down so that significant overlap with Ω b from BBN can occur for H 0 approx-lt 73kms -1 Mpc -1 , even without invoking the possible aforementioned effects. The overlap interval is slightly larger for lower mass neutrinos since fewer of them cluster on the scale of the hot X-ray gas. We illustrate this result quantitatively in terms of a simple isothermal model. More realistic velocity dispersion profiles, with less centrally peaked density profiles, imply that fewer neutrinos are trapped and thus further increase the interval of overlap. copyright 1997 The American Astronomical Society

44Ti Nucleosynthesis Lines and Hard X-ray Continuum in Young SNRs: from INTEGRAL to Simbol-X

Science.gov (United States)

Renaud, M.; Terrier, R.; Trap, G.; Lebrun, F.; Decourchelle, A.; Vink, J.

2009-05-01

Supemovae and their remnants are the main Galactic nucleosynthesis sites and the privileged sources of Galactic cosmic rays. The youngest of such remnants can be studied through two distinct observational features: 44Ti γ-ray lines and the hard X-ray nonthermal continuum emission. The former gives unique information on the nucleosynthesis conditions occuring during the first stages of the explosion, while the latter provides clues on acceleration processes at supernova remnant shocks. In this contribution, we present new INTEGRAL results on Tycho, the remnant of a historical supernova, and on G1.9+0.3, which has been recently unveiled as the youngest Galactic supernova remnant. Expectations with Simbol-X are also addressed.

44Ti Nucleosynthesis Lines and Hard X-ray Continuum in Young SNRs: from INTEGRAL to Simbol-X

International Nuclear Information System (INIS)

Renaud, M.; Terrier, R.; Lebrun, F.; Trap, G.; Decourchelle, A.; Vink, J.

2009-01-01

Supemovae and their remnants are the main Galactic nucleosynthesis sites and the privileged sources of Galactic cosmic rays. The youngest of such remnants can be studied through two distinct observational features: 44 Tiγ-ray lines and the hard X-ray nonthermal continuum emission. The former gives unique information on the nucleosynthesis conditions occuring during the first stages of the explosion, while the latter provides clues on acceleration processes at supernova remnant shocks. In this contribution, we present new INTEGRAL results on Tycho, the remnant of a historical supernova, and on G1.9+0.3, which has been recently unveiled as the youngest Galactic supernova remnant. Expectations with Simbol-X are also addressed.

Persistent Tensions in Big Bang Nucleosynthesis and Windows on New Physics

International Nuclear Information System (INIS)

Tytler, David

2009-01-01

Now that we know the baryon to photon ratio to 5% from the cosmic microwave background, Big Bang Nucleosynthesis using standard physics predicts the abundances of five light nuclei with no free parameters. The Deuterium to Hydrogen ratio measured towards quasars agrees with the prediction to within 10%, but there has been tension verging on disagreement between the estimates of the primordial abundances of 4 He and especially 7 Li since 1996. While some recent 4 He measurements agree, the large majority of measurements over the last 30 years have been smaller than the predictions. For 7 Li, the measurements are sufficiently accurate to show that the 7 Li/H in old stars in the halo of our Galaxy is a factor of 3-4 below the predicted ratio. Perhaps stars with a variety of masses have destroyed the same amount of 7 Li, or we already have evidence for new physics. Improved measurements of the primordial abundances could lead to a detection of a wide variety of new physics because BBN is sensitive to all four forces. Examples include new particles that were relativistic during BBN, decaying particles that change the abundances after BBN or a large net lepton number for the universe that changed the neutron to proton ratio and hence the abundances.

Fate of Yang-Mills black hole in early Universe

Energy Technology Data Exchange (ETDEWEB)

Nakonieczny, Lukasz; Rogatko, Marek [Institute of Physics Maria Curie-Sklodowska University 20-031 Lublin, pl. Marii Curie-Sklodowskiej 1 (Poland)

2013-02-21

According to the Big Bang Theory as we go back in time the Universe becomes progressively hotter and denser. This leads us to believe that the early Universe was filled with hot plasma of elementary particles. Among many questions concerning this phase of history of the Universe there are questions of existence and fate of magnetic monopoles and primordial black holes. Static solution of Einstein-Yang-Mills system may be used as a toy model for such a black hole. Using methods of field theory we will show that its existence and regularity depend crucially on the presence of fermions around it.

Developments in inflationary cosmology

Indian Academy of Sciences (India)

dominate the energy density of the universe for some short time period in the early phases of ..... decay rate would be long enough to affect nucleosynthesis. ..... neous solution contains the past memory of the mode and once it stops decaying.

Particle physics and cosmology. Progress report, September 1, 1982-August 31, 1983

International Nuclear Information System (INIS)

Schramm, D.N.; Turner, M.S.

1983-05-01

Brief summaries are presented of research done in the following areas: constraints on particle properties; Big Bang nucleosynthesis; baryogenesis; phase transitions in the early universe; galaxy formation; magnetic monopoles; exotic dark matter; cosmological inflation; and ultra-high energy cosmic rays

Universality and the astrophysical sites for the r-process

International Nuclear Information System (INIS)

Otsuki, Kaori; Mathews, Grant J.; Wilson, James; Kajino, Toshitaka; Aoki, Wako; Honda, Satoshi

2003-01-01

Several observations of r-process elements in metal-deficient halo stars have been reported which show a Z>56 formed abundance distribution pattern similar to the Solar-system r-process distribution. It was believed that r-process elements for Z>56 in the same ratio and their astrophysical origin is unique because of this. However, quite recently, several controversial observational results have been reported. We calculated nucleosynthesis in various environments using a dynamical code. We find it is possible to reproduce the observed universal abundance distribution for stable Z>56 elements in various environments. Our results do not support a unique astrophysical site for Z>56 elements. These results significantly affect nuclear chronology using actinide elements. We also introduce a recent r-process nucleosynthesis calculation based on a supernovae simulation. Our tentative results indicate over-production of lighter elements and a shortage of actinide elements. (author)

On the introduction of {sup 17}O+p reaction rates evaluated through the THM in AGB nucleosynthesis calculations

Energy Technology Data Exchange (ETDEWEB)

Palmerini, S.; Sergi, M. L.; La Cognata, M.; Pizzone, R. G. [I.N.F.N. Laboratori Nazionali del Sud, via Santa Sofia 62, Catania (Italy); Lamia, L.; Spitaleri, C. [Dipartimento di Fisica e Astronomia, Universitá degli Studi di Catania (Italy)

2014-05-09

The rates for the {sup 17}O(p,αα{sup 14}N, {sup 17}O(p,α){sup 18}F and {sup 18}O(p,α){sup 15}N reactions deduced trough the Trojan Horse Method (THM) have been introduced into a state-of-the-art asymptotic giant branch (AGB) models for proton-capture nucleosynthesis and cool bottom process. The predicted abundances have been compared with isotopic compositions provided by geochemical analysis of presolar grains. As a result, an improved agreement is found between the models and the isotopic mix of oxide grains of AGB origins, whose composition is the signature of low-temperature proton-capture nucleosynthesis.

Collective neutrino oscillations and r-process nucleosynthesis in supernovae

Science.gov (United States)

Duan, Huaiyu

2012-10-01

Neutrinos can oscillate collectively in a core-collapse supernova. This phenomenon can occur much deeper inside the supernova envelope than what is predicted from the conventional matter-induced Mikheyev-Smirnov-Wolfenstein effect, and hence may have an impact on nucleosynthesis. The oscillation patterns and the r-process yields are sensitive to the details of the emitted neutrino fluxes, the sign of the neutrino mass hierarchy, the modeling of neutrino oscillations and the astrophysical conditions. The effects of collective neutrino oscillations on the r-process will be illustrated using representative late-time neutrino spectra and outflow models.

Revisiting big-bang nucleosynthesis constraints on dark-matter annihilation

Energy Technology Data Exchange (ETDEWEB)

Kawasaki, Masahiro [Institute for Cosmic Ray Research, The University of Tokyo, Kashiwa 277-8582 (Japan); Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa 277-8583 (Japan); Kohri, Kazunori [Theory Center, IPNS, KEK, Tsukuba 305-0801 (Japan); Sokendai, Tsukuba 305-0801 (Japan); Moroi, Takeo [Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa 277-8583 (Japan); Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan); Takaesu, Yoshitaro, E-mail: takaesu@hep-th.phys.s.u-tokyo.ac.jp [Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan)

2015-12-17

We study the effects of dark-matter annihilation during the epoch of big-bang nucleosynthesis on the primordial abundances of light elements. We improve the calculation of the light-element abundances by taking into account the effects of anti-nucleons emitted by the annihilation of dark matter and the interconversion reactions of neutron and proton at inelastic scatterings of energetic nucleons. Comparing the theoretical prediction of the primordial light-element abundances with the latest observational constraints, we derive upper bounds on the dark-matter pair-annihilation cross section. Implication to some of particle-physics models are also discussed.

Revisiting big-bang nucleosynthesis constraints on dark-matter annihilation

Directory of Open Access Journals (Sweden)

Masahiro Kawasaki

2015-12-01

Full Text Available We study the effects of dark-matter annihilation during the epoch of big-bang nucleosynthesis on the primordial abundances of light elements. We improve the calculation of the light-element abundances by taking into account the effects of anti-nucleons emitted by the annihilation of dark matter and the interconversion reactions of neutron and proton at inelastic scatterings of energetic nucleons. Comparing the theoretical prediction of the primordial light-element abundances with the latest observational constraints, we derive upper bounds on the dark-matter pair-annihilation cross section. Implication to some of particle-physics models are also discussed.

Measurement of Reactions on 30P for Nova Nucleosynthesis

Science.gov (United States)

Ma, Z.; Guidry, M. W.; Hix, W. R.; Smith, M. S.

2003-05-01

Replace these paragraphs with your abstract. We encourage you to include a sentence acknowledging your funding agency. In a recent study the 30P(p,gamma)31S rate played a crucial role in the synthesis of heavier nuclear species, from Si to Ca, in nova outbursts on ONe White Dwarfs [1]. The adopted rate of this reaction, based on a Hauser-Feshbach calculation [2], has a large uncertainty and could be as much as a factor of 100 too high or too low [3]. In their study, Jose et al.[1] varied the 30P(p,gamma)31S reaction rate within this uncertainty and found that, when rate is reduced by a factor of 100, the synthesis of elements above Si is lowered by a factor 10 with respect to the values found with the nominal rate. This has important consequences for nova nucleosynthesis, as overproduction of isotopes in the Si to Ca mass region has been observed in the ejecta from some nova explosions (e.g.,[4,5]). While generally valid at higher temperatures, Hauser-Feshbach calculations of the rates at nova temperatures can have large uncertainties. At these temperatures, the rate is more likely dominated by a few individual nuclear resonances. At present there are about 10 31S resonances known above the 30P + p threshold that may contribute to the 30P(p,gamma)31S reaction rate at nova temperatures. The excitation energies of these levels are known but spins and parities (for all but two) are not. We plan to measure the 30P(p,p)30P and 30P(p,gamma)31S reactions at HRIBF to better determine this reaction rate. A detailed description of the experiments will be given. We are also conducting a new nova nucleosynthesis simulation over multiple spatial zones of the exploding envelope to investigate the influence of the 30P(p,gamma)31S reaction rate on nova nucleosynthesis. The results of these calculations will be discussed. 1. Jose , J., Coc, A., Hernanz, M., Astrophys. J., 560, 897(2001). 2. Thielemann, F.-K et al., 1987, Advances in Nuclear Astrophysics, ed. E. Vangioni-Flam ( Gif

Neutrino nucleosynthesis in core-collapse Supernova explosions

Directory of Open Access Journals (Sweden)

Sieverding A.

2016-01-01

Full Text Available The neutrino-induced nucleosynthesis (ν process in supernova explosions of massive stars of solar metallicity with initial main sequence masses between 15 and 40 M⊙ has been studied. A new extensive set of neutrino-nucleus cross-sections for all the nuclei included in the reaction network is used and the average neutrino energies are reduced to agree with modern supernova simulations. Despite these changes the ν process is found to contribute still significantly to the production of the nuclei 7Li, 11B, 19F, 138La and 180Ta, even though the total yields for those nuclei are reduced. Furthermore we study in detail contributions of the ν process to the production of radioactive isotopes 26Al, 22Na and confirm the production of 92Nb and 98Tc.

Neutrino nucleosynthesis in core-collapse Supernova explosions

Science.gov (United States)

Sieverding, A.; Huther, L.; Martínez-Pinedo, G.; Langanke, K.; Heger, A.

2018-01-01

The neutrino-induced nucleosynthesis (v process) in supernova explosions of massive stars of solar metallicity with initial main sequence masses between 15 and 40 M⨀ has been studied. A new extensive set of neutrino-nucleus cross-sections for all the nuclei included in the reaction network is used and the average neutrino energies are reduced to agree with modern supernova simulations. Despite these changes the v process is found to contribute still significantly to the production of the nuclei 7Li, 11B, 19F, 138La and 180Ta, even though the total yields for those nuclei are reduced. Furthermore we study in detail contributions of the v process to the production of radioactive isotopes 26Al, 22Na and confirm the production of 92Nb and 98Tc.

Big Bang Nucleosynthesis: Impact of Nuclear Physics Uncertainties on Baryonic Matter Density

International Nuclear Information System (INIS)

Smith, Michael Scott; Roberts, Luke F.; Hix, William Raphael; Bruner, Blake D.; Kozub, R.L.; Tytler, David; Fuller, George M.; Lingerfelt, Eric J.; Nesaraja, Caroline D

2008-01-01

We performed new Big Bang Nucleosynthesis simulations with the bigbangonline.org suite of codes to determine, from the nuclear physics perspective, the highest achievable precision of the constraint on the baryon-to-photo ratio η given current observational uncertainties. We also performed sensitivity studies to determine the impact that particular nuclear physics measurements would have on the uncertainties of predicted abundances and on the η constraint.

Galactic Pairs in the Early Universe

Science.gov (United States)

Kohler, Susanna

2018-02-01

In the spirit of Valentines Day, today well be exploring apparent pairs of galaxies in the distant, early universe. How can we tell whether these duos are actually paired galaxies, as opposed to disguised singles?Real Pair, or Trick of the Light?In the schematic timeline of the universe, the epoch of reionization is when the first galaxies and quasars began to form and evolve. [NASA]The statistics of merging galaxies throughout the universe reveal not only direct information about how galaxies interact, but also cosmological information about the structure of the universe. While weve observed many merging galaxy pairs at low redshift, however, its much more challenging to identify these duos in the early universe.A merging pair of galaxies at high redshift appears to us as a pair of unresolved blobs that lie close to each other in the sky. But spotting such a set of objects doesnt necessarily mean were looking at a merger! There are three possible scenarios to explain an observed apparent duo:Its a pair of galaxies in a stage of merger.Its a projection coincidence; the two galaxies arent truly near each other.Its a single galaxy being gravitationally lensed by a foreground object. This strong lensing produces the appearance of multiple galaxies.Hubble photometry of one of the three galaxy groups identified at z 8, with the galaxies in the image labeled with their corresponding approximate photometric redshifts. [Adapted from Chaikin et al. 2018]Hunting for Distant DuosIn a recent study led by Evgenii Chaikin (Peter the Great St. Petersburg Polytechnic University, Russia), a team of scientists has explored the Hubble Ultra Deep Field in search ofhigh-redshift galaxies merging during the epoch of reionization, when the first galaxies formed and evolved.Using an approach called the dropout technique, which leverages the visibility of the galaxies in different wavelength filters, Chaikin and collaborators obtain approximate redshifts for an initial sample of 7

On a chaotic early universe

International Nuclear Information System (INIS)

Tomita, Kenji.

1974-11-01

The theories regarding the origin of galaxies and elements are reviewed in this paper, and the assumptions made for these theories are discussed. It has been assumed that the universe has always been isotropic and homogeneous from the beginning of cosmic expansion. At the stage of very high density that any local irregularities such as galaxies cannot exist, the admissible deviation in this case from the mean value is only the statistical or quantum fluctuation of matter density, spatial curvature or their growth. It should be considered that the chemical composition of matters at the earliest stage consisted of most fundamental particles. However, if the fluctuation of matter density is statistical, the present values are too small. As for the origin of elements, it depends strongly on the period when cosmic radiation appeared. The final mass ratios of elements are given from the present baryon mass density, and are in agreement with observed values. The assumption of hot universe seems good. However, the time-independent ratio of photon number to baryon number is hardly understood. It is reasonable to assume for the early universe an inhomogeneous model whose space-time curvature is of turbulent character, according to weak cosmological principle. The inhomogeneous models to be considered are weakly non-linear perturbation theory, anti-Newtonian approximation and post anti-Newtonian approximation. Smoothing-out process, the origin of cosmic microwave radiation, the origin of galaxies and the origin of chemical elements are discussed. (Kato, T.)

Extended thermodynamics in the early Universe

International Nuclear Information System (INIS)

Lukacs, B.

1985-01-01

It is a general belief that in some early stages of the evolution of the Universe, unequilibrium situations played important role. In order to incorporate some deviations from thermal equilibrium into the description of the evolution, an extension of the thermodynamic formalism is given, where, using the notion of ekaentropy, new terms are introduced into the Gibbs-Duhem relation for representing the deviation. Two situations are investigated in simplified models: the primordial thermalization in the symmetric phase of GUT, and the development of a nonthermal distribution for massive neutrinos. (author)

Astrophysical neutron capture rates in s- and r-process nucleosynthesis

International Nuclear Information System (INIS)

Beer, H.; Mohr, P.; Oberhummer, H.; Rauscher, T.; Mutti, P.; Corvi, F.; Sedyshev, P.V.; Popov, Yu.P.

1997-01-01

The astrophysical neutron capture rates of light and heavy nuclei are measured and calculated. The measurements are realized using the activation technique at the 3.75 MV Karlsruhe Van de Graaff accelerator and by means of the time-of-flight method at the Geel electron linear accelerator (GELINA). The setup for the fast cyclic activation measurements made on 26 Mg and 48 Ca, as well as on Pt isotopes is described. The time-of-flight method is used for neutron capture measurements of the bottleneck isotopes 138 Ba and 208 Pb. The calculations are made using direct and compound nuclear capture models. The s-process nucleosynthesis path in the Os and Pt mass region is discussed in details. It is shown that for 19 '1 Os, 192 Ir and 193 Pt there is a competition between β-decay and neutron capture. The β-decay half-lives are dependent on temperature and electron density of the s-process environment. The abundance of s-only 192 Pt originates from the branching at 191 Os and 192 Ir. The isotopes 190 Pt and 198 Pt are not on the s-process path, therefore the seed abundance vanish during nucleosynthesis. Calculations are carried out using parametrized models in order to reproduce the s-process abundance in the mass region from Os up to Pt. The neutron density is adjusted to reproduce the solar abundance of the s-only isotope 9 2 Pt in the analysis of the present branching especially

CP-Violating solitons in the early universe

International Nuclear Information System (INIS)

Tornkvist, O.; Riotto, A.

1997-07-01

Solitons in extensions of the Standard Model can serve as localized sources of CP violation. Depending on their stability properties, they may serve either to create or to deplete the baryon asymmetry. The conditions for existence of a particular soliton candidate, the membrane solution of the two-Higgs model, are presented. In the generic case, investigated by Bachas and Tomaras, membranes exist and are metastable for a wide range of parameters. For the more viable supersymmetric case, it is shown that the present-day existence of CP-violating membranes is experimentally excluded, but preliminary studies suggest that they may have existed in the early universe soon after the electroweak phase transition, with important consequences for the baryon asymmetry of the universe

Gauge theories, time-dependence of the gravitational constant and antigravity in the early universe

International Nuclear Information System (INIS)

Linde, A.D.

1980-01-01

It is shown that the interaction of the gravitational field with matter leads to a strong modification of the effective gravitational constant in the early universe. In certain cases this leads even to the change of sign of the gravitational constant, i.e. to antigravity in the early universe. (orig.)

COMPACT STELLAR BINARY ASSEMBLY IN THE FIRST NUCLEAR STAR CLUSTERS AND r-PROCESS SYNTHESIS IN THE EARLY UNIVERSE

International Nuclear Information System (INIS)

Ramirez-Ruiz, Enrico; MacLeod, Morgan; Trenti, Michele; Roberts, Luke F.; Lee, William H.; Saladino-Rosas, Martha I.

2015-01-01

Investigations of elemental abundances in the ancient and most metal deficient stars are extremely important because they serve as tests of variable nucleosynthesis pathways and can provide critical inferences of the type of stars that lived and died before them. The presence of r-process elements in a handful of carbon-enhanced metal-poor (CEMP-r) stars, which are assumed to be closely connected to the chemical yield from the first stars, is hard to reconcile with standard neutron star mergers. Here we show that the production rate of dynamically assembled compact binaries in high-z nuclear star clusters can attain a sufficient high value to be a potential viable source of heavy r-process material in CEMP-r stars. The predicted frequency of such events in the early Galaxy, much lower than the frequency of Type II supernovae but with significantly higher mass ejected per event, can naturally lead to a high level of scatter of Eu as observed in CEMP-r stars

COMPACT STELLAR BINARY ASSEMBLY IN THE FIRST NUCLEAR STAR CLUSTERS AND r-PROCESS SYNTHESIS IN THE EARLY UNIVERSE

Energy Technology Data Exchange (ETDEWEB)

Ramirez-Ruiz, Enrico; MacLeod, Morgan [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Trenti, Michele [Kavli Institute for Cosmology and Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Roberts, Luke F. [TAPIR, California Institute of Technology, Pasadena, California 91125 (United States); Lee, William H.; Saladino-Rosas, Martha I. [Instituto de Astronomía, Universidad Nacional Autónoma de México, México DF 04510, México (Mexico)

2015-04-01

Investigations of elemental abundances in the ancient and most metal deficient stars are extremely important because they serve as tests of variable nucleosynthesis pathways and can provide critical inferences of the type of stars that lived and died before them. The presence of r-process elements in a handful of carbon-enhanced metal-poor (CEMP-r) stars, which are assumed to be closely connected to the chemical yield from the first stars, is hard to reconcile with standard neutron star mergers. Here we show that the production rate of dynamically assembled compact binaries in high-z nuclear star clusters can attain a sufficient high value to be a potential viable source of heavy r-process material in CEMP-r stars. The predicted frequency of such events in the early Galaxy, much lower than the frequency of Type II supernovae but with significantly higher mass ejected per event, can naturally lead to a high level of scatter of Eu as observed in CEMP-r stars.

Cosmological Imprints of a Generalized Chaplygin Gas Model for the Early Universe

Energy Technology Data Exchange (ETDEWEB)

Bouhmadi-Lopez, Mariam; /Lisbon, CENTRA; Chen, Pisin; /Taiwan, Natl. Taiwan U. /KIPAC, Menlo Park /SLAC; Liu, Yen-Wei; /Taiwan, Natl. Taiwan U.

2012-06-06

We propose a phenomenological model for the early universe where there is a smooth transition between an early quintessence phase and a radiation-dominated era. The matter content is modeled by an appropriately modified Chaplygin gas for the early universe. We constrain the model observationally by mapping the primordial power spectrum of the scalar perturbations to the latest data of WMAP7. We compute as well the spectrum of the primordial gravitational waves as would be measured today. We show that the high frequencies region of the spectrum depends on the free parameter of the model and most importantly this region of the spectrum can be within the reach of future gravitational waves detectors.

Lorentz invariance violation in the neutrino sector: a joint analysis from big bang nucleosynthesis and the cosmic microwave background

Energy Technology Data Exchange (ETDEWEB)

Dai, Wei-Ming; Cai, Rong-Gen [Chinese Academy of Sciences, CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, P.O. Box 2735, Beijing (China); University of Chinese Academy of Sciences, School of Physical Sciences, Beijing (China); Guo, Zong-Kuan [Chinese Academy of Sciences, CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, P.O. Box 2735, Beijing (China); University of Chinese Academy of Sciences, School of Astronomy and Space Science, Beijing (China); Zhang, Yuan-Zhong [Chinese Academy of Sciences, CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, P.O. Box 2735, Beijing (China)

2017-06-15

We investigate constraints on Lorentz invariance violation in the neutrino sector from a joint analysis of big bang nucleosynthesis and the cosmic microwave background. The effect of Lorentz invariance violation during the epoch of big bang nucleosynthesis changes the predicted helium-4 abundance, which influences the power spectrum of the cosmic microwave background at the recombination epoch. In combination with the latest measurement of the primordial helium-4 abundance, the Planck 2015 data of the cosmic microwave background anisotropies give a strong constraint on the deformation parameter since adding the primordial helium measurement breaks the degeneracy between the deformation parameter and the physical dark matter density. (orig.)

Lorentz invariance violation in the neutrino sector: a joint analysis from big bang nucleosynthesis and the cosmic microwave background

International Nuclear Information System (INIS)

Dai, Wei-Ming; Cai, Rong-Gen; Guo, Zong-Kuan; Zhang, Yuan-Zhong

2017-01-01

We investigate constraints on Lorentz invariance violation in the neutrino sector from a joint analysis of big bang nucleosynthesis and the cosmic microwave background. The effect of Lorentz invariance violation during the epoch of big bang nucleosynthesis changes the predicted helium-4 abundance, which influences the power spectrum of the cosmic microwave background at the recombination epoch. In combination with the latest measurement of the primordial helium-4 abundance, the Planck 2015 data of the cosmic microwave background anisotropies give a strong constraint on the deformation parameter since adding the primordial helium measurement breaks the degeneracy between the deformation parameter and the physical dark matter density. (orig.)

Lorentz invariance violation in the neutrino sector: a joint analysis from big bang nucleosynthesis and the cosmic microwave background

Science.gov (United States)

Dai, Wei-Ming; Guo, Zong-Kuan; Cai, Rong-Gen; Zhang, Yuan-Zhong

2017-06-01

We investigate constraints on Lorentz invariance violation in the neutrino sector from a joint analysis of big bang nucleosynthesis and the cosmic microwave background. The effect of Lorentz invariance violation during the epoch of big bang nucleosynthesis changes the predicted helium-4 abundance, which influences the power spectrum of the cosmic microwave background at the recombination epoch. In combination with the latest measurement of the primordial helium-4 abundance, the Planck 2015 data of the cosmic microwave background anisotropies give a strong constraint on the deformation parameter since adding the primordial helium measurement breaks the degeneracy between the deformation parameter and the physical dark matter density.

Electron Capture Cross Sections for Stellar Nucleosynthesis

Directory of Open Access Journals (Sweden)

P. G. Giannaka

2015-01-01

Full Text Available In the first stage of this work, we perform detailed calculations for the cross sections of the electron capture on nuclei under laboratory conditions. Towards this aim we exploit the advantages of a refined version of the proton-neutron quasiparticle random-phase approximation (pn-QRPA and carry out state-by-state evaluations of the rates of exclusive processes that lead to any of the accessible transitions within the chosen model space. In the second stage of our present study, we translate the abovementioned e--capture cross sections to the stellar environment ones by inserting the temperature dependence through a Maxwell-Boltzmann distribution describing the stellar electron gas. As a concrete nuclear target we use the 66Zn isotope, which belongs to the iron group nuclei and plays prominent role in stellar nucleosynthesis at core collapse supernovae environment.

Nucleosynthesis in neutrino-driven winds: Influence of the nuclear physics input

International Nuclear Information System (INIS)

Arcones, Almudena; Martinez-Pinedo, Gabriel

2010-01-01

We have performed hydrodynamical simulations of the long-time evolution of proto-neutron stars to study the nucleosynthesis using the resulting wind trajectories. Although the conditions found in the present wind models are not favourable for the production of heavy elements, a small enhancement of the entropy results in the production of r-process elements with A ∼ 195. This allows us to explore the sensitivity of their production to the hydrodynamical evolution (wind termination shock) and nuclear physics input used.

Early Presbyterian influences at the University of Pretoria

Directory of Open Access Journals (Sweden)

Graham Duncan

2008-01-01

Full Text Available Presbyterianism, through two significant personalities, provided an important impetus to the formation and development of the early University of Pretoria. Their contribution has to be understood in terms of the contexts of their Scottish Presbyterian heritage, South Africa in the early years of the twentieth century and the state of higher education prevalent at that time. Together these contexts may be described as political, religious and educational. Prof AC Paterson made significant contributions both in teaching and administration at the institutional level. Prof E Macmillan made his contribution in the field of teaching, but never divorced from the very context where ministry has to be exercised.

182Hf: a new stopwatch for the early solar system

International Nuclear Information System (INIS)

Norman, E.B.; Schramm, D.N.

1983-01-01

It is now well established that live 26 Al (t/sub 1/2/ = 7.2 x 10 5 yr) and 107 Pd (t/sub 1/2/ = 6.5 x 10 6 yr) were present in the early solar system. Thus, the nucleosynthetic vent (supernova) responsible for the production of these nuclei must have occurred no more than a few million years prior to the formation of solid bodies. It is possible that this event also produced the 129 I known to be present in the early solar system. However, the last event to contribute 244 Pu to the solar system occurred approx. 10 8 yr prior to the time of solidification. This latter time scale is also consistent with the lack of evidence for a 247 Cm chronometer. In this letter, we propose that 182 Hf (t/sub 1/2/ = 9 x 10 6 yr) can resolve the question of whether heavy-element non-actinide nucleosynthesis occurred during the 26 Al-producing event. The answer to this question will help to clarify the chronology of the formation of the solar system and will help to determine the astrophysical sites of heavy-element nucleosynthesis

Big Bang nucleosynthesis and the quark-hadron transition

International Nuclear Information System (INIS)

Kurki-suonio, H.; Matzner, R.A.; Olive, K.A.; Schramm, D.N.

1989-12-01

An examination and brief review is made of the effects of quark-hadron transistion induced fluctuations on Big Bang nucleosynthesis. It is shown that cosmologically critical densities in baryons are difficult to reconcile with observation, but the traditional baryon density constraints from homogeneous calculations might be loosened by as much as 50 percent, to 0.3 of critical density, and the limit on the number of neutrino flavors remains about N(sub nu) is less than or approximately 4. To achieve baryon densities of greater than or approximately 0.3 of critical density would require initial density contrasts R much greater than 10(exp 3), whereas the simplest models for the transition seem to restrict R to less than approximately 10(exp 2)

Big bang nucleosynthesis and the quark-hadron transition

Science.gov (United States)

Kurki-Suonio, Hannu; Matzner, Richard A.; Olive, Keith A.; Schramm, David N.

1990-01-01

An examination and brief review is made of the effects of quark-hadron transition induced fluctuations on Big Bang nucleosynthesis. It is shown that cosmologically critical densities in baryons are difficult to reconcile with observation, but the traditional baryon density constraints from homogeneous calculations might be loosened by as much as 50 percent, to 0.3 of critical density, and the limit on the number of neutrino flavors remains about N(sub nu) is less than or approximately 4. To achieve baryon densities of greater than or approximately 0.3 of critical density would require initial density contrasts R is much greater the 10(exp e), whereas the simplest models for the transition seem to restrict R to less than of approximately 10(exp 2).

Recent results in explosive and s-process nucleosynthesis from measurements on radioactive and stable targets

International Nuclear Information System (INIS)

Koehler, P.E.; Kaeppeler, F.; Schatz, H.

1993-01-01

Measurements of (n,p) and (n,α) cross sections are crucial for a better understanding of many scenarios of nucleosynthesis. Current problems in which such reactions play a roll include the possible synthesis of heavy element during the big bang. The production of several rare isotopes in explosive nucleosynthesis, and a better understanding of the role of the s process in the synthesis of light and intermediate mass nuclei. We have recently completed measurements of several (n,p) and (n,α) cross sections of importance to nuclear astrophysics. The cross sections were measured in the range from thermal energy to approximately 1 MeV by using the white neutron source at the Manuel Lujan, Jr. Neutron Scattering Center (LANSCE) in Los Alamos. We have also made complementary measurements at the Karlsruhe Van de Graaff and at thee Oak Ridge Electron Linear Accelerator (ORELA). We discuss the impact of the results on nuclear astrophysics as well as recent improvements and future plans

Astrophysical Li-7 as a product of big bang nucleosynthesis and galactic cosmic-ray spallation

Science.gov (United States)

Olive, Keith A.; Schramm, David N.

1992-01-01

The astrophysical Li-7 abundance is considered to be largely primordial, while the Be and B abundances are thought to be due to galactic cosmic ray (GCR) spallation reactions on top of a much smaller big bang component. But GCR spallation should also produce Li-7. As a consistency check on the combination of big bang nucleosynthesis and GCR spallation, the Be and B data from a sample of hot population II stars is used to subtract from the measured Li-7 abundance an estimate of the amount generated by GCR spallation for each star in the sample, and then to add to this baseline an estimate of the metallicity-dependent augmentation of Li-7 due to spallation. The singly reduced primordial Li-7 abundance is still consistent with big bang nucleosynthesis, and a single GCR spallation model can fit the Be, B, and corrected Li-7 abundances for all the stars in the sample.

Nucleosynthesis Modes in the High-Entropy-Wind Scenario of Type II Supernovae

International Nuclear Information System (INIS)

Farouqi, K.; Kratz, K.-L.; Cowan, J. J.; Mashonkina, L. I.; Pfeiffer, B.; Sneden, C.; Thielemann, F.-K.; Truran, J. W.

2008-01-01

In an attempt to constrain the astrophysical conditions for the nucleosynthesis of the classical r-process elements beyond Fe, we have performed large-scale dynamical network calculations within the model of an adiabatically expanding high- entropy wind (HEW) of type II supernovae (SN II). A superposition of several entropy-components (S) with model-inherent weightings results in an excellent reproduction of the overall Solar System (SS) isotopic r-process residuals (N r,· ), as well as the more recent observations of elemental abundances of metal-poor, r-process rich halo stars in the early Galaxy. For the heavy r-process elements beyond Sn, our HEW model predicts a robust abundance pattern up to the Th, U r-chronometer region. For the lighter neutron-capture region, an S-dependent superposition of (i) a normal α-component directly producing stable nuclei, including s-only isotopes, and (ii) a component from a neutron-rich α-freezeout followed by the rapid recapture of β-delayed neutrons (βdnrpar; emitted from the far-unstable seed nuclei is indicated. In agreement with several recent halo-star observations in the 60< A<110 region, our HEW model confirms a Z-dependent non-correlation, respectively partial correlation with the heavier ''main'' r-process elements

The Cosmic Microwave Background Radiation-A Unique Window on the Early Universe

Science.gov (United States)

Hinshaw, Gary

2010-01-01

The cosmic microwave background radiation is the remnant heat from the Big Bang. It provides us with a unique probe of conditions in the early universe, long before any organized structures had yet formed. The anisotropy in the radiation's brightness yields important clues about primordial structure and additionally provides a wealth of information about the physics of the early universe. Within the framework of inflationary dark matter models, observations of the anisotropy on sub-degree angular scales reveals the signatures of acoustic oscillations of the photon-baryon fluid at a redshift of 11 00. Data from the first seven years of operation of the Wilkinson Microwave Anisotropy Probe (WMAP) satellite provide detailed full-sky maps of the cosmic microwave background temperature and polarization anisotropy. Together, the data provide a wealth of cosmological information, including the age of the universe, the epoch when the first stars formed, and the overall composition of baryonic matter, dark matter, and dark energy. The results also provide constraints on the period of inflationary expansion in the very first moments of time. WMAP, part of NASA's Explorers program, was launched on June 30, 2001. The WMAP satellite was produced in a partnership between the Goddard Space Flight Center and Princeton University. The WMAP team also includes researchers at the Johns Hopkins University; the Canadian Institute of Theoretical Astrophysics; University of Texas; Oxford University; University of Chicago; Brown University; University of British Columbia; and University of California, Los Angeles.

Was there an early reionization component in our universe?

Science.gov (United States)

Villanueva-Domingo, Pablo; Gariazzo, Stefano; Gnedin, Nickolay Y.; Mena, Olga

2018-04-01

A deep understanding of the epoch of reionization is still missing in our knowledge of the universe. While future probes will allow us to test the precise evolution of the free electron fraction from redshifts between zsimeq 6 and 0zsimeq 2, at present one could ask what kind of reionization processes are allowed by present cosmic microwave background temperature and polarization measurements. An early contribution to reionization could imply a departure from the standard picture where star formation determines the reionization onset. By considering a broad class of possible reionization parameterizations, we find that current data do not require an early reionization component in our universe and that only one marginal class of models, based on a particular realization of reionization, may point to that. In addition, the frequentist Akaike information criterion (AIC) provides strong evidence against alternative reionization histories, favoring the most simple reionization scenario, which describes reionization by means of only one (constant) reionization optical depth τ.

Was there an early reionization component in our universe?

Energy Technology Data Exchange (ETDEWEB)

Villanueva-Domingo, Pablo; Gariazzo, Stefano; Gnedin, Nickolay Y.; Mena, Olga

2018-04-01

A deep understanding of the Epoch of Reionization is still missing in our knowledge of the universe. While future probes will allow us to test the precise evolution of the free electron fraction from redshifts between $z\\simeq 6$ and $z\\simeq 20$, at present one could ask what kind of reionization processes are allowed by present Cosmic Microwave Background temperature and polarization measurements. An early contribution to reionization could imply a departure from the standard picture where star formation determines the reionization onset. BBy considering a broad class of possible reionization parameterizations, we find that current data do not require an early reionization component in our universe and that only one marginal class of models, based on a particular realization of reionization, may point to that. In addition, the frequentist Akaike Information Criterion (AIC) provides strong evidence against alternative reionization histories, favoring the most simple reionization scenario, which describes reionization by means of only one (constant) reionization optical depth $\\tau$.

Fission and r-process nucleosynthesis in neutron star mergers

International Nuclear Information System (INIS)

Giuliani, Samuel Andrea

2018-01-01

Fission plays a crucial role for the r-process nucleosynthesis in neutron star mergers. Due to the high neutron densities achieved in this astrophysical scenario the sequence of neutron captures and beta decays that constitutes the r process produces superheavy neutron rich nuclei that become unstable against fission. Fission determines thus the heaviest nuclei that can be produced by the r process and the fission yields shape the abundances of lighter nuclei. But despite the key role of fission the sensitivity of the r-process nucleosynthesis to uncertainties in fission predictions has not been explored. Nowadays there are only few set of fission rates suited for r-process calculations and most of them rely on a simplified treatment of the fission process. In this thesis we go beyond these approximations and compute the fission properties of r-process nuclei using the energy density functional approach. Fission is described as a tunneling process where the nucleus ''moves'' in a collective space characterized by coordinates describing the nuclear shape. Thus fission depends on the evolution of the energy with the deformation but also on the inertia due to the motion in the collective space. This is analogous to the quantum mechanical tunneling of a particle inside a potential well. In our study the relevant quantities for the description of the fission process are consistently computed for 3642 nuclei following the Hartree-Fock-Bogolyubov theory with constraining operators. We perform an extensive benchmark against the available experimental data and explore the variations of the fission properties along the superheavy landscape. We find that while collective inertias have a strong impact in the fission probabilities of light nuclei their role becomes less relevant in r -process nuclei. Within the statistical model we compute the neutron induced stellar reaction rates relevant for the r-process nucleosynthesis. These sets of stellar reaction

The Early Universe: Searching for Evidence of Cosmic Inflation

Science.gov (United States)

Chuss, David T.

2012-01-01

In the past two decades, our understanding of the evolution and fate of the universe has increased dramatically. This "Age of Precision Cosmology" has been ushered in by measurements that have both elucidated the details of the Big Bang cosmology and set the direction for future lines of inquiry. Our universe appears to consist of 5% baryonic matter; 23% of the universe's energy content is dark matter which is responsible for the observed structure in the universe; and 72% of the energy density is so-called "dark energy" that is currently accelerating the expansion of the universe. In addition, our universe has been measured to be geometrically flat to 1 %. These observations and related details of the Big Bang paradigm have hinted that the universe underwent an epoch of accelerated expansion known as "inflation" early in its history. In this talk, I will review the highlights of modern cosmology, focusing on the contributions made by measurements of the cosmic microwave background, the faint afterglow of the Big Bang. I will also describe new instruments designed to measure the polarization of the cosmic microwave background in order to search for evidence of cosmic inflation.

Big Bang Nucleosynthesis: Impact of Nuclear Physics Uncertainties on Baryonic Matter Density Constraints

International Nuclear Information System (INIS)

Smith, Michael S.; Roberts, Luke F.; Hix, W. Raphael; Bruner, Blake D.; Kozub, Raymond L.; Tytler, David; Fuller, George M.; Lingerfelt, Eric; Nesaraja, Caroline D.

2008-01-01

We performed new Big Bang Nucleosynthesis simulations with the bigbangonline.org suite of codes to determine, from the nuclear physics perspective, the highest achievable precision of the constraint on the baryon-to-photo ratio η given current observational uncertainties. We also performed sensitivity studies to determine the impact that particular nuclear physics measurements would have on the uncertainties of predicted abundances and on the η constraint

Big Bang Nucleosynthesis: Impact of Nuclear Physics Uncertainties on Baryonic Matter Density Constraints

International Nuclear Information System (INIS)

Smith, Michael Scott; Bruner, Blake D; KOZUB, RAYMOND L.; Roberts, Luke F.; Tytler, David; Fuller, George M.; Lingerfelt, Eric; Hix, William Raphael; Nesaraja, Caroline D

2008-01-01

We ran new Big Bang Nucleosynthesis simulations with the bigbangonline.org suite of codes to determine, from the nuclear physics perspective, the highest achievable precision of the constraint on the baryon-to-photo ratio eta given current observational uncertainties. We also ran sensitivity studies to determine the impact that particular nuclear physics measurements would have on the uncertainties of predicted abundances and on the eta constraint

Capture reactions on C-14 in nonstandard big bang nucleosynthesis

Science.gov (United States)

Wiescher, Michael; Gorres, Joachim; Thielemann, Friedrich-Karl

1990-01-01

Nonstandard big bang nucleosynthesis leads to the production of C-14. The further reaction path depends on the depletion of C-14 by either photon, alpha, or neutron capture reactions. The nucleus C-14 is of particular importance in these scenarios because it forms a bottleneck for the production of heavier nuclei A greater than 14. The reaction rates of all three capture reactions at big bang conditions are discussed, and it is shown that the resulting reaction path, leading to the production of heavier elements, is dominated by the (p, gamma) and (n, gamma) rates, contrary to earlier suggestions.

A tepid model for the early universe

International Nuclear Information System (INIS)

Carr, B.J.; Rees, M.J.

1977-01-01

If the Universe started off with a photon-to-baryon ratio much less than presently observed, massive black holes would have formed at early times even if the initial density fluctuations were very small. These holes could have generated the rest of the background radiation through accretion; in this way, such a Universe might automatically evolve to have the photon-to-baryon ratio observed today. This scenario could explain why the times of decoupling and matterradiation equilibrium are comparable and might provide a critical density of primordial black holes; it could also produce galaxies with black hole 'halos'. If the initial photon-to-baryon ratio was large enough, black hole formation would not occur: one would then have to invoke an alternative scenario in which the rest of the background radiation was generated by primordial stars at a comparatively recent epoch. (orig.) [de

A Physical – Geometrical Model of an Early Universe

Directory of Open Access Journals (Sweden)

Corneliu BERBENTE

2014-12-01

Full Text Available A physical-geometrical model for a possible early universe is proposed. One considers an initial singularity containing the energy of the whole universe. The singularity expands as a spherical wave at the speed of light generating space and time. The relations of the special theory of relativity, quantum mechanics and gas kinetics are considered applicable. A structuring of the primary wave is adopted on reasons of geometrical simplicity as well as on satisfying the conservation laws. The evolution is able to lead to particles very close to neutrons as mass and radius. The actually admitted values for the radius and mass of the universe as well as the temperature of the ground radiation (3-5 K can be obtained by using the proposed model.

Feedback in low-mass galaxies in the early Universe.

Science.gov (United States)

Erb, Dawn K

2015-07-09

The formation, evolution and death of massive stars release large quantities of energy and momentum into the gas surrounding the sites of star formation. This process, generically termed 'feedback', inhibits further star formation either by removing gas from the galaxy, or by heating it to temperatures that are too high to form new stars. Observations reveal feedback in the form of galactic-scale outflows of gas in galaxies with high rates of star formation, especially in the early Universe. Feedback in faint, low-mass galaxies probably facilitated the escape of ionizing radiation from galaxies when the Universe was about 500 million years old, so that the hydrogen between galaxies changed from neutral to ionized-the last major phase transition in the Universe.

Brane gases in the early Universe

International Nuclear Information System (INIS)

Alexander, S.; Brandenberger, R.; Easson, D.

2000-01-01

Over the past decade it has become clear that fundamental strings are not the only fundamental degrees of freedom in string theory. D-branes are also part of the spectrum of fundamental states. In this paper we explore some possible effects of D-branes on early Universe string cosmology, starting with two key assumptions: firstly that the initial state of the Universe corresponded to a dense, hot gas in which all degrees of freedom were in thermal equilibrium, and secondly that the topology of the background space admits one-cycles. We argue by t duality that in this context the cosmological singularities are not present. We derive the equation of state of the brane gases and apply the results to suggest that, in an expanding background, the winding modes of fundamental strings will play the most important role at late times. In particular, we argue that the string winding modes will only allow four space-time dimensions to become large. The presence of brane winding modes with p>1 may lead to a hierarchy in the sizes of the extra dimensions

Quantum theories of the early universe - a critical appraisal

International Nuclear Information System (INIS)

Hu, B.L.

1988-01-01

A critical appraisal of certain general problems in the study of quantum processes in curved space as applied to the construction of theories of the early universe is presented. Outstanding issues in different cosmological models and the degree of success of different quantum processes in addressing these issues are summarized. (author)

Spallation nucleosynthesis by accelerated charged-particles

International Nuclear Information System (INIS)

Goriely, S.

2008-01-01

Recent observations have suggested the presence of radioactive elements, such as Pm and 84≤Z≤99 elements) at the surface of the magnetic star HD101065, also known as Przybylski's star. This star is know to be a chemically peculiar star and its anomalous 38 30 heavy elements can be achieved. In this nucleosynthesis process, the secondary-neutron captures play a crucial role. The most attractive feature of the spallation process is the systematic production of Pm and Tc and the possible synthesis of actinides and sub-actinides.Based on such a parametric model, it is also shown that intense fluences of accelerated charged-particles interacting with surrounding material can efficiently produce elements heavier than iron. Different regimes are investigated and shown to be at the origin of p- and s-nuclei in the case of high-fluence low-flux events and r-nuclei for high-fluence high-flux irradiations. The possible existence of such irradiation events need to be confirmed by hydrodynamics simulations, but most of all by spectroscopic observations through the detection of short-lived radio-elements

Distortions in the cosmic background radiation and big-bang 4He nucleosynthesis

International Nuclear Information System (INIS)

Mathews, G.J.; Alhassid, Y.; Fuller, G.M.

1981-01-01

The observed distortion of the cosmic background radiation is analyzed in the framework of information theory to derive a simple form of the photon occupation probability. Taking this distribution function as indicative of the Lagrange parameters which might characterize the era of nucleosynthesis during the big bang, and assuming equilibrium among the constituents present, we find that the primordial 4 He abundance may be reduced by as much as 15% from the standard big-bang prediction

The quark gluon plasma equation of state and the expansion of the early Universe

International Nuclear Information System (INIS)

Sanches, S.M.; Navarra, F.S.; Fogaça, D.A.

2015-01-01

Our knowledge of the equation of state of the quark gluon plasma has been continuously growing due to the experimental results from heavy ion collisions, due to recent astrophysical measurements and also due to the advances in lattice QCD calculations. The new findings about this state may have consequences on the time evolution of the early Universe, which can be estimated by solving the Friedmann equations. The solutions of these equations give the time evolution of the energy density and also of the temperature in the beginning of the Universe. In this work we compute the time evolution of the QGP in the early Universe, comparing several equations of state, some of them based on the MIT bag model (and on its variants) and some of them based on lattice QCD calculations. Among other things, we investigate the effects of a finite baryon chemical potential in the evolution of the early Universe

Nucleosynthesis in neutrino-driven, aspherical supernova explosion of a massive star

International Nuclear Information System (INIS)

Fujimoto, S.; Hashimoto, M.; Ono, M.; Kotake, K.; Ohnishi, N.

2011-01-01

We examine explosive nucleosynthesis of p-nuclei during a delayed neutrino-driven, aspherical supernova explosion aided by standing accretion shock instability, based on two-dimensional hydrodynamic simulations of the explosion of a 15M · star. We find that p-nuclei are mainly produced through γ-processes, and that the nuclei lighter than 92 Mo are abundantly synthesized in slightly neutron-rich bubbles with electron fractions of Y e ≤0.48. 94 Mo, 96 Ru, and 98 Ru, are underproduced compared with the solar system, as in the spherical model.

Exploring the Early Universe on Mobile Devices

Science.gov (United States)

Kocevski, Dale; McGrath, E. J.; CANDELS Collaboration

2014-01-01

The widespread adoption of smart phones and tablet computers has the potential to revolutionize the way in which educational material is shared with the general public. As part of the outreach effort for the CANDELS survey, we have developed a free interactive astronomy education application named Hubble Universe for iPad and iPhone devices. The application focuses on extragalactic science topics related to the CANDELS legacy survey, which is documenting galaxy evolution in the early universe. I will provide an overview of the application, which contains a wide range of interactive content, including 3D models of astrophysical phenomenon, informative diagrams and computer simulations. I will discuss how the application can be used to enhance classroom learning both by providing a database of interactive media and by encouraging students to explore astronomical topics away from traditional settings like the classroom or the desktop computer.

Chaotic Universe, Friedmannian on the average. Pt. 2

Energy Technology Data Exchange (ETDEWEB)

Marochnik, L S [Rostovskij-na-Donu Gosudarstvennyj Univ. (USSR). Astrofizicheskoe Otdelenie

1980-05-01

On the basis of the solutions obtained in the previous paper, the changes in the scenario of the standard model of the Big Bang are found. The chaos degree (constraints on fluctuation spectra) is obtained, which could be still preserved by the initially completely chaotic Universe at the time of light elements nucleosynthesis tsub(es). The time boundaries of hadron and lepton eras and the time the electron neutrinos and neutrons become 'frozen' in reactions of weak interaction may be shifted up to 1.4 times. The corresponding temperatures may shift off from the standard ones 0.88 times if the mean-square level of fluctuations is close to unity. If the density of the energy of fluctuations concentrated in the short-wave region of the spectrum is less than 1.5 epsilon, the nucleosynthesis leads to a helium abundance coinciding with the observed one. If at the time tsub(es) the maximum of the spectral density of the energy is in the long-wave region, that is lambdasub(max) >>ctsub(es) the level of the chaos during the period of nucleosynthesis is restricted to ..nu.. approx. < 1.76 (where ..nu.. approx. ..integral../Csub(K)//sup 2/d/sup 3/K, Csub(K) is Fourier component of the amplitude of metric fluctuations). In particular, the protogalactic vortical disturbances with a wide spectrum ..delta.. approx. > 4 x 10/sup 3/ ..cap omega../sup -1/(..delta.. = ..delta.. K/K, ..cap omega.. = rho/rhosub(crit)) are compatible with the observed helium abundance.

Baryogenesis, dark matter and the maximal temperature of the early universe

Energy Technology Data Exchange (ETDEWEB)

Buchmueller, Wilfried

2012-12-15

Mechanisms for the generation of the matter-antimatter asymmetry and dark matter strongly depend on the reheating temperature T{sub R}, the maximal temperature reached in the early universe. Forthcoming results from the LHC, low energy experiments, astrophysical observations and the Planck satellite will significantly constrain baryogenesis and the nature of dark matter, and thereby provide valuable information about the very early hot universe. At present, a wide range of reheating temperatures is still consistent with observations. We illustrate possible origins of matter and dark matter with four examples: moduli decay, electroweak baryogenesis, leptogenesis in the {nu}MSM and thermal leptogenesis. Finally, we discuss the connection between baryogenesis, dark matter and inflation in the context of supersymmetric spontaneous B-L breaking.

Baryogenesis, dark matter and the maximal temperature of the early universe

International Nuclear Information System (INIS)

Buchmueller, Wilfried

2012-12-01

Mechanisms for the generation of the matter-antimatter asymmetry and dark matter strongly depend on the reheating temperature T R , the maximal temperature reached in the early universe. Forthcoming results from the LHC, low energy experiments, astrophysical observations and the Planck satellite will significantly constrain baryogenesis and the nature of dark matter, and thereby provide valuable information about the very early hot universe. At present, a wide range of reheating temperatures is still consistent with observations. We illustrate possible origins of matter and dark matter with four examples: moduli decay, electroweak baryogenesis, leptogenesis in the νMSM and thermal leptogenesis. Finally, we discuss the connection between baryogenesis, dark matter and inflation in the context of supersymmetric spontaneous B-L breaking.

The r-process nucleosynthesis: Nuclear physics challenges

Energy Technology Data Exchange (ETDEWEB)

Goriely, S. [Institut d' Astronomie et d' Astrophysique, Universite Libre de Bruxelles Campus de la Plaine, CP 226, 1050 Brussels (Belgium)

2012-10-20

About half of the nuclei heavier than iron observed in nature are produced by the socalled rapid neutron capture process, or r-process, of nucleosynthesis. The identification of the astrophysics site and the specific conditions in which the r-process takes place remains, however, one of the still-unsolved mysteries of modern astrophysics. Another underlying difficulty associated with our understanding of the r-process concerns the uncertainties in the predictions of nuclear properties for the few thousands exotic neutron-rich nuclei involved and for which essentially no experimental data exist. The present contribution emphasizes some important future challenges faced by nuclear physics in this problem, particularly in the determination of the nuclear structure properties of exotic neutron-rich nuclei as well as their radiative neutron capture rates and their fission probabilities. These quantities are particularly relevant to determine the composition of the matter resulting from the r-process. Their impact on the r-abundance distribution resulting from the decompression of neutron star matter is discussed.

GUTs and supersymmetric GUTs in the very early universe

International Nuclear Information System (INIS)

Ellis, J.

1983-01-01

This talk is intended as background material for many of the other talks treating the possible applications of GUTs to the very early universe. It starts with a review of the present theoretical and phenomenological status of GUTs and then goes on to raise some new issues for their prospective cosmological applications which arise in supersymmetric (susy) GUTs. (author)

The cosmological slingshot scenario: a stringy early times universe

Energy Technology Data Exchange (ETDEWEB)

Germani, Cristiano [D.A.M.T.P., Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Grandi, Nicolas [SISSA, via Beirut 4, 34014 Trieste (Italy); Kehagias, Alex [Physics Division, National Technical University of Athens, 15780 Zografou Campus, Athens (Greece)], E-mail: Germani@sissa.it, E-mail: grandi@fisica.unlp.edu.ar, E-mail: kehagias@central.ntua.gr

2008-07-07

A cosmological model for the early time universe is proposed. In this model, the universe is a wandering brane moving in a warped throat of a Calabi-Yau space. A nonzero angular momentum induces a turning point in the brane trajectory, and leads to a bouncing cosmology as experienced by an observer living on the brane. The universe undergoes a decelerated contraction followed by an accelerating expansion and no big-bang singularity. Although the number of e-folds of accelerated motion is low (less than 2), standard cosmological problems are not present in our model; thanks to the absence of an initial singularity and the violation of energy conditions of mirage matter at high energies. Density perturbations are also calculated in our model and we find a slightly red spectral index with negligible tensorial perturbations in compatibility with WMAP data.

Evidence for a vanishing ⁶Li/⁷Li isotopic signature in the metal-poor halo star HD84937

DEFF Research Database (Denmark)

Lind, K.; Asplund, M.; Collet, Remo

2012-01-01

The claimed detections of 6Li in the atmospheres of some metal-poor halo stars have lead to speculative additions to the standard model of Big Bang nucleosynthesis and the early Universe, as the inferred abundances cannot be explained by Galactic cosmic ray production. A prominent example of a so...

Social anxiety and negative early life events in university students.

Science.gov (United States)

Binelli, Cynthia; Ortiz, Ana; Muñiz, Armando; Gelabert, Estel; Ferraz, Liliana; S Filho, Alaor; Crippa, José Alexandre S; Nardi, Antonio E; Subirà, Susana; Martín-Santos, Rocío

2012-06-01

There is substantial evidence regarding the impact of negative life events during childhood on the aetiology of psychiatric disorders. We examined the association between negative early life events and social anxiety in a sample of 571 Spanish University students. In a cross-sectional survey conducted in 2007, we collected data through a semistructured questionnaire of sociodemographic variables, personal and family psychiatric history, and substance abuse. We assessed the five early negative life events: (i) the loss of someone close, (ii) emotional abuse, (iii) physical abuse, (iv) family violence, and (v) sexual abuse. All participants completed the Liebowitz Social Anxiety Scale. Mean (SD) age was 21 (4.5), 75% female, LSAS score was 40 (DP = 22), 14.2% had a psychiatric family history and 50.6% had negative life events during childhood. Linear regression analyses, after controlling for age, gender, and family psychiatric history, showed a positive association between family violence and social score (p = 0.03). None of the remaining stressors produced a significant increase in LSAS score (p > 0.05). University students with high levels of social anxiety presented higher prevalence of negative early life events. Thus, childhood family violence could be a risk factor for social anxiety in such a population.

Lithium isotopic abundances in metal-poor stars: a problem for standard big bang nucleosynthesis?

International Nuclear Information System (INIS)

Nissen, P.E.; Asplund, M.; Lambert, D.L.; Primas, F.; Smith, V.V.

2005-01-01

Spectral obtained with VLT/UVES suggest the existence of the 6 Li isotope in several metal-poor stars at a level that challenges ideas about its synthesis. The 7 Li abundance is, on the other hand, a factor of three lower than predicted by standard Big Bang nucleosynthesis theory. Both problems may be explained if decaying suppersymmetric particles affect the synthesis of light elements in the Big Bang. (orig.)

Supernova neutrinos and explosive nucleosynthesis

Science.gov (United States)

Kajino, T.; Aoki, W.; Cheoun, M.-K.; Hayakawa, T.; Hidaka, J.; Hirai, Y.; Mathews, G. J.; Nakamura, K.; Shibagaki, S.; Suzuki, T.

2014-05-01

Core-collapse supernovae eject huge amount of flux of energetic neutrinos. We studied the explosive nucleosyn-thesis in supernovae and found that several isotopes 7Li, 11B, 92Nb, 138La and 180Ta as well as r-process nuclei are affected by the neutrino interactions. The abundance of these isotopes therefore depends strongly on the neutrino flavor oscillation due to the Mikheyev-Smirnov-Wolfenstein (MSW) effect. We discuss first how to determine the neutrino temperatures in order to explain the observed solar system abundances of these isotopes, combined with Galactic chemical evolution of the light nuclei and the heavy r-process elements. We then study the effects of neutrino oscillation on their abundances, and propose a novel method to determine the still unknown neutrino oscillation parameters, mass hierarchy and θ13, simultaneously. There is recent evidence that SiC X grains from the Murchison meteorite may contain supernova-produced light elements 11B and 7Li encapsulated in the presolar grains. Combining the recent experimental constraints on θ13, we show that our method sug-gests at a marginal preference for an inverted neutrino mass hierarchy. Finally, we discuss supernova relic neutrinos that may indicate the softness of the equation of state (EoS) of nuclear matter as well as adiabatic conditions of the neutrino oscillation.

Supernova neutrinos and explosive nucleosynthesis

Energy Technology Data Exchange (ETDEWEB)

Kajino, T. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan and Department of Astronomy, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033 (Japan); Aoki, W. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Cheoun, M.-K. [Department of Physics, Soongsil University, Seoul 156-743 (Korea, Republic of); Hayakawa, T. [Japan Atomic Energy Agency, Shirakara-Shirane 2-4, Tokai-mura, Ibaraki 319-1195 (Japan); Hidaka, J.; Hirai, Y.; Shibagaki, S. [National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Mathews, G. J. [Center for Astrophysics, Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Nakamura, K. [Faculty of Science and Engineering, Waseda University, Ohkubo 3-4-1, Shinjuku, Tokyo 169-8555 (Japan); Suzuki, T. [Department of Physics, College of Humanities and Sciences, Nihon University, Sakurajosui 3-25-40, Setagaya-ku, Tokyo 156-8550 (Japan)

2014-05-09

Core-collapse supernovae eject huge amount of flux of energetic neutrinos. We studied the explosive nucleosyn-thesis in supernovae and found that several isotopes {sup 7}Li, {sup 11}B, {sup 92}Nb, {sup 138}La and {sup 180}Ta as well as r-process nuclei are affected by the neutrino interactions. The abundance of these isotopes therefore depends strongly on the neutrino flavor oscillation due to the Mikheyev-Smirnov-Wolfenstein (MSW) effect. We discuss first how to determine the neutrino temperatures in order to explain the observed solar system abundances of these isotopes, combined with Galactic chemical evolution of the light nuclei and the heavy r-process elements. We then study the effects of neutrino oscillation on their abundances, and propose a novel method to determine the still unknown neutrino oscillation parameters, mass hierarchy and θ{sub 13}, simultaneously. There is recent evidence that SiC X grains from the Murchison meteorite may contain supernova-produced light elements {sup 11}B and {sup 7}Li encapsulated in the presolar grains. Combining the recent experimental constraints on θ{sub 13}, we show that our method sug-gests at a marginal preference for an inverted neutrino mass hierarchy. Finally, we discuss supernova relic neutrinos that may indicate the softness of the equation of state (EoS) of nuclear matter as well as adiabatic conditions of the neutrino oscillation.

Gravitino in the early Universe. A model of extra-dimension and a model of dark matter; Gravitino dans l'Univers primordial: un modele d'extra-dimension et de matiere noire

Energy Technology Data Exchange (ETDEWEB)

Gherson, D

2007-10-15

This work can be related to the Horava-Witten M-theory in which the Universe could appear 5 dimensional at a stage of its evolution but also to theories of Baryogenesis through Lepto-genesis which imply high reheating temperatures after Inflation. The studied cosmological model is within the framework of a 5 dimensional supergravity with the extra-dimension compactified on an orbifold circle, where the matter and gauge field are located on one of the two branes localised at the orbifold fixed points and where the supergravity fields can propagate in the whole spatial dimensions. In the model, the Dark matter is made of neutralino which is supposed to be the lightest supersymmetric particle. We have shown that there are curves of constraints between the size of the extra-dimension and the reheating temperature of the Universe after Inflation. The constraints come from the measurements of the amount of Dark matter in the Universe and from the model of the Big Bang Nucleosynthesis of light elements. (author)

Particle theory, cosmology and relativity. Progress report, August 1, 1983-March 31, 1984

International Nuclear Information System (INIS)

Gaisser, T.K.; Steigman, G.

1983-01-01

Research progress is briefly described on the following topics: calculation of neutrino flux produced by cosmic rays, multiple muon events in deep underground detectors, large air showers, primordial nucleosynthesis, supersymmetry and equilibrium in the very early universe, the bag model of particle interactions, and particle theory in curved spaces. Publications are listed

A Universe without Weak Interactions

Energy Technology Data Exchange (ETDEWEB)

Harnik, Roni; Kribs, Graham D.; Perez, Gilad

2006-04-07

A universe without weak interactions is constructed that undergoes big-bang nucleosynthesis, matter domination, structure formation, and star formation. The stars in this universe are able to burn for billions of years, synthesize elements up to iron, and undergo supernova explosions, dispersing heavy elements into the interstellar medium. These definitive claims are supported by a detailed analysis where this hypothetical ''Weakless Universe'' is matched to our Universe by simultaneously adjusting Standard Model and cosmological parameters. For instance, chemistry and nuclear physics are essentially unchanged. The apparent habitability of the Weakless Universe suggests that the anthropic principle does not determine the scale of electroweak breaking, or even require that it be smaller than the Planck scale, so long as technically natural parameters may be suitably adjusted. Whether the multi-parameter adjustment is realized or probable is dependent on the ultraviolet completion, such as the string landscape. Considering a similar analysis for the cosmological constant, however, we argue that no adjustments of other parameters are able to allow the cosmological constant to raise up even remotely close to the Planck scale while obtaining macroscopic structure. The fine-tuning problems associated with the electroweak breaking scale and the cosmological constant therefore appear to be qualitatively different from the perspective of obtaining a habitable universe.

A Universe without Weak Interactions

International Nuclear Information System (INIS)

Harnik, R

2006-01-01

A universe without weak interactions is constructed that undergoes big-bang nucleosynthesis, matter domination, structure formation, and star formation. The stars in this universe are able to burn for billions of years, synthesize elements up to iron, and undergo supernova explosions, dispersing heavy elements into the interstellar medium. These definitive claims are supported by a detailed analysis where this hypothetical ''Weakless Universe'' is matched to our Universe by simultaneously adjusting Standard Model and cosmological parameters. For instance, chemistry and nuclear physics are essentially unchanged. The apparent habitability of the Weakless Universe suggests that the anthropic principle does not determine the scale of electroweak breaking, or even require that it be smaller than the Planck scale, so long as technically natural parameters may be suitably adjusted. Whether the multi-parameter adjustment is realized or probable is dependent on the ultraviolet completion, such as the string landscape. Considering a similar analysis for the cosmological constant, however, we argue that no adjustments of other parameters are able to allow the cosmological constant to raise up even remotely close to the Planck scale while obtaining macroscopic structure. The fine-tuning problems associated with the electroweak breaking scale and the cosmological constant therefore appear to be qualitatively different from the perspective of obtaining a habitable universe

A universe without weak interactions

International Nuclear Information System (INIS)

Harnik, Roni; Kribs, Graham D.; Perez, Gilad

2006-01-01

A universe without weak interactions is constructed that undergoes big-bang nucleosynthesis, matter domination, structure formation, and star formation. The stars in this universe are able to burn for billions of years, synthesize elements up to iron, and undergo supernova explosions, dispersing heavy elements into the interstellar medium. These definitive claims are supported by a detailed analysis where this hypothetical ''weakless universe'' is matched to our Universe by simultaneously adjusting standard model and cosmological parameters. For instance, chemistry and nuclear physics are essentially unchanged. The apparent habitability of the weakless universe suggests that the anthropic principle does not determine the scale of electroweak breaking, or even require that it be smaller than the Planck scale, so long as technically natural parameters may be suitably adjusted. Whether the multiparameter adjustment is realized or probable is dependent on the ultraviolet completion, such as the string landscape. Considering a similar analysis for the cosmological constant, however, we argue that no adjustments of other parameters are able to allow the cosmological constant to raise up even remotely close to the Planck scale while obtaining macroscopic structure. The fine-tuning problems associated with the electroweak breaking scale and the cosmological constant therefore appear to be qualitatively different from the perspective of obtaining a habitable universe

(n,{gamma}) and (p,{gamma}) rates for s- and p-process nucleosynthesis

Energy Technology Data Exchange (ETDEWEB)

Kaeppeler, F [Forschungszentrum Karlsruhe, Karlsruhe (Germany)

1998-06-01

The late stages of stellar evolution are characterized by a series of nucleosynthesis events. With respect to the heavy elements, these are the s process associated with the helium burning layers in Red Giant stars as well as the r and p processes which occur in supernova explosions. In contrast to the explosive scenarios, the nuclear physics data for s-process studies can be determined in laboratory experiments as illustrated at few recent examples. The application of these techniques to measurements of relevance for the p process are also discussed. (orig.)

(n,γ) and (p,γ) rates for s- and p-process nucleosynthesis

International Nuclear Information System (INIS)

Kaeppeler, F.

1998-01-01

The late stages of stellar evolution are characterized by a series of nucleosynthesis events. With respect to the heavy elements, these are the s process associated with the helium burning layers in Red Giant stars as well as the r and p processes which occur in supernova explosions. In contrast to the explosive scenarios, the nuclear physics data for s-process studies can be determined in laboratory experiments as illustrated at few recent examples. The application of these techniques to measurements of relevance for the p process are also discussed. (orig.)

Encouraging entrepreneurship in university labs: Research activities, research outputs, and early doctorate careers

OpenAIRE

Roach, Michael

2017-01-01

This paper investigates how the encouragement of entrepreneurship within university research labs relates with research activities, research outputs, and early doctorate careers. Utilizing a panel survey of 6,840 science & engineering doctoral students at 39 R1 research universities, this study shows that entrepreneurship is widely encouraged across university research labs, ranging from 54% in biomedical engineering to 18% in particle physics, while only a small share of labs openly discoura...

Quark mass variation constraints from Big Bang nucleosynthesis

Energy Technology Data Exchange (ETDEWEB)

Bedaque, P; Luu, T; Platter, L

2010-12-13

We study the impact on the primordial abundances of light elements created of a variation of the quark masses at the time of Big Bang nucleosynthesis (BBN). In order to navigate through the particle and nuclear physics required to connect quark masses to binding energies and reaction rates in a model-independent way we use lattice QCD data and an hierarchy of effective field theories. We find that the measured {sup 4}He abundances put a bound of {delta}-1% {approx}< m{sub q}/m{sub 1} {approx}< 0.7%. The effect of quark mass variations on the deuterium abundances can be largely compensated by changes of the baryon-to-photon ratio {eta}. Including the bounds on the variation of {eta} coming from WMAP results and some additional assumptions narrows the range of allowed values of {delta}m{sub q}/m{sub q} somewhat.

The Origin of Dust in the Early Universe

Science.gov (United States)

Dwek, Eli

2011-01-01

In this talk I will describe the origin of dust in the early universe. I will be presenting observations of the spectral energy distribution of the galaxy J1148+5251, and present estimates of the dust mass in this high redshift (z=6.4) object. I will then discuss the origin of this dust, and the role of SN and AGB stars as dust sources, and the effect of SNRs on the destruction of dust in the interstellar medium of this galaxy.

Optimization of a high-yield, low-areal-density fusion product source at the National Ignition Facility with applications in nucleosynthesis experiments

Science.gov (United States)

Gatu Johnson, M.; Casey, D. T.; Hohenberger, M.; Zylstra, A. B.; Bacher, A.; Brune, C. R.; Bionta, R. M.; Craxton, R. S.; Ellison, C. L.; Farrell, M.; Frenje, J. A.; Garbett, W.; Garcia, E. M.; Grim, G. P.; Hartouni, E.; Hatarik, R.; Herrmann, H. W.; Hohensee, M.; Holunga, D. M.; Hoppe, M.; Jackson, M.; Kabadi, N.; Khan, S. F.; Kilkenny, J. D.; Kohut, T. R.; Lahmann, B.; Le, H. P.; Li, C. K.; Masse, L.; McKenty, P. W.; McNabb, D. P.; Nikroo, A.; Parham, T. G.; Parker, C. E.; Petrasso, R. D.; Pino, J.; Remington, B.; Rice, N. G.; Rinderknecht, H. G.; Rosenberg, M. J.; Sanchez, J.; Sayre, D. B.; Schoff, M. E.; Shuldberg, C. M.; Séguin, F. H.; Sio, H.; Walters, Z. B.; Whitley, H. D.

2018-05-01

Polar-direct-drive exploding pushers are used as a high-yield, low-areal-density fusion product source at the National Ignition Facility with applications including diagnostic calibration, nuclear security, backlighting, electron-ion equilibration, and nucleosynthesis-relevant experiments. In this paper, two different paths to improving the performance of this platform are explored: (i) optimizing the laser drive, and (ii) optimizing the target. While the present study is specifically geared towards nucleosynthesis experiments, the results are generally applicable. Example data from T2/3He-gas-filled implosions with trace deuterium are used to show that yield and ion temperature (Tion) from 1.6 mm-outer-diameter thin-glass-shell capsule implosions are improved at a set laser energy by switching from a ramped to a square laser pulse shape, and that increased laser energy further improves yield and Tion, although by factors lower than predicted by 1 D simulations. Using data from D2/3He-gas-filled implosions, yield at a set Tion is experimentally verified to increase with capsule size. Uniform D3He-proton spectra from 3 mm-outer-diameter CH shell implosions demonstrate the utility of this platform for studying charged-particle-producing reactions relevant to stellar nucleosynthesis.

Black holes and structure in an oscillating universe

International Nuclear Information System (INIS)

Saslaw, W.C.

1991-01-01

If black holes exist in the contracting phase of a closed universe, they will give rise to a pressure and entropy catastrophe. First, the black holes absorb all the radiation; then their apparent horizons merge, and coalesce with the cosmological apparent horizon. All external observers become internal observers. It is possible that the internal metric of some of the merging black holes will be contracting, and others expanding. I suggest here that the resulting violent inhomogeneities can lead to a re-expansion in a significant portion of the universe. Global re-expansion, prompted by the merging of black holes, may thus begin in a semi-classical rather than fully quantum gravitational era, at densities greater than those at which nucleosynthesis occurs. Surviving black holes and inhomogeneities could initiate the formation of structures such as galaxies in the 'new' universe. The behaviour of such an oscillating universe would differ in detail from cycle to cycle. (author)

Observing the Cosmic Microwave Background Radiation: A Unique Window on the Early Universe

Science.gov (United States)

Hinshaw, Gary; Fisher, Richard R. (Technical Monitor)

2001-01-01

The cosmic microwave background radiation is the remnant heat from the Big Bang. It provides us with a unique probe of conditions in the early universe, long before any organized structures had yet formed. The anisotropy in the radiation's brightness yields important clues about primordial structure and additionally provides a wealth of information about the physics,of the early universe. Within the framework of inflationary dark matter models observations of the anisotropy on sub-degree angular scales will reveal the signatures of acoustic oscillations of the photon-baryon fluid at a redshift of approx. 1100. The validity of inflationary models will be tested and, if agreement is found, accurate values for most of the key cosmological parameters will result. If disagreement is found, we will need to rethink our basic ideas about the physics of the early universe. I will present an overview of the physical processes at work in forming the anisotropy and discuss what we have already learned from current observations. I will conclude with a brief overview of the recently launched Microwave Anisotropy Probe (MAP) mission which will observe the anisotropy over the full sky with 0.21 degree angular resolution. At the time of this meeting, MAP will have just arrived at the L2 Lagrange point, marking the start of its observing campaign. The MAP hardware is being produced by Goddard in partnership with Princeton University.

Evolution, Nucleosynthesis, and Yields of Low-mass Asymptotic Giant Branch Stars at Different Metallicities. II. The FRUITY Database

Science.gov (United States)

Cristallo, S.; Piersanti, L.; Straniero, O.; Gallino, R.; Domínguez, I.; Abia, C.; Di Rico, G.; Quintini, M.; Bisterzo, S.

2011-12-01

By using updated stellar low-mass stars models, we systematically investigate the nucleosynthesis processes occurring in asymptotic giant branch (AGB) stars. In this paper, we present a database dedicated to the nucleosynthesis of AGB stars: FRANEC Repository of Updated Isotopic Tables & Yields (FRUITY). An interactive Web-based interface allows users to freely download the full (from H to Bi) isotopic composition, as it changes after each third dredge-up (TDU) episode and the stellar yields the models produce. A first set of AGB models, having masses in the range 1.5 3.0 and metallicities 1 × 10-3 <= Z <= 2 × 10-2, is discussed. For each model, a detailed description of the physical and the chemical evolution is provided. In particular, we illustrate the details of the s-process and we evaluate the theoretical uncertainties due to the parameterization adopted to model convection and mass loss. The resulting nucleosynthesis scenario is checked by comparing the theoretical [hs/ls] and [Pb/hs] ratios to those obtained from the available abundance analysis of s-enhanced stars. On the average, the variation with the metallicity of these spectroscopic indexes is well reproduced by theoretical models, although the predicted spread at a given metallicity is substantially smaller than the observed one. Possible explanations for such a difference are briefly discussed. An independent check of the TDU efficiency is provided by the C-stars luminosity function. Consequently, theoretical C-stars luminosity functions for the Galactic disk and the Magellanic Clouds have been derived. We generally find good agreement with observations.

Compton Composites Late in the Early Universe

Directory of Open Access Journals (Sweden)

Frederick Mayer

2014-07-01

Full Text Available Beginning roughly two hundred years after the big-bang, a tresino phase transition generated Compton-scale composite particles and converted most of the ordinary plasma baryons into new forms of dark matter. Our model consists of ordinary electrons and protons that have been bound into mostly undetectable forms. This picture provides an explanation of the composition and history of ordinary to dark matter conversion starting with, and maintaining, a critical density Universe. The tresino phase transition started the conversion of ordinary matter plasma into tresino-proton pairs prior to the the recombination era. We derive the appropriate Saha–Boltzmann equilibrium to determine the plasma composition throughout the phase transition and later. The baryon population is shown to be quickly modified from ordinary matter plasma prior to the transition to a small amount of ordinary matter and a much larger amount of dark matter after the transition. We describe the tresino phase transition and the origin, quantity and evolution of the dark matter as it takes place from late in the early Universe until the present.

Study of the supernova nucleosynthesis 40Ca(α,γ)44Ti reaction: progress report

International Nuclear Information System (INIS)

Nassar, H.; Paul, M.; Ghelberg, S.; Ofan, A.; Trubnikov, N.; Ben-Dov, Y.; Hass, M.; Nara Singh, B.S.

2005-01-01

We report on a study of the α-capture reaction on 40 Ca in the energy range relevant to supernova nucleosynthesis (T 9 ∼ 0.8-3). The experiment measures the overall yield of 44 Ti nuclei produced in an activation of a thick 4 He target by a 40 Ca beam. Preliminary results show a significantly stronger yield than observed in previous measurements in the range T 9 ∼ 1.5-3

The Transient High Energy Sky and Early Universe Surveyor (THESEUS)

Science.gov (United States)

Amati, Lorenzo; O'Brien, Paul T.; Götz, Diego

2016-07-01

The Transient High Energy Sky and Early Universe Surveyor (THESEUS) is a mission concept under development by a large international collaboration aimed at exploiting gamma-ray bursts for investigating the early Universe. The main scientific objectives of THESEUS include: investigating the star formation rate and metallicity evolution of the ISM and IGM up to redshift 9-10, detecting the first generation (pop III) of stars, studying the sources and physics of re-ionization, detecting the faint end of galaxies luminosity function. These goals will be achieved through a unique combination of instruments allowing GRB detection and arcmin localization over a broad FOV (more than 1sr) and an energy band extending from several MeVs down to 0.3 keV with unprecedented sensitivity, as well as on-board prompt (few minutes) follow-up with a 0.6m class IR telescope with both imaging and spectroscopic capabilities. Such instrumentation will also allow THESEUS to unveil and study the population of soft and sub-energetic GRBs, and, more in general, to perform monitoring and survey of the X-ray sky with unprecedented sensitivity.

Limits from primordial nucleosynthesis on the properties of massive neutral leptons

International Nuclear Information System (INIS)

Dicus, D.A.; Kolb, E.W.; Teplitz, V.L.; Wagoner, R.V.

1977-11-01

If there exist neutral leptons with masses in the range 50 eV to 5 GeV, they would have been present in thermal equilibrium in the early stages of the hot big bang. In the subsequent evolution of the universe, if their lifetime is sufficiently long, their mass dominated the energy density of the universe. The effect of their presence on the synthesis of elements in the early universe is considered. Of the observed primordial abundances, the helium abundance was found to be independent of their existence, but the deuterium abundance was found to be sufficiently sensitive to allow bounds to be placed on the mass, lifetime, and decay modes of any heavy neutrinos. In particular, on the basis of present best estimates of astrophysical parameters, previous radiative lifetime bounds on the order of months are reduced to bounds on the order of hours, and expand the range of masses for which no radiatively decaying massive neutral leptons are allowed, to 50 to 100 keV

Neutron-Capture Nucleosynthesis and the Chemical Evolution of Globular Clusters

Science.gov (United States)

Shingles, Luke J.

2015-09-01

Elements heavier than iron are almost entirely produced in stars through neutron captures and radioactive decays. Of these heavy elements, roughly half are produced by the slow neutron-capture process (s-process), which takes place under extended exposure to low neutron densities. Most of the s-process production occurs in stars with initial masses between roughly 0.8 and 8 solar masses (Msun), which evolve through the Asymptotic Giant Branch (AGB) phase. This thesis explores several topics related to AGB stars and the s-process, with a focus on comparing theoretical models to observations in the literature on planetary nebulae, post-AGB stars, and globular cluster stars. A recurring theme is the uncertainty of carbon-13-pocket formation, which is crucial for building accurate models of s-process nucleosynthesis. We first investigated whether neutron-capture reactions in AGB stars are the cause of the low sulphur abundances in planetary nebulae and post-AGB stars relative to the interstellar medium. Accounting for uncertainties in the size of the partial mixing zone that forms carbon-13 pockets and the rates of neutron-capture and neutron-producing reactions, our models failed to reproduce the observed levels of sulphur destruction. From this, we concluded that AGB nucleosynthesis is not the cause of the sulphur anomaly. We also discovered a new method to constrain the extent of the partial mixing zone using neon abundances in planetary nebulae. We next aimed to discover the stellar sites of the s-process enrichment in globular clusters that have inter- and intra-cluster variation, with the examples of M4 (relative to M5) and M22, respectively. Using a new chemical evolution code developed by the candidate, we tested models with stellar yields from rotating massive stars and AGB stars. We compared our model predictions for the production of s-process elements with abundances from s-poor and s-rich populations. We found that rotating massive stars alone do not

Measurement of the cross section of the 8Li(d,α)6He reaction of possible relevance to big bang nucleosynthesis

International Nuclear Information System (INIS)

Sahin, L.; Boyd, R.N.; Cole, A.L.; Famiano, M.; Gueray, R.T.; Murphy, A. St.J.; Oezkan, N.; Kolata, J.J.; Guimaraes, V.; Hencheck, M.

2002-01-01

We report measurements of the cross section of the 8 Li(d,α) 6 He reaction in the energy range E c.m. =2.3-3.5 MeV using a 8 Li-radioactive beam on a CD 2 foil. The astrophysical S factor and reaction rate were calculated from the measured cross section. The 6 He nuclei produced in the reaction were detected in solid-state detector telescopes. This reaction might have affected the primordial abundance of 6 Li in big bang nucleosynthesis, since 6 He beta decays to 6 Li. However, several big bang nucleosynthesis network calculations were found to be insensitive to this reaction, suggesting that the 8 Li(d,α) 6 He reaction does not affect 6 Li primordial production

Big bang nucleosynthesis with Gaussian inhomogeneous neutrino degeneracy

International Nuclear Information System (INIS)

Stirling, Spencer D.; Scherrer, Robert J.

2002-01-01

We consider the effect of inhomogeneous neutrino degeneracy on big bang nucleosynthesis for the case where the distribution of neutrino chemical potentials is given by a Gaussian. The chemical potential fluctuations are taken to be isocurvature, so that only inhomogeneities in the electron chemical potential are relevant. Then the final element abundances are a function only of the baryon-photon ratio η, the effective number of additional neutrinos ΔN ν , the mean electron neutrino degeneracy parameter ξ-bar, and the rms fluctuation of the degeneracy parameter, σ ξ . We find that for fixed η, ΔN ν , and ξ-bar, the abundances of 4 He, D, and 7 Li are, in general, increasing functions of σ ξ . Hence, the effect of adding a Gaussian distribution for the electron neutrino degeneracy parameter is to decrease the allowed range for η. We show that this result can be generalized to a wide variety of distributions for ξ

r-process nucleosynthesis in dynamic helium-burning environments

International Nuclear Information System (INIS)

Cowan, J.J.; Cameron, A.G.W.; Truran, J.W.

1985-01-01

The results of an extended examination of r-process nucleosynthesis in helium-burning environments are presented. Using newly calculated nuclear rates, dynamical r-process calculations have been made of thermal runaways in helium cores typical of low-mass stars and in the helium zones of stars undergoing supernova explosions. These calculations show that, for a sufficient flux of neutrons produced by the 13 C neutron source, r-process nuclei in solar proportions can be produced. The conditions required for r-process production are found to be: 10 20 --10 21 neutrons cm -3 for times of 0.01--0.1 s and neutron number densities in excess of 10 19 cm -3 for times of approx.1 s. The amount of 13 C required is found to be exceedingly high: larger than is found to occur in any current stellar evolutionary model. It is thus unlikely that these helium-burning environments are responsible for producing the bulk of the r-process elements seen in the solar system

Early universe cosmology and tests of fundamental physics

International Nuclear Information System (INIS)

Albrecht, Andreas; Frieman, Joshua A.; Trodden, Mark

2002-01-01

This is the report of the Working Group on Early Universe Cosmology and tests of Fundamental Physics, group P4.8 of the of the Snowmass 2001 conference. Here we summarize the impressive array of advances that have taken place in this field, and identify opportunities for even greater progress in the future. Topics include Dark Energy, Cosmic Acceleration, Inflation, Phase Transitions, Baryogenesis, and String/M-theory Cosmology. The introductory section gives an executive summary with six key open questions on which we can expect to make significant progress

The Revival of Galactic Cosmic-Ray Nucleosynthesis?

International Nuclear Information System (INIS)

Fields, B.D.; Olive, K.A.

1999-01-01

Because of the roughly linear correlation between Be/H and Fe/H in low-metallicity halo stars, it has been argued that a open-quotes primaryclose quotes component in the nucleosynthesis of Be must be present in addition to the open-quotes secondaryclose quotes component from standard Galactic cosmic-ray nucleosynthesis. In this paper we critically reevaluate the evidence for the primary versus secondary character of Li, Be, and B (LiBeB) evolution, analyzing both the observations and Galactic chemical evolution models. Although it appears that [Be/H] versus [Fe/H] has a logarithmic slope near 1, it is rather the Be-O trend that directly arises from the physics of spallation production. Using new abundances for oxygen in halo stars based on UV OH lines, we find that in Population II stars for which O has been measured, the Be-O slope has a large uncertainty due to systematic effects. Namely, the Be-O logarithmic slope lies in the range 1.3 endash 1.8, rendering it difficult to distinguish from the data between the secondary slope of 2 and the primary slope of 1. The possible difference between the Be-Fe and Be-O slopes is a consequence of the variation in O/Fe versus Fe: recent data suggest that the best-fit O/Fe-Fe slope for Population II is in the range -0.5 to -0.2, rather than zero (i.e., Fe∝O) as is often assumed. In addition to this phenomenological analysis of Be and B evolution, we have also examined the predicted LiBeB, O, and Fe trends in Galactic chemical evolution models that include outflow. Based on our results, it is possible that a good fit to the LiBeB evolution requires only the traditional Galactic cosmic-ray spallation and the (primary) neutrino-process contribution to 11 B. We thus suggest that these two processes might be sufficient to explain 6 Li, Be, and B evolution in the Galaxy, without the need for an additional primary source of Be and B. However, the uncertainties in the data at this time prevent one from reaching a definitive

A Glimpse of the Very Early Universal Web

Science.gov (United States)

2001-05-01

The VLT Maps Extremely Distant Galaxies Summary New, trailblazing observations with the ESO Very Large Telescope (VLT) at Paranal lend strong support to current computer models of the early universe: It is "spongy", with galaxies forming along filaments, like droplets along the strands of a spiders web. A group of astronomers at ESO and in Denmark [1] determined the distances to some very faint galaxies in the neighbourhood of a distant quasar. Plotting their positions in a three-dimensional map, they found that these objects are located within a narrow "filament", exactly as predicted by the present theories for the development of the first structures in the young universe . The objects are most likely "building blocks" from which galaxies and clusters of galaxies assemble. This observation shows a very useful way forward for the study of the early evolution of the universe and the emergence of structures soon after the Big Bang. At the same time, it provides yet another proof of the great power of the new class of giant optical telescopes for cosmological studies. PR Photo 19a/01 : Web-like structures in the young Universe (computer model). PR Photo 19b/01 : A group of objects at redshift 3.04 . PR Photo 19c/01 : Animated view of sky field and distant filament . PR Photo 19d/01 : The shape of the filament . PR Photo 19e/01 : Artist's impression of the very distant filament. PR Video Clip 04/01 : Video animation of the very distant filament. The computers are ahead of the telescopes For the past two decades cosmologists have been in the somewhat odd situation that their computers were "ahead" of their telescopes. The rapid evolution of powerful computer hardware and sophisticated software has provided theorists with the ability to build almost any sort of virtual universe they can imagine. Starting with different initial conditions just after the Big Bang, they can watch such fictional worlds evolve over billions of years in their supercomputers - and do so in a

Probing the reheating temperature of the universe with a gravitational wave background

International Nuclear Information System (INIS)

Nakayama, Kazunori; Saito, Shun; Suwa, Yudai; Yokoyama, Jun'ichi

2008-01-01

The thermal history of the universe after big bang nucleosynthesis (BBN) is well understood both theoretically and observationally, and recent cosmological observations also begin to reveal the inflationary dynamics. However, the epoch between inflation and BBN is scarcely known. In this paper we show that the detection of the stochastic gravitational wave background around 1 Hz provides useful information about thermal history well before BBN. In particular, the reheating temperature of the universe may be determined by future space-based laser interferometer experiments such as DECIGO and/or BBO if it is around 10 6−9 GeV, depending on the tensor-to-scalar ratio r and dilution factor F

Electron-capture Rates for pf-shell Nuclei in Stellar Environments and Nucleosynthesis

Science.gov (United States)

Suzuki, Toshio; Honma, Michio; Mori, Kanji; Famiano, Michael A.; Kajino, Toshitaka; Hidakai, Jun; Otsuka, Takaharu

Gamow-Teller strengths in pf-shell nuclei obtained by a new shell-model Hamltonian, GXPF1J, are used to evaluate electron-capture rates in pf-shell nuclei at stellar environments. The nuclear weak rates with GXPF1J, which are generally smaller than previous evaluations for proton-rich nuclei, are applied to nucleosynthesis in type Ia supernova explosions. The updated rates are found to lead to less production of neutron-rich nuclei such as 58Ni and 54Cr, thus toward a solution of the problem of over-production of neutron-rich isotopes of iron-group nuclei compared to the solar abundance.

EVOLUTION, NUCLEOSYNTHESIS, AND YIELDS OF LOW-MASS ASYMPTOTIC GIANT BRANCH STARS AT DIFFERENT METALLICITIES. II. THE FRUITY DATABASE

International Nuclear Information System (INIS)

Cristallo, S.; Domínguez, I.; Abia, C.; Piersanti, L.; Straniero, O.; Gallino, R.; Di Rico, G.; Quintini, M.; Bisterzo, S.

2011-01-01

By using updated stellar low-mass stars models, we systematically investigate the nucleosynthesis processes occurring in asymptotic giant branch (AGB) stars. In this paper, we present a database dedicated to the nucleosynthesis of AGB stars: FRANEC Repository of Updated Isotopic Tables and Yields (FRUITY). An interactive Web-based interface allows users to freely download the full (from H to Bi) isotopic composition, as it changes after each third dredge-up (TDU) episode and the stellar yields the models produce. A first set of AGB models, having masses in the range 1.5 ≤M/M ☉ ≤ 3.0 and metallicities 1 × 10 –3 ≤ Z ≤ 2 × 10 –2 , is discussed. For each model, a detailed description of the physical and the chemical evolution is provided. In particular, we illustrate the details of the s-process and we evaluate the theoretical uncertainties due to the parameterization adopted to model convection and mass loss. The resulting nucleosynthesis scenario is checked by comparing the theoretical [hs/ls] and [Pb/hs] ratios to those obtained from the available abundance analysis of s-enhanced stars. On the average, the variation with the metallicity of these spectroscopic indexes is well reproduced by theoretical models, although the predicted spread at a given metallicity is substantially smaller than the observed one. Possible explanations for such a difference are briefly discussed. An independent check of the TDU efficiency is provided by the C-stars luminosity function. Consequently, theoretical C-stars luminosity functions for the Galactic disk and the Magellanic Clouds have been derived. We generally find good agreement with observations.

Solar neutrino spectrum, sterile neutrinos and additional radiation in the Universe

International Nuclear Information System (INIS)

Holanda, Pedro Cunha de

2011-01-01

Full text: Recent results from the SNO, Super-Kamiokande and Borexino experiments do not show the expected upturn of the energy spectrum of events (the ratio R ≡ N obs /N SSM ) at low energies. At the same time, cosmological observations testify for possible existence of additional relativistic degrees of freedom in the early Universe: ΔN eff = 1 - 2. These facts strengthen the case of very light sterile neutrino, ν s , with Δm 0 1 2 ∼ (0.7 - 2) . 10 -5 e V 2 , which mixes weakly with the active neutrinos. The ν s mixing in the mass eigenstate ν 1 characterized by sin 2 2∝ ∼ 10 -3 can explain an absence of the upturn. The mixing of ν s in the eigenstate ν 3 with sin 2 β ∼ 0.1 leads to production of ν s via oscillations in the Universe and to additional contribution Δ N eff ∼ 0.7 -1 before the big bang nucleosynthesis and later. Such a mixing can be tested in forthcoming experiments with the atmospheric neutrinos as well as in future accelerator long baseline experiments. It has substantial impact on conversion of the supernova neutrinos. We perform a qualitative and quantitative analysis of solar neutrino data including a fourth neutrino with different mixings with the active neutrino sector.(author)

On the creation of scalar particles in an early stage of the Friedmann closed-universe

International Nuclear Information System (INIS)

Ishihara, Hideki; Nariai, Hidekazu.

1982-03-01

Under impetus of the two experimental studies on neutrinos by Reines-group and Lyubimov's, it has been shown by Zel'dovich et al. that the cosmological universe is closed, provided that the neutrino masses m sub(#betta#sub(i)) (i = e, μ, tau) satisfy the inequality μ/i m sub(#betta#sub(i))c 2 >= 20 ev. In a previous paper, the senior author dealt with the creation of scalar particles in an expanding universe with non-flat 3-space, but the case of a closed universe was practically ignored owing to the situation that the positive frequency part (in the sense of the author) of a quantized scalar field is not well-defined in that universe. In view of these circumstances, the creation of scalar particles in an early stage of the Friedmann closed-universe is searched for, on the supposition that the Fulling condition is preferable to define the positive frequency part in question near the early stage (as well as the later one). (author)

Star Formation-Driven Winds in the Early Universe

Science.gov (United States)

Peek, Matthew; Lundgren, Britt; Brammer, Gabriel

2018-01-01

Measuring the extent of star formation-driven winds from galaxies in the early universe is crucial for understanding of how galaxies evolve over cosmic time. Using WFC3/IR grism data from the Hubble Space Telescope (HST), we have measured the star formation rates and star formation rate surface densities of several hundred galaxies at redshift (z) = 1, when the universe was roughly half its present age. The galaxies we examine are also probed by background quasars, whose spectra provide information about the extent of metal-enriched gas in their halos. We use a computational pipeline to measure the density of the star formation in each galaxy and correlate these measurements with detections of Mg II absorption in nearby quasar spectra from the Sloan Digital Sky Survey. Our preliminary results support a model in which galaxies with high SFR surface densities drive metal-enriched gas out of the disk and into these galaxies’ extended halos, where that gas is detected in the spectra of more distant quasars.

Thermodynamic fluctuations and the monopole density of the early Universe

International Nuclear Information System (INIS)

Diosi, L.; Lukacs, B.

1984-10-01

The probability of thermodynamic fluctuations is calculated by explicitly using the Riemannian structure of the thermodynamic state space. By means of this probability distribution, a correlation volume can be defined. Identifying this volume with one domain in the GUT continuum at the symmetry breaking phase transition in the early Universe, a prediction can be obtained for the primordial monopole density. (author)

James Gregory, the University observatory and the early acquisition of scientific instruments at the University of St Andrews

Science.gov (United States)

Rawson, Helen C.

2015-01-01

James Gregory, inventor of the reflecting telescope and Fellow of the Royal Society, was the first Regius Professor of Mathematics of the University of St Andrews, 1668–74. He attempted to establish in St Andrews what would, if completed, have been the first purpose-built observatory in the British Isles. He travelled to London in 1673 to purchase instruments for equipping the observatory and improving the teaching and study of natural philosophy and mathematics in the university, seeking the advice of John Flamsteed, later the first Astronomer Royal. This paper considers the observatory initiative and the early acquisition of instruments at the University of St Andrews, with reference to Gregory's correspondence, inventories made ca. 1699–ca. 1718 and extant instruments themselves, some of which predate Gregory's time. It examines the structure and fate of the university observatory, the legacy of Gregory's teaching and endeavours, and the meridian line laid down in 1748 in the University Library.

Implication of the Proton-Deuteron Radiative Capture for Big Bang Nucleosynthesis.

Science.gov (United States)

Marcucci, L E; Mangano, G; Kievsky, A; Viviani, M

2016-03-11

The astrophysical S factor for the radiative capture d(p,γ)^{3}He in the energy range of interest for big bang nucleosynthesis (BBN) is calculated using an ab initio approach. The nuclear Hamiltonian retains both two- and three-nucleon interactions-the Argonne v_{18} and the Urbana IX, respectively. Both one- and many-body contributions to the nuclear current operator are included. The former retain for the first time, besides the 1/m leading order contribution (m is the nucleon mass), also the next-to-leading order term, proportional to 1/m^{3}. The many-body currents are constructed in order to satisfy the current conservation relation with the adopted Hamiltonian model. The hyperspherical harmonics technique is applied to solve the A=3 bound and scattering states. Particular attention is paid in this second case in order to obtain, in the energy range of BBN, an uncertainty on the astrophysical S factor of the order or below ∼1%. Then, in this energy range, the S factor is found to be ∼10% larger than the currently adopted values. Part of this increase (1%-3%) is due to the 1/m^{3} one-body operator, while the remaining is due to the new more accurate scattering wave functions. We have studied the implication of this new determination for the d(p,γ)^{3}He S factor on the deuterium primordial abundance. We find that the predicted theoretical value for ^{2}H/H is in excellent agreement with its experimental determination, using the most recent determination of the baryon density of the Planck experiment, and with a standard number of relativistic degrees of freedom N_{eff}=3.046 during primordial nucleosynthesis. This calls for a more accurate measurement of the astrophysical S factor in order to confirm the present predictions.

THE ROLE OF DUST IN THE EARLY UNIVERSE. I. PROTOGALAXY EVOLUTION

International Nuclear Information System (INIS)

Yamasawa, Daisuke; Habe, Asao; Kozasa, Takashi; Nozawa, Takaya; Nomoto, Ken'ichi; Hirashita, Hiroyuki; Umeda, Hideyuki

2011-01-01

We develop one-zone galaxy formation models in the early universe, taking into account dust formation and evolution by supernova (SN) explosions. We focus on the time evolution of dust size distribution, because H 2 formation on the dust surface plays a critical role in the star formation process in the early universe. In the model, we assume that star formation rate (SFR) is proportional to the total amount of H 2 . We consistently treat (1) the formation and size evolution of dust, (2) the chemical reaction networks including H 2 formation both on the surface of dust and in gas phase, and (3) the SFR in the model. First, we find that, because of dust destruction due to both reverse and forward shocks driven by SNe, H 2 formation is more suppressed than in situations without such dust destruction. At the galaxy age of ∼0.8 Gyr, for galaxy models with virial mass M vir = 10 9 M sun and formation redshift z vir = 10, the molecular fraction is 2.5 orders of magnitude less in the model with dust destruction by both shocks than that in the model without dust destruction. Second, we show that the H 2 formation rate strongly depends on the interstellar medium (ISM) density around SN progenitors. The SFR in higher ISM density is lower, since dust destruction by reverse shocks is more effective in higher ISM density. We conclude that not only the amount but also the size distribution of dust related to star formation activity strongly affects the evolution of galaxies in the early universe.

Nuclear astrophysics: Recent results on CNO-cycle reactions and AGB nucleosynthesis

International Nuclear Information System (INIS)

La Cognata, M.

2011-01-01

Nuclear astrophysics aims to measure nuclear-reaction cross sections of astrophysical interest to be included into models to study stellar evolution and nucleosynthesis. Low energies, < 100 keV, are requested for this is the window where these processes are more effective. Two effects have prevented to achieve a satisfactory knowledge of the relevant nuclear processes, namely the Coulomb barrier exponentially suppressing the cross section and the presence of atomic electrons. These difficulties have triggered theoretical and experimental investigations to extend our knowledge down to astrophysical energies. For instance, indirect techniques such as the Trojan Horse Method and new experimental facilities such as deep underground laboratories have been devised yielding new cutting-edge results.

Inhomogeneous neutrino degeneracy and big bang nucleosynthesis

International Nuclear Information System (INIS)

Whitmire, Scott E.; Scherrer, Robert J.

2000-01-01

We examine big bang nucleosynthesis (BBN) in the case of inhomogeneous neutrino degeneracy, in the limit where the fluctuations are sufficiently small on large length scales that the present-day element abundances are homogeneous. We consider two representative cases: degeneracy of the electron neutrino alone and equal chemical potentials for all three neutrinos. We use a linear programming method to constrain an arbitrary distribution of the chemical potentials. For the current set of (highly restrictive) limits on the primordial element abundances, homogeneous neutrino degeneracy barely changes the allowed range of the baryon-to-photon ratio η. Inhomogeneous degeneracy allows for little change in the lower bound on η, but the upper bound in this case can be as large as η=1.1x10 -8 (only ν e degeneracy) or η=1.0x10 -9 (equal degeneracies for all three neutrinos). For the case of inhomogeneous neutrino degeneracy, we show that there is no BBN upper bound on the neutrino energy density, which is bounded in this case only by limits from structure formation and the cosmic microwave background. (c) 2000 The American Physical Society

Universal Design for Learning: Cognitive Theory into Practice for Facilitating Comprehension in Early Literacy

Science.gov (United States)

Brand, Susan Trostle; Dalton, Elizabeth M.

2012-01-01

Addressing the unique needs of children of all ages and abilities, Universal Design for Learning (UDL) is gaining momentum in schools and preschools around the nation and the globe. This article explores Universal Design for Learning and its promising applications to a variety of reading and language arts experiences in the Early Childhood…

The Early Astronomy Toolkit was Universal

Science.gov (United States)

Schaefer, Bradley E.

2018-01-01

From historical, anthropological, and archaeological records, we can reconstruct the general properties of the earliest astronomy for many cultures worldwide, and they all share many similar characteristics. The 'Early Astronomy Toolkit' (EAT) has the Earth being flat, and the heavens as a dome overhead populated by gods/heroes that rule Nature. The skies provided omens in a wide variety of manners, with eclipses, comets, and meteors always being evil and bad. Constellations were ubiquitous pictures of gods, heroes, animals, and everyday items; all for story telling. The calendars were all luni-solar, with no year counts and months only named by seasonal cues (including solstice observations and heliacal risings) with vague intercalation. Time of day came only from the sun's altitude/azimuth, while time at night came from star risings. Graves are oriented astronomically, and each culture has deep traditions of quartering the horizon. The most complicated astronomical tools were just a few sticks and stones. This is a higher level description and summary of the astronomy of all ancient cultures.This basic EAT was universal up until the Greeks, Mesopotamians, and Chinese broke out around 500 BC and afterwards. Outside the Eurasian milieu, with few exceptions (for example, planetary position measures in Mexico), this EAT represents astronomy for the rest of the world up until around 1600 AD. The EAT is present in these many cultures with virtually no variations or extensions. This universality must arise either from multiple independent inventions or by migration/diffusion. The probability of any culture independently inventing all 19 items in the EAT is low, but any such calculation has all the usual problems. Still, we realize that it is virtually impossible for many cultures to independently develop all 19 items in the EAT, so there must be a substantial fraction of migration of the early astronomical concepts. Further, the utter lack, as far as I know, of any

Generic features of vacuum phase transitions in the early universe

International Nuclear Information System (INIS)

Kephart, T.W.; Weiler, T.J.; Yuan, T.C.

1990-01-01

A simple Higgs model is utilized to show the occurrence of a four-phase pattern of vacuum symmetry. As temperature changes, an interplay of spontaneous symmetry breaking and spontaneous symmetry restoration ensues, and resonant field interchange occurs. The generality of models which may contain a sequence of vacuum phase transitions is emphasized. The laboratory for these multi-phase transitions is the early Universe. (orig.)

Nuclear data for unstable isotopes

International Nuclear Information System (INIS)

Sorlin, O.

1992-01-01

Nuclear Physics and Astrophysics are both entrusted with the task of understanding nucleosynthesis and energy production in the stars. At high temperatures and densities present in explosive scenarii such as the early universe, cataclysmic binary stars (nova or accretion stars), and supernovae, the nucleosynthesis proceeds throughout unstable nuclei. In order to produce and to study the most exotic isotopes that are not accessible from stable beam - stable (or radioactive) target experiments, it is necessary to develop facilities that utilize Radioactive Nuclear Beams (RNB). The existing methods for producing unstable nuclei will be described in paragraph 2. A review of the major explosive stellar processes will be made through some selected examples using RNB

Chaotic universe, Friedmann in the man. III. Ultrarelativistic matter, modified big bang, and constraints on disorder

Energy Technology Data Exchange (ETDEWEB)

Marochnik, L.S.

1981-01-01

The equations for the correlation functions (derived from the Einstein equations) that describe a statistically chaotic universe are solved in this paper as well as in Paper II. From these solutions the corresponding changes in the standard big bang scenario are determined, and the degree of disorder (that is, constaints on the fluctuation spectrum) which an initially wholly chaotic universe could have retained by the epoch t/sub es/ of light-element nucleosynthesis is established. The time boundaries of the hadron and lepton eras as well as the epochs when electron neutrinos and neutrons become frozen out in weak interactions shift by a factor of up to 1.4 compared with the standard model; the corresponding temperature will drop to 0.88 times the standard value if the rms level of fluctuations averaged over the spectrum during these eras is of order unity. If the fluctuations concentrated in the short-wavelength part of the spectrum have an energy density epsilon<1.5epsilon-bar, then nucleosynthesis in the chaotic cosmology would yield a helium abundance consistent with that observed. If at epoch t/sub es/ the spectral energy density peaks in the long-wave region (lambda/sub max/>>ct/sub es/), the degree of disorder during the nucleosynthesis era would be limited to ..nu..< or =1.76 (here ..nu..approx...integral..Vertical Barc/sub k/Vertical Bar/sup 2/d/sup 3/k; c/sub k/ represents the Fourier amplitude of the metric fluctuations). In particular, Ozernoi's protogalactic vortex perturbations with a wide spectrum (..delta.. = ..delta..k/k> or approx. =4 x 10/sup 3/..cap omega../sup -1/, ..cap omega.. = rho/rho/sub crit/) are compatible with the observed He abundance.

Evidence for multiple sources of 10Be in the early solar system

DEFF Research Database (Denmark)

Wielandt, Daniel Kim Peel; Nagashima, Kazuhide; Krot, Alexander N.

2012-01-01

Beryllium-10 is a short-lived radionuclide (t 1/2 = 1.4 Myr) uniquely synthesized by spallation reactions and inferred to have been present when the solar system's oldest solids (calcium-aluminum-rich inclusions, CAIs) formed. Yet, the astrophysical site of 10Be nucleosynthesis is uncertain. We...... in the gaseous CAI-forming reservoir, or in the inclusions themselves: this indicates at least two nucleosynthetic sources of 10Be in the early solar system. The most promising locale for 10Be synthesis is close to the proto-Sun during its early mass-accreting stages, as these are thought to coincide...

Cosmological QCD phase transition in steady non-equilibrium dissipative Hořava–Lifshitz early universe

International Nuclear Information System (INIS)

Khodadi, M.; Sepangi, H.R.

2014-01-01

We study the phase transition from quark–gluon plasma to hadrons in the early universe in the context of non-equilibrium thermodynamics. According to the standard model of cosmology, a phase transition associated with chiral symmetry breaking after the electro-weak transition has occurred when the universe was about 1–10 μs old. We focus attention on such a phase transition in the presence of a viscous relativistic cosmological background fluid in the framework of non-detailed balance Hořava–Lifshitz cosmology within an effective model of QCD. We consider a flat Friedmann–Robertson–Walker universe filled with a non-causal and a causal bulk viscous cosmological fluid respectively and investigate the effects of the running coupling constants of Hořava–Lifshitz gravity, λ, on the evolution of the physical quantities relevant to a description of the early universe, namely, the temperature T, scale factor a, deceleration parameter q and dimensionless ratio of the bulk viscosity coefficient to entropy density (ξ)/s . We assume that the bulk viscosity cosmological background fluid obeys the evolution equation of the steady truncated (Eckart) and full version of the Israel–Stewart fluid, respectively. -- Highlights: •In this paper we have studied quark–hadron phase transition in the early universe in the context of the Hořava–Lifshitz model. •We use a flat FRW universe with the bulk viscosity cosmological background fluid obeying the evolution equation of the steady truncated (Eckart) and full version of the Israel–Stewart fluid, respectively

Neutron Capture Cross Section of Unstable Ni63: Implications for Stellar Nucleosynthesis

Science.gov (United States)

Lederer, C.; Massimi, C.; Altstadt, S.; Andrzejewski, J.; Audouin, L.; Barbagallo, M.; Bécares, V.; Bečvář, F.; Belloni, F.; Berthoumieux, E.; Billowes, J.; Boccone, V.; Bosnar, D.; Brugger, M.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Carrapiço, C.; Cerutti, F.; Chiaveri, E.; Chin, M.; Colonna, N.; Cortés, G.; Cortés-Giraldo, M. A.; Diakaki, M.; Domingo-Pardo, C.; Duran, I.; Dressler, R.; Dzysiuk, N.; Eleftheriadis, C.; Ferrari, A.; Fraval, K.; Ganesan, S.; García, A. R.; Giubrone, G.; Gómez-Hornillos, M. B.; Gonçalves, I. F.; González-Romero, E.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Gurusamy, P.; Jenkins, D. G.; Jericha, E.; Kadi, Y.; Käppeler, F.; Karadimos, D.; Kivel, N.; Koehler, P.; Kokkoris, M.; Korschinek, G.; Krtička, M.; Kroll, J.; Langer, C.; Leeb, H.; Leong, L. S.; Losito, R.; Manousos, A.; Marganiec, J.; Martínez, T.; Mastinu, P. F.; Mastromarco, M.; Meaze, M.; Mendoza, E.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Mondelaers, W.; Paradela, C.; Pavlik, A.; Perkowski, J.; Pignatari, M.; Plompen, A.; Praena, J.; Quesada, J. M.; Rauscher, T.; Reifarth, R.; Riego, A.; Roman, F.; Rubbia, C.; Sarmento, R.; Schillebeeckx, P.; Schmidt, S.; Schumann, D.; Tagliente, G.; Tain, J. L.; Tarrío, D.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Versaci, R.; Vermeulen, M. J.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Ware, T.; Weigand, M.; Weiß, C.; Wright, T. J.; Žugec, P.

2013-01-01

The Ni63(n,γ) cross section has been measured for the first time at the neutron time-of-flight facility n_TOF at CERN from thermal neutron energies up to 200 keV. In total, capture kernels of 12 (new) resonances were determined. Maxwellian averaged cross sections were calculated for thermal energies from kT=5-100keV with uncertainties around 20%. Stellar model calculations for a 25M⊙ star show that the new data have a significant effect on the s-process production of Cu63, Ni64, and Zn64 in massive stars, allowing stronger constraints on the Cu yields from explosive nucleosynthesis in the subsequent supernova.

High-Temperature Nucleosynthesis Processes on the Proton-Rich Side of Stability: the Alpha-Rich Freezeout and the rp^2-Process

Science.gov (United States)

Meyer, Bradley S.

2001-10-01

Nucleosynthesis on the proton-rich side of stability has at least two intriguing aspects. First, the most abundant of the stable iron-group isotopes, such as ^48Ti, ^52Cr, and ^56,57Fe, are synthesized as proton-rich, radioactive parents in alpha-rich freezeouts from equilibrium. The production of these radioactive progenitors depends in large measure on reactions on the proton-rich side of stability. The second intriguing aspect is that explosive nucleosynthesis in a hydrogen-rich environment (namely, the rp-process) may be associated with exotic astrophysical settings, such as x-ray bursts, and may be responsible for production of some of the light p-process nuclei (for example, ^92,94Mo and ^96,98Ru). We have developed web-based tools to help nuclear physicists determine which nuclear reactions on the proton-rich side of stability govern the nucleosynthesis in these processes. For the alpha-rich freezeout, one may determine the effect of any one of 2,140 reactions on the yield of any isotope in the nuclear reaction network with the web calculator. As a relevant example, I will discuss the governing role of ^57Ni (n,p)^57Co in the synthesis of the important astronomical observable ^57Co. As for explosive, proton-rich burning, I will discuss the synthesis of p-process nuclei in the repetitive rp-process (the rp^2-process). movies/rp.html>Movies of the rp^2-process illustrate its important features and give some indications of the important nuclear reactions.

r-process nucleosynthesis in dynamic helium-burning environments

Science.gov (United States)

Cowan, J. J.; Cameron, A. G. W.; Truran, J. W.

1985-01-01

The results of an extended examination of r-process nucleosynthesis in helium-burning enviroments are presented. Using newly calculated nuclear rates, dynamical r-process calculations have been made of thermal runaways in helium cores typical of low-mass stars and in the helium zones of stars undergoing supernova explosions. These calculations show that, for a sufficient flux of neutrons produced by the C-13 neutron source, r-process nuclei in solar proportions can be produced. The conditions required for r-process production are found to be 10 to the 20th-10 to the 21st neutrons per cubic centimeter for times of 0.01-0.1 s and neutron number densities in excess of 10 to the 19th per cubic centimeter for times of about 1 s. The amount of C-13 required is found to be exceedingly high - larger than is found to occur in any current stellar evolutionary model. It is thus unlikely that these helium-burning environments are responsible for producing the bulk of the r-process elements seen in the solar system.

Introduction to Big Bang nucleosynthesis - Open and closed models, anisotropies

Science.gov (United States)

Tayler, R. J.

1982-10-01

A variety of observations suggest that the universe had a hot dense origin and that the pregalactic composition of the universe was determined by nuclear reactions that occurred in the first few minutes. There is no unique hot Big Bang theory, but the simplest version produces a primeval chemical composition that is in good qualitative agreement with the abundances deduced from observation. Whether or not any Big Bang theory will provide quantitative agreement with observations depends on a variety of factors in elementary particle physics (number and masses of stable or long-lived particles, half-life of neutron, structure of grand unified theories) and from observational astronomy (present mean baryon density of the universe, the Hubble constant and deceleration parameter). The influence of these factors on the abundances is discussed, as is the effect of departures from homogeneity and isotropy in the early universe.

Introduction to Big Bang nucleosynthesis: open and closed models, anisotropies

International Nuclear Information System (INIS)

Taylor, R.J.

1982-01-01

A variety of observations suggest that the Universe had a hot dense origin and that the pregalactic composition of the Universe was determined by nuclear reactions that occurred in the first few minutes. There is no unique hot Big Bang theory, but the simplest version produces a primeval chemical composition that is in good qualitative agreement with the abundances deduced from observation. Whether or not any Big Bang theory will provide quantitative agreement with observations depends on a variety of factors in elementary particle physics (number and masses of stable or long-lived particles, half-life of neutron, structure of grand unified theories) and from observational astronomy (present mean baryon density of the Universe, the Hubble constant and deceleration parameter). The influence of these factors on the abundances is discussed, as is the effect of departures from homogeneity and isotropy in the early Universe. (author)

Matter-antimatter separation in the early universe by rotating black holes

Science.gov (United States)

Leahy, D. A.

1981-01-01

Consideration of the effect of rotating black holes evaporating early in the universe shows that they would have produced oppositely directed neutrino and antineutrino currents, which push matter and antimatter apart. This separation mechanism is, however, too feeble to account for a present baryon-to-photon ratio of 10 to the -9th, and has no significant observational consequences.

AGB nucleosynthesis in the Large Magellanic Cloud. Detailed abundance analysis of the RV Tauri star MACHO 47.2496.8

NARCIS (Netherlands)

Reyniers, M.; Abia, C.; van Winckel, H.; Lloyd Evans, T.; Decin, L.K.E.; Eriksson, K.; Pollard, K.R.

2007-01-01

Context: .Abundance analysis of post-AGB objects as probes of AGB nucleosynthesis. Aims: .A detailed photospheric abundance study is performed on the carbon-rich post-AGB candidate MACHO 47.2496.8 in the LMC. Methods: .High-resolution, high signal-to-noise ESO VLT-UVES spectra of MACHO 47.2496.8 are

Current quests in nucleosynthesis: present and future neutron-induced reaction measurements

Directory of Open Access Journals (Sweden)

Praena J.

2014-03-01

Full Text Available We present some open questions in nucleosynthesis focused on the measurement of relevant neutron capture cross-sections and on new experimental methods. We review the recent 63Ni(n,γ experiment carried out at the n_TOF facility at CERN and its astrophysical implications as well as future experiments and opportunities at n_TOF. We argue some improvements in the measurement of cross-sections by activation arising from a new method for the generation of stellar neutron spectra. We show preliminary results of the experimental validation of the method. We discuss the astrophysical implications of the 181Ta(n,γ stellar cross-section measured with this method. Finally, we describe challenging experiments consisting of in situ radioactive ion beams and stellar neutron beams.

Anisotropic to Isotropic Phase Transitions in the Early Universe

Directory of Open Access Journals (Sweden)

Ajaib M. A.

2012-04-01

Full Text Available We attempt to develop a minimal formalism to describe an anisotropic to isotropic tran- sition in the early Universe. Assuming an underlying theory that violates Lorentz in- variance, we start with a Dirac like equation, involving four massless fields, and which does not exhibit Lorentz invariance. We then perform transformations that restore it to its covariant form along with a mass term for the fermion field. It is proposed that these transformations can be visualized as waves traveling in an anisotropic media. The trans- formation it = ℏ ! is then utilized to transit to a statistical thermodynamics system and the partition function then gives a better insight into the character of this transition. The statistical system hence realized is a two level system with each state doubly degenerate. We propose that modeling the transition this way can help explain the matter antimatter asymmetry of the Universe.

The Transient High-Energy Sky and Early Universe Surveyor (THESEUS)

Science.gov (United States)

Amati, L.; O'Brien, P.; Goetz, D.; Tenzer, C.; Bozzo, E.

2017-10-01

The Transient High Energy Sky and Early Universe Surveyor (THESEUS) is a mission concept developed by a large international collaboration aimed at exploiting Gamma-Ray Bursts for investigating the early Universe. The main scientic objectives of THESEUS, currently under evaluation by ESA within the selection process for next M5 mission, include: investigating the star formation rate and metallicity evolution of the ISM and IGM up to redshift 10, detecting the first generation (pop III) of stars, studying the sources and physics of re-ionization, detecting the faint end of galaxies luminosity function. These goals will be achieved through a unique combination of instruments allowing GRB detection and arcmin localization over a broad FOV (more than 1sr) and an energy band extending from several MeVs down to 0.3 keV with unprecedented sensitivity, as well as on-board prompt (few minutes) follow-up with a 0.7m class IR telescope with both imaging and spectroscopic capabilities. Such instrumentation will also allow THESEUS to perform a monitoring of the X-ray sky with unprecedented sensitivity, which will provide a perfect service and sinergy to next generation multi-wavalength (e.g., E-ELT, SKA, CTA, ATHENA) and multi-messenger (aLIGO, aVIRGO, eLISA, ET, neutrino detectors, ...) facilities.

Green's function for the scalar field in the early Universe

International Nuclear Information System (INIS)

Chowdhury, A.; Mallik, S.

1987-01-01

We derive the thermal Green's function for the scalar field in a de Sitter space-time and apply it to the problem of the early Universe. Field fluctuations relevant for inflation arise predominantly from wavelengths of the order of the inverse Hubble constant. Sufficient inflation is obtained in a Coleman-Weinberg model, provided the coupling constant is small enough. The results are insensitive to the choice of the vacuum of the field theory

Awareness of Skin Cancer, Prevention, and Early Detection among Turkish University Students

Directory of Open Access Journals (Sweden)

Ziyafet Ugurlu

2016-01-01

Full Text Available Objective: The aim of this study was to determine the awareness about skin cancer, prevention, and early detection among university students. Methods: This descriptive cross-sectional study was carried out with 404 students in a university located in Ankara, the capital city of Turkey. A 35-item questionnaire was used for data collection. Results: Less than half of the students (37.9% had knowledge about skin cancer mostly through the internet (24.5% and media (24.1%. Half of them aware of the risk factors; mostly as avoiding direct exposure to the Sun between 10 am and 4 pm (45.3%; smoking and alcohol (38.4%; having fair skin color (34.9%; and ultraviolet light exposure (25.7%. Only one-third of them (32.9% are knowledgeable about skin cancer signs and symptoms, such as a change in color and appearance of the nevus/moles (24%. The majority of the responders (77.3% did not know about screening tests for skin cancer and only 18 (4.5% students were practicing skin self-examination. Conclusions: This study showed a lack of knowledge about skin cancer, prevention, and early detection among university students and reported the need for educational interventions to raise awareness in this target group.

Simultaneous solution to the 6Li and 7Li big bang nucleosynthesis problems from a long-lived negatively charged leptonic particle

International Nuclear Information System (INIS)

Kusakabe, Motohiko; Kajino, Toshitaka; Boyd, Richard N.; Yoshida, Takashi; Mathews, Grant J.

2007-01-01

The 6 Li abundance observed in metal-poor halo stars exhibits a plateau similar to that for 7 Li suggesting a primordial origin. However, the observed abundance of 6 Li is a factor of 10 3 larger and that of 7 Li is a factor of 3 lower than the abundances predicted in the standard big bang when the baryon-to-photon ratio is fixed by Wilkinson microwave anisotropy probe. Here we show that both of these abundance anomalies can be explained by the existence of a long-lived massive, negatively charged leptonic particle during nucleosynthesis. Such particles would capture onto the synthesized nuclei thereby reducing the reaction Coulomb barriers and opening new transfer reaction possibilities, and catalyzing a second round of big bang nucleosynthesis. This novel solution to both of the Li problems can be achieved with or without the additional effects of stellar destruction

Understanding r-process nucleosynthesis with dwarf galaxies

Science.gov (United States)

Ji, Alexander P.

2018-06-01

The Milky Way's faintest dwarf galaxy satellites each sample short, independent bursts of star formation from the first 1-2 Gyr of the universe. Their simple formation history makes them ideal systems to understand how rare events like neutron star mergers contribute to early enrichment of r-process elements. I will focus on the ultra-faint galaxy Reticulum II, which experienced a single prolific r-process event that left ~80% of its stars extremely enriched in r-process elements. I will present abundances of ~40 elements derived from the highest signal-to-noise high-resolution spectrum ever taken for an ultra-faint dwarf galaxy star. Precise measurements of elements from all three r-process peaks reaffirm the universal nature of the r-process abundance pattern from Ba to Ir. The first r-process peak is significantly lower than solar but matches other r-process enhanced stars. This constrains the neutron-richness of r-process ejecta in neutron star mergers. The radioactive element thorium is detected with a somewhat low abundance. Naive application of currently predicted initial production ratios could imply an age >20 Gyr, but more likely indicates that the initial production ratios require revision. The abundance of lighter elements up to Zn are consistent with extremely metal-poor Milky Way halo stars. These elements may eventually provide a way to test for other hypothesized r-process sites, but only after a more detailed understanding of the chemical evolution in this galaxy. Reticulum II provides a clean view of early r-process enrichment that can be used to understand the increasing number of r-process measurements in other dwarf galaxies.

Neutrino mass and the origin of galactic magnetic fields

International Nuclear Information System (INIS)

Enqvist, K.; Semikoz, V.; Shukurov, A.; Sokoloff, D.

1993-01-01

We compare two constraints on the strength of the cosmological primordial magnetic field: the one following from the restrictions on the Dirac neutrino spin flip in the early Universe, and another one based on the galactic dynamo theory for the Milky Way (presuming that the seed magnetic field has a relic origin). Since the magnetic field facilitates transitions between left- and right-handed neutrino states, thereby affecting 4 He production at primordial nucleosynthesis, we can obtain a guaranteed upper limit on the strength of the relic magnetic field in the protogalaxy, B c approx-lt 4x10 -9 --3x10 -13 G, depending on the neutrino magnetic moment, if we adopt the MSW explanation of the GALLEX results. On the other hand, models of the dynamo in the Milky Way indicate that the seed magnetic field should be at least 10 -11 --10 -13 G at the protogalaxy scale L=100 kpc. These upper and lower limiting ranges are marginally consistent provided the electron neutrino mass is below 0.3 eV. The results apply to a relic magnetic field produced in the early Universe by any causal mechanism before the nucleosynthesis

Summary of Recent Developments in Primordial Nucleosynthesis.

Science.gov (United States)

Schramm, D N

1993-06-01

This paper summarizes the recent observational and theoretical results on Big Bang Nucleosynthesis. In particular, it is shown that the new Pop II (6)Li results strongly support the argument that the Spite Plateau lithium is a good estimate of the primordial value. The (6)Li is consistent with the Be and Be found in Pop II stars, assuming those elements are cosmic ray produced. The HST (2)D value tightens the (2)D arguments and the observation of the (3)He in planetary nebula strengthens the (3)He +(2)D argument as a lower bound on Ωb. The new low metalicity (4)He determinations slightly raise the best primordial (4)He number and thus make a better fit and avoid a potential problem. The quark-hadron inspired inhomogeneous calculations now unanimously agree that only relatively small variations in Ωb are possible vis-à-vis the homogeneous model; hence, the robustness of Ωb∼ 0.05 is now apparent. A comparison with the ROSAT cluster data is also shown to be consistent with the standard BBN model. Ωb∼ 1 seems to be definitely excluded, so, if Ω= 1, as some recent observations may hint, then non-baryonic dark matter is required.

The Lithium isotope ratio in Population II halo dwarfs: A proposed test of the late decaying massive particle nucleosynthesis scenario

International Nuclear Information System (INIS)

Brown, L.; Schramm, D.N.

1988-02-01

It is shown that observations of the Lithium isotope ratio in high surface temperature Population II stars may be critical to cosmological nucleosynthesis models. In particular, decaying particle scenarios as derived in some supersymmetric models may stand or fall with such observations. 15 refs., 3 figs., 2 tabs

S-process nucleosynthesis in low mass AGB Stars: do we really need an improved determination of the 13C(α, n)16O reaction rate?

International Nuclear Information System (INIS)

Cristallo, S.; Straniero, O.; Gallino, R.

2005-01-01

Thermally pulsing Asymptotic Giant Branch stars are responsible for the nucleosynthesis of the main component of the cosmic s-elements. The most important neutron source is the 13 C(α, n) 16 O reaction. Owing to the presence of a subthreshold resonance, the low energy extrapolation is a rather complex task. The rate quoted in the literature differ up to a factor of 4 at typical stellar energies. The latest improvements in computer power allows us to calculate the evolution of TP-AGB stars coupled with a full nuclear network, extending from hydrogen to lead. Here we discuss the effects of the variation of the 13 C(α, n) 16 O rate on the predicted neutron capture nucleosynthesis

Parastatistics and the equation of state for the early universe

International Nuclear Information System (INIS)

Aldrovandi, R.; Monte Lima, I. do.

1982-01-01

The equation of state for an ideal mixture of relativistic quantum gases obeying any (para-) statistics is given. Recursion formulas are obtained for the distribution functions and correlations are analysed. The equation of state can be applied to the early Universe, allowing the quarks to be treated either as coloured fermions of (unequivalently) as parafermions of order 3. In the latter case, a tendency to aggregate into triads by a mere statistical effect is exhibited. (Author) [pt

CP violations in the Universe

Science.gov (United States)

Auriemma, Giulio

2003-12-01

The origin of the asymmetry between matter and antimatter that is evident in our part of the Universe is one of the open questions in cosmology, because the CPT symmetry between matter and antimatter seems to be absolutely conserved at microscopic level. We repeat here the classical proofs which exclude the viability of a Universe baryon symmetric on the average, or the observed asymmetry as an initial conditions. The current understanding is that the asymmetry should have been dynamically generated before nucleosynthesis, by B, C, and CP violating processes, acting out of thermodynamical equilibrium, as suggested by Sakharov in the 70's. The physical realizations of these conditions would be possible, in principle, also in the framework of the Standard Model of elementary particles, but the present limits on the mass of the higgs particle exclude this possibility. Finally we present the model of baryogenesis through leptogenesis, which is allowed by a minimal extension of the Standard Model, which has the appeal of being testable in future long-baseline neutrino oscillation experiments.

The mass (charge) spectrum of superheavy nuclei fission fragments: the new perspectives for the theory of nucleosynthesis

International Nuclear Information System (INIS)

Maslyuk, V.T.

2012-01-01

A new approach to the problem of nucleosynthesis based on assumption of a nuclear matter or superheavy nuclei series fragmentation up to atomic nuclei is proposed. It is shown that studies of the mass (charge) fragments yields (MCFY) after nuclear matter disintegration is possible within proposed statistical theory. The data of MCFY calculation for exotic superheavy nuclei multifragmentation with A=300, 900 and 1200 and arbitrary Z values are demonstrated

Universal biology and the statistical mechanics of early life

Science.gov (United States)

Goldenfeld, Nigel; Biancalani, Tommaso; Jafarpour, Farshid

2017-11-01

All known life on the Earth exhibits at least two non-trivial common features: the canonical genetic code and biological homochirality, both of which emerged prior to the Last Universal Common Ancestor state. This article describes recent efforts to provide a narrative of this epoch using tools from statistical mechanics. During the emergence of self-replicating life far from equilibrium in a period of chemical evolution, minimal models of autocatalysis show that homochirality would have necessarily co-evolved along with the efficiency of early-life self-replicators. Dynamical system models of the evolution of the genetic code must explain its universality and its highly refined error-minimization properties. These have both been accounted for in a scenario where life arose from a collective, networked phase where there was no notion of species and perhaps even individuality itself. We show how this phase ultimately terminated during an event sometimes known as the Darwinian transition, leading to the present epoch of tree-like vertical descent of organismal lineages. These examples illustrate concrete examples of universal biology: the quest for a fundamental understanding of the basic properties of living systems, independent of precise instantiation in chemistry or other media. This article is part of the themed issue 'Reconceptualizing the origins of life'.

Astrophysical S-factor for destructive reactions of lithium-7 in big bang nucleosynthesis

Energy Technology Data Exchange (ETDEWEB)

Komatsubara, Tetsuro; Kwon, YoungKwan; Moon, JunYoung; Kim, Yong-Kyun [Rare Isotope Science Project, Institute for Basic Science, Daejeon (Korea, Republic of); Moon, Chang-Bum [Hoseo University, Asan, Chungnam (Korea, Republic of); Ozawa, Akira; Sasa, Kimikazu; Onishi, Takahiro; Yuasa, Toshiaki; Okada, Shunsuke; Saito, Yuta [Division of Physics, University of Tsukuba, Tsukuba, Ibaraki (Japan); Hayakawa, Takehito; Shizuma, Toshiyuki [Japan Atomic Energy Agency, Shirakata Shirane, Tokai, Ibaraki (Japan); Kubono, Shigeru [RIKEN, Hirosawa, Wako, Saitama (Japan); Kusakabe, Motohiko [School of Liberal Arts and Science, Korea Aerospace University (Korea, Republic of); Kajino, Toshitaka [National Astronomical Observatory, Osawa, Mitaka, Tokyo (Japan)

2014-05-02

One of the most prominent success with the Big Bang models is the precise reproduction of mass abundance ratio for {sup 4}He. In spite of the success, abundances of lithium isotopes are still inconsistent between observations and their calculated results, which is known as lithium abundance problem. Since the calculations were based on the experimental reaction data together with theoretical estimations, more precise experimental measurements may improve the knowledge of the Big Bang nucleosynthesis. As one of the destruction process of lithium-7, we have performed measurements for the reaction cross sections of the {sup 7}L({sup 3}He,p){sup 9}Be reaction.

Mass spectrometry of stardust : experimental tests of nucleosynthesis

International Nuclear Information System (INIS)

Clayton, R.N.

1997-01-01

Primitive meteorites contain grains of diamond, graphite and silicon carbide which condensed from the outflows of red-giant stars, which existed before the formation of our Sun and Solar System. Nuclear processes within the parent star have modified the isotopic compositions of all elements in the grains. By means of a very sensitive and selective microanalytical technique, Resonant Ionization Mass Spectrometry, we can measure isotopic abundances of trace metals in individual 3-micrometer-sized crystals. The technique uses multi-photon photoionization with tuned lasers to ionize a single element selectively and efficiently. This allows isotopic measurements of trace constituents in complex systems. Results from zirconium and molybdenum in presolar silicon carbide grains show large enhancements in the s-process isotopes, and depletion by factors >2 in the r-process and p-process isotopes. The observations are in good agreement with recent calculations of s-process nucleosynthesis in Asymptotic Giant Branch stars. These results confirm the classical subdivision of nucleo-synthetic processes into p-, r-, and s-processes and show that the principal site of the s-process is in carbon-rich red giant stars. (author)

Supernova nucleosynthesis and the physics of neutrino oscillation

Energy Technology Data Exchange (ETDEWEB)

Kajino, Toshitaka [National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan) and Department of Astronomy, Graduate School of Science, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033 (Japan)

2012-11-20

We studied the explosive nucleosynthesis in core-collapse supernovae and found that several isotopes of rare elements like {sup 7}Li, {sup 11}B, {sup 138}La, {sup 180}Ta and others are predominantly produced by the neutrino interactions with several abundant nuclei. These isotopes are strongly affected by the neutrino flavor oscillation due to the MSW (Mikheyev-Smirnov-Wolfenstein) effect. We here first study how to know the suitable average neutrino temperatures in order to explain the observed solar system abundances of these isotopes, combined with Galactic chemical evolution of the light nuclei and the heavy r-process elements. We then study the neutrino oscillation effects on their abundances, and propose a new novel method to determine the neutrino oscillation parameters, {theta}{sub 13} and mass hierarchy, simultaneously. There is recent evidence that some SiC X grains from the Murchison meteorite may contain supernova-produced neutrino-process {sup 11}B and {sup 7}Li encapsulated in the grains. Combining the recent experimental constraints on {theta}{sub 13}, we show that although the uncertainties are still large, our method hints at a marginal preference for an inverted neutrino mass hierarchy for the first time.

Supernova nucleosynthesis and the physics of neutrino oscillation

Science.gov (United States)

Kajino, Toshitaka

2012-11-01

We studied the explosive nucleosynthesis in core-collapse supernovae and found that several isotopes of rare elements like 7Li, 11B, 138La, 180Ta and others are predominantly produced by the neutrino interactions with several abundant nuclei. These isotopes are strongly affected by the neutrino flavor oscillation due to the MSW (Mikheyev-Smirnov-Wolfenstein) effect. We here first study how to know the suitable average neutrino temperatures in order to explain the observed solar system abundances of these isotopes, combined with Galactic chemical evolution of the light nuclei and the heavy r-process elements. We then study the neutrino oscillation effects on their abundances, and propose a new novel method to determine the neutrino oscillation parameters, θ13 and mass hierarchy, simultaneously. There is recent evidence that some SiC X grains from the Murchison meteorite may contain supernova-produced neutrino-process 11B and 7Li encapsulated in the grains. Combining the recent experimental constraints on θ13, we show that although the uncertainties are still large, our method hints at a marginal preference for an inverted neutrino mass hierarchy for the first time.

Study on the dominant reaction path in nucleosynthesis during stellar evolution by means of the Monte Carlo method

International Nuclear Information System (INIS)

Yamamoto, K.; Hashizume, K.; Wada, T.; Ohta, M.; Suda, T.; Nishimura, T.; Fujimoto, M. Y.; Kato, K.; Aikawa, M.

2006-01-01

We propose a Monte Carlo method to study the reaction paths in nucleosynthesis during stellar evolution. Determination of reaction paths is important to obtain the physical picture of stellar evolution. The combination of network calculation and our method gives us a better understanding of physical picture. We apply our method to the case of the helium shell flash model in the extremely metal poor star

The Role of Fe and Ni for S-process Nucleosynthesis and Innovative Nuclear Technologies

CERN Document Server

Giubrone, G; Perkowski, J; Andriamonje, S; Carrapico, C; Wallner, A; Vannini, G; Quesada, J M; Lederer, C; Tarrio, D; Berthier, B; Lozano, M; Krticka, M; Domingo-Pardo, C; Chiaveri, E; Jericha, E; Ferrari, A; Massimi, C; Avrigeanu, V; Martinez, T; Guerrero, C; Andrzejewski, J; Karadimos, D; Mendoza, E; Ganesan, S; Vlachoudis, V; Milazzo, P M; Cortes, G; Becares, V; Tain, J L; Variale, V; Quinones, J; Calvino, F; Kappeler, F; Gunsing, F; Gramegna, F; Colonna, N; Marrone, S; Lebbos, E; Paradela, C; Mastinu, P F; Vaz, P; Tassan-Got, L; Kadi, Y; Dillman, I; Cano-Ott, D; Brugger, M; Audouin, L; Fernandez-Ordonez, M; Sarmento, R; Becvar, F; Goncalves, I F; Martin-Fuertes, F; Cerutti, F; Pina, G; Mosconi, M; Tagliente, G; Duran, I; Berthoumieux, E; Praena, J; Ioannides, K; Weiss, C; Mirea, M; Gomez-Hornillos, M B; Vlastou, R; Calviani, M; Nolte, R; Mengoni, A; Gonzalez-Romero, E; Marganiec, J; Leeb, H; Heil, M; Meaze, M H; Pavlik, A; Belloni, F; Harrispopulos S

2011-01-01

The accurate measurement of neutron capture cross sections of all Fe and Ni isotopes is important for disentangling the contribution of the s-process and the r-process to the stellar nucleosynthesis of elements in the mass range 60 < A < 120. At the same time, Fe and Ni are important components of structural materials and improved neutron cross section data is relevant in the design of new nuclear systems. With the aim of obtaining improved capture data on all stable iron and nickel isotopes, a program of measurements has been launched at the CERN Neutron Time of Flight Facility n_TOF.

Vacuum stability in the early universe and the backreaction of classical gravity.

Science.gov (United States)

Markkanen, Tommi

2018-03-06

In the case of a metastable electroweak vacuum, the quantum corrected effective potential plays a crucial role in the potential instability of the standard model. In the early universe, in particular during inflation and reheating, this instability can be triggered leading to catastrophic vacuum decay. We discuss how the large space-time curvature of the early universe can be incorporated in the calculation and in many cases significantly modify the flat space prediction. The two key new elements are the unavoidable generation of the non-minimal coupling between the Higgs field and the scalar curvature of gravity and a curvature induced contribution to the running of the constants. For the minimal set up of the standard model and a decoupled inflation sector we show how a metastable vacuum can lead to very tight bounds for the non-minimal coupling. We also discuss a novel and very much related dark matter generation mechanism.This article is part of the Theo Murphy meeting issue 'Higgs cosmology'. © 2018 The Author(s).

Chaos and turbulent nucleosynthesis prior to a supernova explosion

Directory of Open Access Journals (Sweden)

W. D. Arnett

2014-03-01

Full Text Available Three-dimensional (3D, time dependent numerical simulations of flow of matter in stars, now have sufficient resolution to be fully turbulent. The late stages of the evolution of massive stars, leading up to core collapse to a neutron star (or black hole, and often to supernova explosion and nucleosynthesis, are strongly convective because of vigorous neutrino cooling and nuclear heating. Unlike models based on current stellar evolutionary practice, these simulations show a chaotic dynamics characteristic of highly turbulent flow. Theoretical analysis of this flow, both in the Reynolds-averaged Navier-Stokes (RANS framework and by simple dynamic models, show an encouraging consistency with the numerical results. It may now be possible to develop physically realistic and robust procedures for convection and mixing which (unlike 3D numerical simulation may be applied throughout the long life times of stars. In addition, a new picture of the presupernova stages is emerging which is more dynamic and interesting (i.e., predictive of new and newly observed phenomena than our previous one.

The exact parity symmetric model and big bang nucleosynthesis

Energy Technology Data Exchange (ETDEWEB)

Foot, R.; Volkas, R.R.

1996-12-01

The assumption of exact, unbroken parity symmetry leads directly to a simple predictive resolution of the atmospheric and solar neutrino puzzles. This is because the existence of this symmetry implies the existence of a set of mirror neutrinos which must mix maximally with the known neutrinos if neutrinos have mass. the maximal mixing of the electron neutrino with the mirror electron neutrino with 3 x 10{sup -10} eV{sup 2} {<=} |{delta}m{sup 2}| {<=} 10{sup -3} eV{sup 2} leads to a predicted reduction of the solar neutrino flux by-a factor of 2, which is in quite good agreement with the experiments. The maximal mixing of the muon neutrino with the mirror muon neutrino with |{delta}m{sup 2}| {approx} 10{sup -2} eV{sup 2} also solves the atmospheric neutrino puzzle. We show that there is a significant range of parameters where these solutions are not in conflict with standard Big Bang Nucleosynthesis when the creation of lepton asymmetry due to neutrino oscillations is taken into account. (authors).

Primordial Black Holes and r-Process Nucleosynthesis.

Science.gov (United States)

Fuller, George M; Kusenko, Alexander; Takhistov, Volodymyr

2017-08-11

We show that some or all of the inventory of r-process nucleosynthesis can be produced in interactions of primordial black holes (PBHs) with neutron stars (NSs) if PBHs with masses 10^{-14}  M_{⊙}

Is the Universe expanding? Fritz Zwicky and the early tired-light hypothesis

Science.gov (United States)

Kragh, Helge

2017-04-01

The recognition that the Universe is in a state of expansion is a milestone in modern astronomy and cosmology. The discovery dates from the early 1930s but was not unanimously accepted by either astronomers or physicists. The relativistic theory of the expanding Universe rested empirically on the redshift-distance law established by Edwin Hubble in 1929. However, although the theory offered a natural explanation of the observed galactic redshifts, these could be explained also on the assumption of a Static Universe. This was what Fritz Zwicky did when he introduced the idea of "tired light" in the fall of 1929. Hypotheses of a similar kind were proposed by several other scientists but their impact on mainstream astronomy and cosmology was limited. The paper offers a survey of tired-light hypotheses in the 1930s and briefly alludes to the later development.

Big Bang Nucleosynthesis and Cosmological Constraints on Neutrino Oscillation Parameters

CERN Document Server

Kirilova, Daniela P; Kirilova, Daniela; Chizhov, Mihail

2001-01-01

We present a review of cosmological nucleosynthesis (CN) with neutrino oscillations, discussing the different effects of oscillations on CN, namely: increase of the effective degrees of freedom during CN, spectrum distortion of the oscillating neutrinos, neutrino number density depletion, and growth of neutrino-antineutrino asymmetry due to active-sterile oscillations. We discuss the importance of these effects for the primordial yield of helium-4. Primordially produced He-4 value is obtained in a selfconsistent study of the nucleons and the oscillating neutrinos. The effects of spectrum distortion, depletion and neutrino-antineutrino asymmetry growth on helium-4 production are explicitly calculated. An update of the cosmological constraints on active-sterile neutrino oscillations parameters is presented, giving the values: delta m^2 sin^8 (2 theta) 0, and |delta m^2| < 8.2 x 10^{-10} eV^2 at large mixing angles for delta m^2 < 0. According to these constraints, besides the active-sterile LMA solution,...

Massive stars with mass loss: Evolution, nucleosynthesis, and astrophysical implications

International Nuclear Information System (INIS)

Prantzos, N.

1986-06-01

Evolution and nucleosynthesis of mass loss WR stars is studied, particularly evolution of stars with initial mass between 50 and 100 solar masses, during combustion of H and He. A semi-empirical mass loss formalism, the Roxburgh criterion for convection, and nuclear data are used. Composition of the stellar surface and ejecta (and ejecta contribution to cosmic ray composition) are derived. The contribution of these stars to s elements in our solar system is shown. Their production of 26 Al is compared to the quantity in the galaxy. Gamma ray emission at 1.8 MeV from the decay of this radionuclide is estimated in galactic longitude. The stars evolve as 0 and 0f stars during H combustion and spend 20% of their He combustion period as WN stars and 80% as WC-W0. Evolution always occurs in the blue part of the HR diagram, and satisfies observational constraints on its upper part [fr

Revisiting big-bang nucleosynthesis constraints on long-lived decaying particles

Science.gov (United States)

Kawasaki, Masahiro; Kohri, Kazunori; Moroi, Takeo; Takaesu, Yoshitaro

2018-01-01

We study the effects of long-lived massive particles, which decayed during the big-bang nucleosynthesis (BBN) epoch, on the primordial abundance of light elements. Compared to previous studies, (i) the reaction rates of standard BBN reactions are updated, (ii) the most recent observational data on the light element abundance and cosmological parameters are used, (iii) the effects of the interconversion of energetic nucleons at the time of inelastic scattering with background nuclei are considered, and (iv) the effects of the hadronic shower induced by energetic high-energy antinucleons are included. We compare the theoretical predictions on the primordial abundance of light elements with the latest observational constraints, and we derive upper bounds on the relic abundance of the decaying particle as a function of its lifetime. We also apply our analysis to an unstable gravitino, the superpartner of a graviton in supersymmetric theories, and obtain constraints on the reheating temperature after inflation.

Social Strategies during University Studies Predict Early Career Work Burnout and Engagement: 18-Year Longitudinal Study

Science.gov (United States)

Salmela-Aro, Katariina; Tolvanen, Asko; Nurmi, Jari-Erik

2011-01-01

This longitudinal study spanning 18 years examined the role of social strategies in early career adaptation. The aim was to find out whether individuals' social strategies measured during their university studies had an impact on work burnout and work engagement measured 10-18 years later. A sample of 292 university students completed the SAQ…

r-Process nucleosynthesis from three-dimensional jet-driven core-collapse supernovae with magnetic misalignments

Science.gov (United States)

Halevi, Goni; Mösta, Philipp

2018-06-01

We investigate r-process nucleosynthesis in three-dimensional general relativistic magnetohydrodynamic simulations of jet-driven supernovae resulting from rapidly rotating, strongly magnetized core-collapse. We explore the effect of misaligning the pre-collapse magnetic field with respect to the rotation axis by performing four simulations: one aligned model and models with 15°, 30°, and 45° misalignments. The simulations we present employ a microphysical finite-temperature equation of state and a leakage scheme that captures the overall energetics and lepton number exchange due to post-bounce neutrino emission and absorption. We track the thermodynamic properties of the ejected material with Lagrangian tracer particles and analyse its composition with the nuclear reaction network SKYNET. By using different neutrino luminosities in post-processing the tracer data with SKYNET, we constrain the impact of uncertainties in neutrino luminosities. We find that, for the aligned model considered here, the use of an approximate leakage scheme results in neutrino luminosity uncertainties corresponding to a factor of 100-1000 uncertainty in the abundance of third peak r-process elements. Our results show that for misalignments of 30° or less, r-process elements are robustly produced as long as neutrino luminosities are reasonably low (≲ 5 × 1052 erg s-1). For a more extreme misalignment of 45°, we find the production of r-process elements beyond the second peak significantly reduced. We conclude that robust r-process nucleosynthesis in magnetorotational supernovae requires a progenitor stellar core with a large poloidal magnetic field component that is at least moderately (within ˜30°) aligned with the rotation axis.

Big bang nucleosynthesis: The standard model and alternatives

International Nuclear Information System (INIS)

Schramm, D.N.

1991-01-01

Big bang nucleosynthesis provides (with the microwave background radiation) one of the two quantitative experimental tests of the big bang cosmological model. This paper reviews the standard homogeneous-isotropic calculation and shows how it fits the light element abundances ranging from 4 He at 24% by mass through 2 H and 3 He at parts in 10 5 down to 7 Li at parts in 10 10 . Furthermore, the recent LEP (and SLC) results on the number of neutrinos are discussed as a positive laboratory test of the standard scenario. Discussion is presented on the improved observational data as well as the improved neutron lifetime data. Alternate scenarios of decaying matter or of quark-hadron induced inhomogeneities are discussed. It is shown that when these scenarios are made to fit the observed abundances accurately, the resulting conclusions on the baryonic density relative to the critical density, Ω b , remain approximately the same as in the standard homogeneous case, thus, adding to the robustness of the conclusion that Ω b ≅0.06. This latter point is the driving force behind the need for non-baryonic dark matter (assuming Ω total =1) and the need for dark baryonic matter, since Ω visible b . (orig.)

Magnetic moment calculation for p+d→ 3 He+γ process in Big=bang nucleosynthesis with effective field theory

International Nuclear Information System (INIS)

Bayegan, S.; Sadeghi, H.

2004-01-01

In big-bang nucleosynthesis, processes relevant ti increasing of nucleon density are more important. One of the theories that its solutions more accurately explain the experimental works is Effective Field Theory in this paper. Magnetic moment (χM1) for radiative capture of protons by deuterons p + d → 3 He+γ process is calculated using Effective Field Theory. The calculation includes coulomb interaction up to next-to -next-leading order (N 2 LO)

Big-bang nucleosynthesis through bound-state effects with a long-lived slepton in the NMSSM

Science.gov (United States)

Kohri, Kazunori; Koike, Masafumi; Konishi, Yasufumi; Ohta, Shingo; Sato, Joe; Shimomura, Takashi; Sugai, Kenichi; Yamanaka, Masato

2014-08-01

We show that the Li problems can be solved in the next-to-minimal supersymmetric standard model where the slepton as the next-to-lightest supersymmetric (SUSY) particle is very long lived. Such a long-lived slepton induces exotic nuclear reactions in big-bang nucleosynthesis, and destroys and produces the Li7 and Li6 nuclei via bound state formation. We study cases where the lightest SUSY particle is singlino-like neutralino and bino-like neutralino to present allowed regions in the parameter space, which is consistent with the observations on the dark matter and the Higgs mass.

(n,γ) (γ,n) unstability in the r process of nucleosynthesis

International Nuclear Information System (INIS)

Duarte, S.J.B.

1977-01-01

The equilibrium approximation for capture and neutron photoemission reactions within r process of nucleosynthesis is analysed. This analysis is considered for whole range of neutron density and temperature which enable the ocurrence of the process. In this way it is necessary to know capture and photo-emission rates for approximately 2000 nuclei. The detailed balance is used in rate relation of above-mencioned reactions, and its application, under temperature, and its application, under temperature conditions and neutron density is discussed. The others nuclear parameters used in face of the nuclei involved in r process are far away of the β stability line. The temperature conditions and neutron density are presented from the point where the equilirbium approximation is not applicable. The procedure to be used in the application of the obtained results in dynamical models of r process is also presented. (M.C.K.) [pt

Limits on cosmological variation of strong interaction and quark masses from big bang nucleosynthesis, cosmic, laboratory and Oklo data

International Nuclear Information System (INIS)

Flambaum, V.V.; Shuryak, E.V.

2002-01-01

Recent data on the cosmological variation of the electromagnetic fine structure constant from distant quasar (QSO) absorption spectra have inspired a more general discussion of the possible variation of other constants. We discuss the variation of strong scale and quark masses. We derive limits on their relative change from (i) primordial big bang nucleosynthesis, (ii) the Oklo natural nuclear reactor, (iii) quasar absorption spectra, and (iv) laboratory measurements of hyperfine intervals

AGN feedback through UFO and galaxy-wide winds in the early Universe

Science.gov (United States)

Feruglio, C.; Piconcelli, E.; Bischetti, M.; Zappacosta, L.; Fiore, F.

2017-10-01

AGN feedback through massive molecular winds is today routinely observed in local AGN host galaxies, but not as such in the early universe. I will present the first evidence for a massive, AGN-driven molecular wind in the z 4 QSO APM08279, which also hosts the most well studied and persistent nuclear semi-raltivistic wind (UFO). This observation directly probes the expansion mechanism of a nuclear wind into the ISM on galaxy wide scales, that so far was constrained by a couple of other objects only (Feruglio et al. 2015, Tombesi et al. 2015). This result also opens the path toward the exploration of molecular AGN-driven winds at early epochs, close after the end of the Epoch of Reionisation (EoR).

The Role of Early Maladaptive Schemas in Prediction of Dysfunctional Attitudes toward Drug Abuse among Students of university

Directory of Open Access Journals (Sweden)

NedaNaeemi

2016-07-01

Full Text Available Drug addiction as the most serious social issue of the world has different sociological, psychological, legal, and political aspects. In this regard, the purpose of this study is to determine the role of early maladaptive schemas in prediction of dysfunctional attitudes toward drug abuse among students of Islamic Azad Universities in Tehran Province, Iran. Statistical population of this study includes all students of Islamic Azad Universities in Tehran Province during 2013 and sample size is equal to 300 members that are randomly chosen. First, the name of university branches in Tehran Province were determined then three branches were randomly chosen out of them and then 300 members were chosen from those branches using random sampling method. All sample members filled out Young Schema Questionnaire Short Form and Dysfunctional Attitude Scale (DAS toward drug. Data were analyzed through regression correlation method and SPSS22 software. The obtained findings indicated a significant relation (P<0/05 between early maladaptive schemas and dysfunctional attitude toward drug abuse among students. Early maladaptive schemas can predict dysfunctional attitudes toward drug among students.

Ground based THz Spectroscopy of Obscured Starbursts in the Early Universe enabled by the 2nd generation Redshift (z) & Early Universe Spectrometer (ZEUS-2)

Science.gov (United States)

Vishwas, Amit; Stacey, Gordon; Nikola, Thomas; Ferkinhoff, Carl; Parshley, Stephen; Schoenwald, Justin; Lamarche, Cody James; Higdon, James; Higdon, Sarah; Brisbin, Drew; Güesten, Rolf; Weiss, Axel; Menten, Karl; Irwin, Kent; Cho, Hsiao-Mei; Niemack, Michael; Hilton, Gene; Hubmayr, Johannes; Amiri, Mandana; Halpern, Mark; Wiebe, Donald; Hasselfield, Matthew; Ade, Peter; Tucker, Carole

2018-01-01

Galaxies were surprisingly dusty in the early Universe, with more than half of the light emitted from stars being absorbed by dust within the system and re-radiated into far infrared (FIR, ~50-150μm) wavelengths. Dusty star forming galaxies (DSFGs) dominate the co-moving star formation rate density of the Universe that peaks around redshift, z~2, making it compelling to study them in rest frame FIR bands. From galaxies at z > 1, the FIR line emission from abundant ions like [O III], [C II] and [N II], are redshifted into the short sub-mm telluric windows. My thesis work is based on building and deploying the 2nd Generation Redshift (z) and Early Universe Spectrometer (ZEUS-2), a long-slit, echelle grating spectrometer optimized to study broad (Δv = 300km/s) spectral lines from galaxies in the 200-650µm telluric windows using TES bolometers. These far-IR lines being extinction free and major coolants of the gas heated by (young) massive stars, are powerful probes of the physical conditions of the gas and the stellar radiation field. I present results from our survey of the [O III] 88µm line in galaxies at redshift, z ~ 2.8 to 4.6, with ZEUS-2 at the Atacama Pathfinder Experiment (APEX) Telescope. To interpret our observations along with ancillary data from optical to radio facilities, we apply photoionization models for HII regions and Photo Dissociation Region (PDR) models and confirm that the galaxies host substantial ongoing obscured star formation. The presence of doubly ionized oxygen suggests hard radiation fields and hence, elevated ionization parameters that can only be accounted for by a large population of massive stars formed during the ongoing starburst, that contribute a large fraction of the infrared luminosity. This study highlights the use of FIR line emission to trace the assembly of current day massive galaxies, conditions of star formation and details of their stellar populations. The construction and operation of ZEUS-2 were funded by NSF ATI

S-factor measurement of the 2H(α,γ)6Li reaction at energies relevant for Big-Bang nucleosynthesis

International Nuclear Information System (INIS)

Anders, Michael

2013-01-01

For about 20 years now, observations of 6 Li in several old metal-poor stars inside the halo of our galaxy have been reported, which are largely independent of the stars' metallicity, and which point to a possible primordial origin. The observations exceed the predictions of the Standard Big-Bang Nucleosynthesis model by a factor of 500. In the relevant energy range, no directly measured S-factors were available yet for the main production reaction 2 H(α,γ) 6 Li, while different theoretical estimations have an uncertainty of up to two orders of magnitude. The very small cross section in the picobarn range has been measured with a deuterium gas target at the LUNA accelerator (Laboratory for Underground Nuclear Astrophysics), located deep underground inside Laboratori Nazionali del Gran Sasso in Italy. A beam-induced, neutron-caused background in the γ-detector occurred which had to be analyzed carefully and subtracted in an appropriate way, to finally infer the weak signal of the reaction. For this purpose, a method to parameterize the Compton background has been developed. The results are a contribution to the discussion about the accuracy of the recent 6 Li observations, and to the question if it is necessary to include new physics into the Standard Big-Bang Nucleosynthesis model.

Constraining f(T) teleparallel gravity by big bang nucleosynthesis. f(T) cosmology and BBN

Energy Technology Data Exchange (ETDEWEB)

Capozziello, S. [Universita di Napoli ' ' Federico II' ' , Complesso Universitario di Monte Sant' Angelo, Dipartimento di Fisica ' ' E. Pancini' ' , Napoli (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Napoli (Italy); Gran Sasso Science Institute, L' Aquila (Italy); Lambiase, G. [University of Salerno, Dipartimento di Fisica E.R. Cainaiello, Fisciano (Italy); INFN, Gruppo Collegato di Salerno, Sezione di Napoli, Fisciano (Italy); Saridakis, E.N. [National Technical University of Athens, Department of Physics, Athens (Greece); Baylor University, CASPER, Physics Department, Waco, TX (United States)

2017-09-15

We use Big Bang Nucleosynthesis (BBN) observational data on the primordial abundance of light elements to constrain f(T) gravity. The three most studied viable f(T) models, namely the power law, the exponential and the square-root exponential are considered, and the BBN bounds are adopted in order to extract constraints on their free parameters. For the power-law model, we find that the constraints are in agreement with those obtained using late-time cosmological data. For the exponential and the square-root exponential models, we show that for reliable regions of parameters space they always satisfy the BBN bounds. We conclude that viable f(T) models can successfully satisfy the BBN constraints. (orig.)

Constraining f(T) teleparallel gravity by big bang nucleosynthesis: f(T) cosmology and BBN.

Science.gov (United States)

Capozziello, S; Lambiase, G; Saridakis, E N

2017-01-01

We use Big Bang Nucleosynthesis (BBN) observational data on the primordial abundance of light elements to constrain f ( T ) gravity. The three most studied viable f ( T ) models, namely the power law, the exponential and the square-root exponential are considered, and the BBN bounds are adopted in order to extract constraints on their free parameters. For the power-law model, we find that the constraints are in agreement with those obtained using late-time cosmological data. For the exponential and the square-root exponential models, we show that for reliable regions of parameters space they always satisfy the BBN bounds. We conclude that viable f ( T ) models can successfully satisfy the BBN constraints.

Constraining f( T) teleparallel gravity by big bang nucleosynthesis. f(T) cosmology and BBN

Science.gov (United States)

Capozziello, S.; Lambiase, G.; Saridakis, E. N.

2017-09-01

We use Big Bang Nucleosynthesis (BBN) observational data on the primordial abundance of light elements to constrain f( T) gravity. The three most studied viable f( T) models, namely the power law, the exponential and the square-root exponential are considered, and the BBN bounds are adopted in order to extract constraints on their free parameters. For the power-law model, we find that the constraints are in agreement with those obtained using late-time cosmological data. For the exponential and the square-root exponential models, we show that for reliable regions of parameters space they always satisfy the BBN bounds. We conclude that viable f( T) models can successfully satisfy the BBN constraints.

Constraining f(T) teleparallel gravity by big bang nucleosynthesis. f(T) cosmology and BBN

International Nuclear Information System (INIS)

Capozziello, S.; Lambiase, G.; Saridakis, E.N.

2017-01-01

We use Big Bang Nucleosynthesis (BBN) observational data on the primordial abundance of light elements to constrain f(T) gravity. The three most studied viable f(T) models, namely the power law, the exponential and the square-root exponential are considered, and the BBN bounds are adopted in order to extract constraints on their free parameters. For the power-law model, we find that the constraints are in agreement with those obtained using late-time cosmological data. For the exponential and the square-root exponential models, we show that for reliable regions of parameters space they always satisfy the BBN bounds. We conclude that viable f(T) models can successfully satisfy the BBN constraints. (orig.)

Why the early Universe preferred the non-supersymmetric vacuum: part II

International Nuclear Information System (INIS)

Abel, Steven A.; Jaeckel, Joerg; Khoze, Valentin V.

2007-01-01

It was recently shown that in the context of the ISS models with a metastable supersymmetry breaking vacuum, thermal effects generically drive the Universe to the metastable vacuum even if it began after inflation in the supersymmetry-preserving one. We continue this programme and specifically take into account two new effects. First is the effect of the mass-gap of the gauge degrees of freedom in the confining supersymmetry preserving vacua, and second, is the effect of the back reaction of the MSSM sector on the SUSY breaking ISS sector. It is shown that, even though the mass-gap is parametrically smaller than the (φ), (φ-tilde) vevs, it drastically reduces the temperature required for the Universe to be driven to the metastable vacuum: essentially any temperature larger than the supersymmetry breaking scale μ is sufficient. On the other hand we also find that any reasonable transmission of SUSY breaking to the MSSM sector has no effect on the vacuum transitions to, and the stability of the SUSY breaking vacuum. We conclude that for these models the early Universe does end up in the SUSY breaking vacuum

Radiative neutron capture on a proton at big-bang nucleosynthesis energies

International Nuclear Information System (INIS)

Ando, S.; Cyburt, R. H.; Hong, S. W.; Hyun, C. H.

2006-01-01

The total cross section for radiative neutron capture on a proton, np→dγ, is evaluated at big-bang nucleosynthesis (BBN) energies. The electromagnetic transition amplitudes are calculated up to next-to-leading-order within the framework of pionless effective field theory with dibaryon fields. We also calculate the dγ→np cross section and the photon analyzing power for the dγ(vector sign)→np process from the amplitudes. The values of low-energy constants that appear in the amplitudes are estimated by a Markov Chain Monte Carlo analysis using the relevant low-energy experimental data. Our result agrees well with those of other theoretical calculations except for the np→dγ cross section at some energies estimated by an R-matrix analysis. We also study the uncertainties in our estimation of the np→dγ cross section at relevant BBN energies and find that the estimated cross section is reliable to within ∼1% error

AMS. A powerful tool for probing nucleosynthesis via long-lived radionuclides

International Nuclear Information System (INIS)

Wallner, A.; Golser, R.; Kutschera, W.; Priller, A.; Steier, P.; Kaeppeler, F.

2005-01-01

The potential of accelerator mass spectrometry (AMS) will be demonstrated on typical radionuclides of interest with half-lives between some years and up to hundred million years. The Vienna Environmental Research Accelerator (VERA) represents a state-of-the-art AMS facility which provides the ability for quantifying nuclides over the whole mass range. At VERA, AMS is used for quantifying long-lived radionuclides within a wide range of applications - from archaeology to astrophysics. Lack of information on cross section data exists for a list of nuclides pointed out by nuclear data requests. The potential of AMS as a powerful tool for probing nucleosynthesis will be demonstrated by means of some prime examples. Recent developments in the technique of AMS will be highlighted and some applications of AMS in astrophysics will be discussed. In addition, an overview on detection limits, measurement precision as well as the recent measurement program at VERA for quantifying such long-lived radionuclides will be presented. (author)

Astrophysical S-factor of the 32He(α,γ) 733 7Be reaction in the Big-Bang nucleosynthesis

Science.gov (United States)

Ghamary, Motahareh; Sadeghi, Hossein; Mohammadi, Saeed

2018-05-01

In the present work, we have studied the properties of the 23He(α , γ) 47Be reaction. The direct radiative capture nuclear reactions in the Big-Bang nucleosynthesis mainly, are done in the external areas of inter-nuclear interaction range and play an essential role in nuclear astrophysics. Among of these reactions, the 23He(α , γ) 47Be reaction with Q = 1.586 MeV is the main part of the Big-Bang nucleosynthesis chain reactions. This reaction can be used to understand the physical and chemical properties of the sun as well as can be justified the lake of the observed solar neutrino in the detector of the Earth. Since product neutrino fluxes are predicated in the center of the sun by the decay of 7Be and 8B, and almost are proportional to the astrophysical S-factor for the 23He(α , γ) 47Be reaction, S34. The 23He(α , γ) 47Be reaction is considered the key to solve the solar neutrino puzzle. Finally, we have astrophysical S-factor obtained for the ground S1,3/2-, first excited S1,1/2-and total S34 states by modern nucleon-nucleon two-body local potential models. We have also compared the obtained S-factor with experimental data and other theoretical works.

One-loop quantum gravity repulsion in the early Universe.

Science.gov (United States)

Broda, Bogusław

2011-03-11

Perturbative quantum gravity formalism is applied to compute the lowest order corrections to the classical spatially flat cosmological Friedmann-Lemaître-Robertson-Walker solution (for the radiation). The presented approach is analogous to the approach applied to compute quantum corrections to the Coulomb potential in electrodynamics, or rather to the approach applied to compute quantum corrections to the Schwarzschild solution in gravity. In the framework of the standard perturbative quantum gravity, it is shown that the corrections to the classical deceleration, coming from the one-loop graviton vacuum polarization (self-energy), have (UV cutoff free) opposite to the classical repulsive properties which are not negligible in the very early Universe. The repulsive "quantum forces" resemble those known from loop quantum cosmology.

Mutated hilltop inflation: a natural choice for early universe

International Nuclear Information System (INIS)

Pal, Barun Kumar; Pal, Supratik; Basu, B.

2010-01-01

We propose a model of inflation with a suitable potential for a single scalar field which falls in the wide class of hilltop inflation. We derive the analytical expressions for most of the physical quantities related to inflation and show that all of them represent the true behavior as required from a model of inflation. We further subject the results to observational verification by formulating the theory of perturbations based on our model followed by an estimation for the values of those observable parameters. Our model is found to be in excellent agreement with observational data. Thus, the features related to the model leads us to infer that this type of hilltop inflation may be a natural choice for explaining the early universe

Production of light elements by cascades from energetic antiprotons in the early Universe and problem of nuclear cosmoarcheology

International Nuclear Information System (INIS)

Levitan, Yu.L.; Sobol', I.M.; Khlopov, M.Yu.; Chechetkin, V.M.

1988-01-01

The mathematical model of the process of light-element (D and 3 He) production due to disintegration of 4 He nuclei, induced by nonequilibrium processes of production of energetic antiprotons in the early Universe is suggested. Numerical calculations show that formation of the nucleon cascade induced by antiproton slowing down increases the D and 3 He yield due to the growth of probability of disintegration of several 4 He nuclei by a single antiproton and due to disintegration of such nuclei by cascade protons. Restraints on the concentration of possible sources of energetic antiprotons in the early Universe are strengthened respectively

Big bang nucleosynthesis: The standard model and alternatives

Science.gov (United States)

Schramm, David N.

1991-01-01

Big bang nucleosynthesis provides (with the microwave background radiation) one of the two quantitative experimental tests of the big bang cosmological model. This paper reviews the standard homogeneous-isotropic calculation and shows how it fits the light element abundances ranging from He-4 at 24% by mass through H-2 and He-3 at parts in 10(exp 5) down to Li-7 at parts in 10(exp 10). Furthermore, the recent large electron positron (LEP) (and the stanford linear collider (SLC)) results on the number of neutrinos are discussed as a positive laboratory test of the standard scenario. Discussion is presented on the improved observational data as well as the improved neutron lifetime data. Alternate scenarios of decaying matter or of quark-hadron induced inhomogeneities are discussed. It is shown that when these scenarios are made to fit the observed abundances accurately, the resulting conlusions on the baryonic density relative to the critical density, omega(sub b) remain approximately the same as in the standard homogeneous case, thus, adding to the robustness of the conclusion that omega(sub b) approximately equals 0.06. This latter point is the driving force behind the need for non-baryonic dark matter (assuming omega(sub total) = 1) and the need for dark baryonic matter, since omega(sub visible) is less than omega(sub b).

Learning and Developing as a University Teacher: Narratives of Early Career Academics in Estonia

Science.gov (United States)

Remmik, Marvi; Karm, Mari; Lepp, Liina

2013-01-01

In recent years the higher education context in Estonia, as in most European countries, has changed a lot. All changes have an impact on university teachers' practice and their work organisation, and are presenting new challenges. The current research aims at developing an understanding of Estonian early career academics' professional identity by…

Constraining the cosmic radiation density due to lepton number with Big Bang Nucleosynthesis

International Nuclear Information System (INIS)

Mangano, Gianpiero; Miele, Gennaro; Pisanti, Ofelia; Sarikas, Srdjan; Pastor, Sergio

2011-01-01

The cosmic energy density in the form of radiation before and during Big Bang Nucleosynthesis (BBN) is typically parameterized in terms of the effective number of neutrinos N eff . This quantity, in case of no extra degrees of freedom, depends upon the chemical potential and the temperature characterizing the three active neutrino distributions, as well as by their possible non-thermal features. In the present analysis we determine the upper bounds that BBN places on N eff from primordial neutrino-antineutrino asymmetries, with a careful treatment of the dynamics of neutrino oscillations. We consider quite a wide range for the total lepton number in the neutrino sector, η ν = η ν e +η ν μ +η ν τ and the initial electron neutrino asymmetry η ν e in , solving the corresponding kinetic equations which rule the dynamics of neutrino (antineutrino) distributions in phase space due to collisions, pair processes and flavor oscillations. New bounds on both the total lepton number in the neutrino sector and the ν e −ν-bar e asymmetry at the onset of BBN are obtained fully exploiting the time evolution of neutrino distributions, as well as the most recent determinations of primordial 2 H/H density ratio and 4 He mass fraction. Note that taking the baryon fraction as measured by WMAP, the 2 H/H abundance plays a relevant role in constraining the allowed regions in the η ν −η ν e in plane. These bounds fix the maximum contribution of neutrinos with primordial asymmetries to N eff as a function of the mixing parameter θ 13 , and point out the upper bound N eff ∼ eff by the Planck satellite will likely provide insight on the nature of the radiation content of the universe

Constraining the cosmic radiation density due to lepton number with Big Bang Nucleosynthesis

Science.gov (United States)

Mangano, Gianpiero; Miele, Gennaro; Pastor, Sergio; Pisanti, Ofelia; Sarikas, Srdjan

2011-03-01

The cosmic energy density in the form of radiation before and during Big Bang Nucleosynthesis (BBN) is typically parameterized in terms of the effective number of neutrinos Neff. This quantity, in case of no extra degrees of freedom, depends upon the chemical potential and the temperature characterizing the three active neutrino distributions, as well as by their possible non-thermal features. In the present analysis we determine the upper bounds that BBN places on Neff from primordial neutrino-antineutrino asymmetries, with a careful treatment of the dynamics of neutrino oscillations. We consider quite a wide range for the total lepton number in the neutrino sector, ην = ηνe+ηνμ+ηντ and the initial electron neutrino asymmetry ηνein, solving the corresponding kinetic equations which rule the dynamics of neutrino (antineutrino) distributions in phase space due to collisions, pair processes and flavor oscillations. New bounds on both the total lepton number in the neutrino sector and the νe-bar nue asymmetry at the onset of BBN are obtained fully exploiting the time evolution of neutrino distributions, as well as the most recent determinations of primordial 2H/H density ratio and 4He mass fraction. Note that taking the baryon fraction as measured by WMAP, the 2H/H abundance plays a relevant role in constraining the allowed regions in the ην-ηνein plane. These bounds fix the maximum contribution of neutrinos with primordial asymmetries to Neff as a function of the mixing parameter θ13, and point out the upper bound Nefflesssim3.4. Comparing these results with the forthcoming measurement of Neff by the Planck satellite will likely provide insight on the nature of the radiation content of the universe.

The quark-hadron transition in cosmology and astrophysics.

Science.gov (United States)

Olive, K A

1991-03-08

A transition from normal hadronic matter (such as protons and neutrons) to quark-gluon matter is expected at both high temperatures and densities. In physical situations, this transition may occur in heavy ion collisions, the early universe, and in the cores of neutron stars. Astrophysics and cosmology can be greatly affected by such a phase transition. With regard to the early universe, big bang nucleosynthesis, the theory describing the primordial origin of the light elements, can be affected by inhomogeneities produced during the transition. A transition to quark matter in the interior by neutron stars further enhances our uncertainties regarding the equation of state of dense nuclear matter and neutron star properties such as the maximum mass and rotation frequencies.

Chaotic Universe, Friedmannian on the average 2

Energy Technology Data Exchange (ETDEWEB)

Marochnik, L S [AN SSSR, Moscow. Inst. Kosmicheskikh Issledovanij

1980-11-01

The cosmological solutions are found for the equations for correlators, describing a statistically chaotic Universe, Friedmannian on the average in which delta-correlated fluctuations with amplitudes h >> 1 are excited. For the equation of state of matter p = n epsilon, the kind of solutions depends on the position of maximum of the spectrum of the metric disturbances. The expansion of the Universe, in which long-wave potential and vortical motions and gravitational waves (modes diverging at t ..-->.. 0) had been excited, tends asymptotically to the Friedmannian one at t ..-->.. identity and depends critically on n: at n < 0.26, the solution for the scalefactor is situated higher than the Friedmannian one, and lower at n > 0.26. The influence of finite at t ..-->.. 0 long-wave fluctuation modes leads to an averaged quasiisotropic solution. The contribution of quantum fluctuations and of short-wave parts of the spectrum of classical fluctuations to the expansion law is considered. Their influence is equivalent to the contribution from an ultrarelativistic gas with corresponding energy density and pressure. The restrictions are obtained for the degree of chaos (the spectrum characteristics) compatible with the observed helium abundance, which could have been retained by a completely chaotic Universe during its expansion up to the nucleosynthesis epoch.

How to avoid a swift kick in the chameleons

International Nuclear Information System (INIS)

Padilla, Antonio; Stefanyszyn, David; Wilson, Toby; Platts, Emma; Walters, Anthony; Weltman, Amanda

2016-01-01

Recently, it was argued that the conformal coupling of the chameleon to matter fields created an issue for early universe cosmology. As standard model degrees of freedom become non-relativistic in the early universe, the chameleon is attracted towards a ''surfing'' solution, so that it arrives at the potential minimum with too large a velocity. This leads to rapid variations in the chameleon's mass and excitation of high energy modes, casting doubts on the classical treatment at Big Bang Nucleosynthesis. Here we present the DBI chameleon, a consistent high energy modification of the chameleon theory that dynamically renders it weakly coupled to matter during the early universe thereby eliminating the adverse effects of the 'kicks'. This is done without any fine tuning of the coupling between the chameleon and matter fields, and retains its screening ability in the solar system. We demonstrate this explicitly with a combination of analytic and numerical results

How to avoid a swift kick in the chameleons

Energy Technology Data Exchange (ETDEWEB)

Padilla, Antonio; Stefanyszyn, David; Wilson, Toby [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Platts, Emma; Walters, Anthony; Weltman, Amanda, E-mail: antonio.padilla@nottingham.ac.uk, E-mail: pltemm002@myuct.ac.za, E-mail: ppxds1@nottingham.ac.uk, E-mail: tony.walters@uct.ac.za, E-mail: amanda.weltman@uct.ac.za, E-mail: toby.wilson@nottingham.ac.uk [Astrophysics, Cosmology and Gravity Centre, Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, Cape Town (South Africa)

2016-03-01

Recently, it was argued that the conformal coupling of the chameleon to matter fields created an issue for early universe cosmology. As standard model degrees of freedom become non-relativistic in the early universe, the chameleon is attracted towards a ''surfing'' solution, so that it arrives at the potential minimum with too large a velocity. This leads to rapid variations in the chameleon's mass and excitation of high energy modes, casting doubts on the classical treatment at Big Bang Nucleosynthesis. Here we present the DBI chameleon, a consistent high energy modification of the chameleon theory that dynamically renders it weakly coupled to matter during the early universe thereby eliminating the adverse effects of the 'kicks'. This is done without any fine tuning of the coupling between the chameleon and matter fields, and retains its screening ability in the solar system. We demonstrate this explicitly with a combination of analytic and numerical results.

Quark matter in astrophysics and cosmology

International Nuclear Information System (INIS)

Olinto, A.V.

1987-10-01

We dicuss the role of quark matter in astrophysics and cosmology. The implications of the dynamics of the quark-hadron phase transition in the early universe for the element abundances from big bang nucleosynthesis and the composition of the dark matter in the universe are addressed. We discuss the possibility of deciding on an equation of state for high density matter by observing the cooling of a neutron star remnant of SN1987A. Quark matter models for the Centauros events, Cygnus X-3 cosmic ray events, high energy gamma-ray bursts and the solar neutrino problem are described. 25 refs., 3 figs

Role of the cosmological constant in the holographic description of the early universe

International Nuclear Information System (INIS)

Myung, Yun Soo

2004-01-01

We investigate the role of the cosmological constant in the holographic description of a radiation-dominated universe C 2 /R 4 with a positive cosmological constant Λ. In order to understand the nature of cosmological term, we first study the Newtonian cosmology. Here we find two aspects of the cosmological term: entropy (Λ→S Λ ) and energy (Λ→E Λ ). Also we solve the Friedmann equation parametrically to obtain another role. In the presence of the cosmological constant, the solutions are described by the Weierstrass elliptic functions on torus and have modular properties. In this case one may expect to have a two-dimensional Cardy entropy formula but the cosmological constant plays a role of the modular parameter τ(C 2 ,Λ) of torus. Consequently, the entropy concept of the cosmological constant is very suitable for establishing the holographic entropy bounds in the early universe. This contrasts to the role of the cosmological constant as a dark energy in the present universe

Were all white holes in the early Universe converted into black holes?

International Nuclear Information System (INIS)

Dey, T.K.; Banerji, S.

1991-01-01

It has been claimed that in the early Universe any white hole must have been converted to a black hole. But taking the simple case of an expanding homogeneous dust sphere colliding with a homogeneous spherical shell of dust which are mutually noninteracting, we find that the mean motion of the combined system will be expanding or contracting to a distant observer according as the combined radius at the instant of collision is less than or greater than the Schwarzschild radius

The Diverse Origins of Neutron-capture Elements in the Metal-poor Star HD 94028: Possible Detection of Products of I-Process Nucleosynthesis

Science.gov (United States)

Roederer, Ian U.; Karakas, Amanda I.; Pignatari, Marco; Herwig, Falk

2016-04-01

We present a detailed analysis of the composition and nucleosynthetic origins of the heavy elements in the metal-poor ([Fe/H] = -1.62 ± 0.09) star HD 94028. Previous studies revealed that this star is mildly enhanced in elements produced by the slow neutron-capture process (s process; e.g., [Pb/Fe] = +0.79 ± 0.32) and rapid neutron-capture process (r process; e.g., [Eu/Fe] = +0.22 ± 0.12), including unusually large molybdenum ([Mo/Fe] = +0.97 ± 0.16) and ruthenium ([Ru/Fe] = +0.69 ± 0.17) enhancements. However, this star is not enhanced in carbon ([C/Fe] = -0.06 ± 0.19). We analyze an archival near-ultraviolet spectrum of HD 94028, collected using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope, and other archival optical spectra collected from ground-based telescopes. We report abundances or upper limits derived from 64 species of 56 elements. We compare these observations with s-process yields from low-metallicity AGB evolution and nucleosynthesis models. No combination of s- and r-process patterns can adequately reproduce the observed abundances, including the super-solar [As/Ge] ratio (+0.99 ± 0.23) and the enhanced [Mo/Fe] and [Ru/Fe] ratios. We can fit these features when including an additional contribution from the intermediate neutron-capture process (I process), which perhaps operated through the ingestion of H in He-burning convective regions in massive stars, super-AGB stars, or low-mass AGB stars. Currently, only the I process appears capable of consistently producing the super-solar [As/Ge] ratios and ratios among neighboring heavy elements found in HD 94028. Other metal-poor stars also show enhanced [As/Ge] ratios, hinting that operation of the I process may have been common in the early Galaxy. These data are associated with Program 072.B-0585(A), PI. Silva. Some data presented in this paper were obtained from the Barbara A. Mikulski Archive for Space Telescopes (MAST). The Space Telescope Science Institute is

Gravitational lensing limits on the cosmological constant in a flat universe

International Nuclear Information System (INIS)

Turner, E.L.

1990-01-01

Inflationary cosmological theories predict, and some more general aesthetic criteria suggest, that the large-scale spatial curvature of the universe k should be accurately zero (i.e., flat), a condition which is satisfied when the universe's present mean density and the value of the cosmological constant Lambda have certain pairs of values. Available data on the frequency of multiple image-lensing of high-redshift quasars by galaxies suggest that the cosmological constant cannot make a dominant contribution to producing a flat universe. In particular, if the mean density of the universe is as small as the baryon density inferred from standard cosmic nucleosynthesis calculations or as determined from typical dynamical studies of galaxies and galaxy clusters, then a value of Lambda large enough to produce a k = 0 universe would result in a substantially higher frequency of multiple-image lensing of quasars than has been observed so far. Shortcomings of the available lens data and uncertainties concerning galaxy properties allow some possibility of escaping this conclusion, but systematic searches for a gravitational lenses and continuing investigations of galaxy mass distributions should soon provide decisive information. It is also noted that nonzero-curvature cosmological models can account for the observed frequency of galaxy-quasar lens systems and for a variety of other constraints. 61 refs

Inflation of the early cold Universe filled with a nonlinear scalar field and a nonideal relativistic Fermi gas

International Nuclear Information System (INIS)

Pashitskii, E. A.; Pentegov, V. I.

2017-01-01

We consider a possible scenario for the evolution of the early cold Universe born from a fairly large quantum fluctuation in a vacuum with a size a_0 ≫ l_P (where l_P is the Planck length) and filled with both a nonlinear scalar field φ, whose potential energy density U(φ) determines the vacuum energy density λ, and a nonideal Fermi gas with short-range repulsion between particles, whose equation of state is characterized by the ratio of pressure P(n_F) to energy density ε(n_F) dependent on the number density of fermions n_F. As the early Universe expands, the dimensionless quantity ν(n_F) = P(n_F)/ε(n_F) decreases with decreasing n_F from its maximum value ν_m_a_x = 1 for n_F → ∞ to zero for n_F → 0. The interaction of the scalar and gravitational fields, which is characterized by a dimensionless constant ξ, is proportional to the scalar curvature of four-dimensional space R = κ[3P(n_F)–ε(n_F)–4λ] (where κ is Einstein’s gravitational constant), and contains terms both quadratic and linear in φ. As a result, the expanding early Universe reaches the point of first-order phase transition in a finite time interval at critical values of the scalar curvature R = R_c =–μ"2/ξ and radius a_c ≫ a_0. Thereafter, the early closed Universe “rolls down” from the flat inflection point of the potential U(φ) to the zero potential minimum in a finite time. The release of the total potential energy of the scalar field in the entire volume of the expanding Universe as it “rolls down” must be accompanied by the production of a large number of massive particles and antiparticles of various kinds, whose annihilation plays the role of the Big Bang. We also discuss the fundamental nature of Newton’ gravitational constant G_N.

The early universe: facts and fiction (astronomy and astrophysics library)

CERN Document Server

Börner, Gerhard

2013-01-01

This fourth edition of Börner's "The Early Universe" is practically a new book, not just updated version. In particular, it is now organized so as to make it more useful as a textbook. And problem sections are also added. In the centre are the connections between particle physics and cosmology: The standard model, some basic implications of quantum field theory and the questions of structure formation. Special emphasis is given to the observed anisotropies of the cosmic microwave background and the consequences drawn for cosmology and for the structure formation models. Nuclear and particle physicists and astrophysicists, researchers and teachers as well as graduate students will welcome this new edition of a classic text and reference.

Impact of Neutrino Flavor Oscillations on the Neutrino-driven Wind Nucleosynthesis of an Electron-capture Supernova

Science.gov (United States)

Pllumbi, Else; Tamborra, Irene; Wanajo, Shinya; Janka, Hans-Thomas; Hüdepohl, Lorenz

2015-08-01

Neutrino oscillations, especially to light sterile states, can affect nucleosynthesis yields because of their possible feedback effect on the electron fraction (Ye). For the first time, we perform nucleosynthesis calculations for neutrino-driven wind trajectories from the neutrino-cooling phase of an 8.8 {M}⊙ electron-capture supernova (SN), whose hydrodynamic evolution was computed in spherical symmetry with sophisticated neutrino transport and whose Ye evolution was post-processed by including neutrino oscillations between both active and active-sterile flavors. We also take into account the α-effect as well as weak magnetism and recoil corrections in the neutrino absorption and emission processes. We observe effects on the Ye evolution that depend in a subtle way on the relative radial positions of the sterile Mikheyev-Smirnov-Wolfenstein resonances, on collective flavor transformations, and on the formation of α particles. For the adopted SN progenitor, we find that neutrino oscillations, also to a sterile state with eV mass, do not significantly affect the element formation and in particular cannot make the post-explosion wind outflow neutron-rich enough to activate a strong r-process. Our conclusions become even more robust when, in order to mimic equation-of-state-dependent corrections due to nucleon potential effects in the dense-medium neutrino opacities, six cases with reduced Ye in the wind are considered. In these cases, despite the conversion of active neutrinos to sterile neutrinos, Ye increases or is not significantly lowered compared to the values obtained without oscillations and active flavor transformations. This is a consequence of a complicated interplay between sterile-neutrino production, neutrino-neutrino interactions, and α-effect.

Particle physics and cosmology

International Nuclear Information System (INIS)

Kolb, E.W.

1986-10-01

This series of lectures is about the role of particle physics in physical processes that occurred in the very early stages of the bug gang. Of particular interest is the role of particle physics in determining the evolution of the early Universe, and the effect of particle physics on the present structure of the Universe. The use of the big bang as a laboratory for placing limits on new particle physics theories will also be discussed. Section 1 reviews the standard cosmology, including primordial nucleosynthesis. Section 2 reviews the decoupling of weakly interacting particles in the early Universe, and discusses neutrino cosmology and the resulting limits that may be placed on the mass and lifetime of massive neutrinos. Section 3 discusses the evolution of the vacuum through phase transitions in the early Universe and the formation of topological defects in the transitions. Section 4 covers recent work on the generation of the baryon asymmetry by baryon-number violating reactions in Grand Unified Theories, and mentions some recent work on baryon number violation effects at the electroweak transition. Section 5 is devoted to theories of cosmic inflation. Finally, Section 6 is a discussion of the role of extra spatial dimensions in the evolution of the early Universe. 78 refs., 32 figs., 6 tabs

Observing the very early universe

CERN Document Server

Steinhardt, Paul Joseph

1995-01-01

Cosmology is entering an historic epoch in which a dazzling array of new observations will decisively test our theories of the origin and evolution of the Universe. Many of the theoretical proposals have profound implications for our understanding of high-energy physics. This lecture series will review some of the leading ideas, especially the inflationary model of the universe, and explain the astrophysical and cosmological observations anticipated for the next decade that will be critical in determining their validity.

Constraints on neutrino degeneracy from the cosmic microwave background and primordial nucleosynthesis

International Nuclear Information System (INIS)

Orito, M.; Kajino, T.; Mathews, G. J.; Wang, Y.

2002-01-01

We reanalyze the cosmological constraints on the existence of a net universal lepton asymmetry and neutrino degeneracy based upon the latest high resolution CMB sky maps from BOOMERANG, DASI, and MAXIMA-1. We generate likelihood functions by marginalizing over (Ω b h 2 ,ξ ν μ,τ ,ξ ν e ,Ω Λ ,h,n) plus the calibration uncertainties. We consider flat Ω M +Ω Λ =1 cosmological models with two identical degenerate neutrino species, ξ ν μ,τ ≡ vertical bar ξ ν μ vertical bar = vertical bar ξ ν τ vertical bar and a small ξ ν e . We assign weak top-hat priors on the electron-neutrino degeneracy parameter ξ ν e and Ω b h 2 based upon allowed values consistent with the nucleosynthesis constraints as a function of ξ ν μ,τ . The change in the background neutrino temperature with degeneracy is also explicitly included, and Gaussian priors for h=0.72±0.08 and the experimental calibration uncertainties are adopted. The marginalized likelihood functions show a slight (0.5σ) preference for neutrino degeneracy. Optimum values with two equally degenerate μ and τ neutrinos imply ξ ν μ,τ =1.0 -1.0(0.5σ) +0.8(1σ) ,from which we deduce ξ ν e =0.09 -0.09 +0.15 , and Ω b h 2 =0.021 -0.002 +0.06 . The 2σ upper limit becomes ξ ν μ,τ ≤2.1, which implies ξ ν e ≤0.30, and Ω b h 2 ≤0.030. For only a single large-degeneracy species the optimal value is vertical bar ξ ν μ vertical bar or vertical bar ξ ν τ vertical bar =1.4 with a 2σ upper limit of vertical bar ξ ν μ vertical bar or vertical bar ξ ν τ vertical bar ≤2.5.

Primordial Black Holes from Supersymmetry in the Early Universe.

Science.gov (United States)

Cotner, Eric; Kusenko, Alexander

2017-07-21

Supersymmetric extensions of the standard model generically predict that in the early Universe a scalar condensate can form and fragment into Q balls before decaying. If the Q balls dominate the energy density for some period of time, the relatively large fluctuations in their number density can lead to formation of primordial black holes (PBH). Other scalar fields, unrelated to supersymmetry, can play a similar role. For a general charged scalar field, this robust mechanism can generate black holes over the entire mass range allowed by observational constraints, with a sufficient abundance to account for all dark matter in some parameter ranges. In the case of supersymmetry the mass range is limited from above by 10^{23}  g. We also comment on the role that topological defects can play for PBH formation in a similar fashion.

General neutralino NLSP with gravitino dark matter vs. big bang nucleosynthesis

Energy Technology Data Exchange (ETDEWEB)

Hasenkamp, Jasper

2009-08-15

We study the scenario of gravitino dark matter with a general neutralino being the next-to-lightest supersymmetric particle (NLSP). Therefore, we compute analytically all 2- and 3-body decays of the neutralino NLSP to determine the lifetime and the electromagnetic and hadronic branching ratio of the neutralino decaying into the gravitino and Standard Model particles. We constrain the gravitino and neutralino NLSP mass via big bang nucleosynthesis and see how those bounds are relaxed for a Higgsino or a wino NLSP in comparison to the bino neutralino case. At neutralino masses >or similar 1 TeV, a wino NLSP is favoured, since it decays rapidly via a newly found 4-vertex. The Higgsino component becomes important, when resonant annihilation via heavy Higgses can occur. We provide the full analytic results for the decay widths and the complete set of Feynman rules necessary for these computations. This thesis closes any gap in the study of gravitino dark matter scenarios with neutralino NLSP coming from approximations in the calculation of the neutralino decay rates and its hadronic branching ratio. (orig.)

General neutralino NLSP with gravitino dark matter vs. big bang nucleosynthesis

International Nuclear Information System (INIS)

Hasenkamp, Jasper

2009-08-01

We study the scenario of gravitino dark matter with a general neutralino being the next-to-lightest supersymmetric particle (NLSP). Therefore, we compute analytically all 2- and 3-body decays of the neutralino NLSP to determine the lifetime and the electromagnetic and hadronic branching ratio of the neutralino decaying into the gravitino and Standard Model particles. We constrain the gravitino and neutralino NLSP mass via big bang nucleosynthesis and see how those bounds are relaxed for a Higgsino or a wino NLSP in comparison to the bino neutralino case. At neutralino masses >or similar 1 TeV, a wino NLSP is favoured, since it decays rapidly via a newly found 4-vertex. The Higgsino component becomes important, when resonant annihilation via heavy Higgses can occur. We provide the full analytic results for the decay widths and the complete set of Feynman rules necessary for these computations. This thesis closes any gap in the study of gravitino dark matter scenarios with neutralino NLSP coming from approximations in the calculation of the neutralino decay rates and its hadronic branching ratio. (orig.)

Early Gender Gaps among University Graduates

OpenAIRE

Francesconi, Marco; Parey, Matthias

2018-01-01

We use data from six cohorts of university graduates in Germany to assess the extent of gender gaps in college and labor market performance twelve to eighteen months after graduation. Men and women enter college in roughly equal numbers, but more women than men complete their degrees. Women enter college with slightly better high school grades, but women leave university with slightly lower marks. Immediately following university completion, male and female full-timers work very similar numbe...

Near-Ultraviolet Observations of CS 29497-030: New Constraints on Neutron-Capture Nucleosynthesis Processes

Science.gov (United States)

Ivans, Inese I.; Sneden, Christopher; Gallino, Roberto; Cowan, John J.; Preston, George W.

2005-07-01

Employing spectra obtained with the new Keck I HIRES near-UV-sensitive detector, we have performed a comprehensive chemical composition analysis of the binary blue metal-poor star CS 29497-030. Abundances for 29 elements and upper limits for an additional seven have been derived, concentrating on elements largely produced by means of neutron-capture nucleosynthesis. Included in our analysis are the two elements that define the termination point of the slow neutron-capture process, lead and bismuth. We determine an extremely high value of [Pb/Fe]=+3.65+/-0.07 (σ=0.13) from three features, supporting the single-feature result obtained in previous studies. We detect Bi for the first time in a metal-poor star. Our derived Bi/Pb ratio is in accord with those predicted from the most recent FRANEC calculations of the slow neutron-capture process in low-mass asymptotic giant branch (AGB) stars. We find that the neutron-capture elemental abundances of CS 29497-030 are best explained by an AGB model that also includes very significant amounts of pre-enrichment of rapid neutron-capture process material in the protostellar cloud out of which the CS 29497-030 binary system formed. Mass transfer is consistent with the observed [Nb/Zr]~0. Thus, CS 29497-030 is both an r+s and ``extrinsic AGB'' star. Furthermore, we find that the mass of the AGB model can be further constrained by the abundance of the light odd-element Na. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

Supersonic gas streams enhance the formation of massive black holes in the early universe.

Science.gov (United States)

Hirano, Shingo; Hosokawa, Takashi; Yoshida, Naoki; Kuiper, Rolf

2017-09-29

The origin of super-massive black holes in the early universe remains poorly understood. Gravitational collapse of a massive primordial gas cloud is a promising initial process, but theoretical studies have difficulty growing the black hole fast enough. We report numerical simulations of early black hole formation starting from realistic cosmological conditions. Supersonic gas motions left over from the Big Bang prevent early gas cloud formation until rapid gas condensation is triggered in a protogalactic halo. A protostar is formed in the dense, turbulent gas cloud, and it grows by sporadic mass accretion until it acquires 34,000 solar masses. The massive star ends its life with a catastrophic collapse to leave a black hole-a promising seed for the formation of a monstrous black hole. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Spacetime deformation effect on the early universe and the PTOLEMY experiment

Directory of Open Access Journals (Sweden)

Raul Horvat

2017-09-01

Full Text Available Using a fully-fledged formulation of gauge field theory deformed by the spacetime noncommutativity, we study its impact on relic neutrino direct detection, as proposed recently by the PTOLEMY experiment. The noncommutative background tends to influence the propagating neutrinos by providing them with a tree-level vector-like coupling to photons, enabling thus otherwise sterile right-handed (RH neutrinos to be thermally produced in the early universe. Such a new component in the universe's background radiation has been switched today to the almost fully active sea of non-relativistic neutrinos, exerting consequently some impact on the capture on tritium at PTOLEMY. The peculiarities of our nonperturbative approach tend to reflect in the cosmology as well, upon the appearances of the coupling temperature, above which RH neutrinos stay permanently decoupled from thermal environment. This entails the maximal scale of noncommutativity as well, being of order of 10−4MPl, above which there is no impact whatsoever on the capture rates at PTOLEMY. The latter represents an exceptional upper bound on the scale of noncommutativity coming from phenomenology.

Cosmological Constraints on Decoupled Dark Photons and Dark Higgs

Energy Technology Data Exchange (ETDEWEB)

Berger, Joshua [Univ. of Wisconsin, Madison, WI (United States); Jedamzik, Karsten [Univ. Montpellier II (France). Lab. Univers. et Particules de Monpellier; Walker, Devin G.E. [Univ. of Washington, Seattle, WA (United States). Dept. of Physics

2016-05-23

Any neutral boson such as a dark photon or dark Higgs that is part of a non-standard sector of particles can mix with its standard model counterpart. When very weakly mixed with the Standard Model, these particles are produced in the early Universe via the freeze-in mechanism and subsequently decay back to standard model particles. In this work, we place constraints on such mediator decays by considering bounds from Big Bang nucleosynthesis and the cosmic microwave background radiation. We find both nucleosynthesis and CMB can constrain dark photons with a kinetic mixing parameter between log ϵ ~ -10 to -17 for masses between 1 MeV and 100 GeV. Similarly, the dark Higgs mixing angle ϵ with the Standard Model Higgs is constrained between log ϵ ~ -6 to -15. Dramatic improvement on the bounds from CMB spectral distortions can be achieved with proposed experiments such as PIXIE.

Experimental investigation of the reactions 25Mg(α,n)28Si, 26Mg(α,n)29Si, 18O(α,n)21Ne and their impact on stellar nucleosynthesis

International Nuclear Information System (INIS)

Falahat, Sascha

2010-01-01

In the present dissertation, the nuclear reactions 25 Mg(α,n) 28 Si, 26 Mg(α,n) 29 Si, 18 O(α,n) 21 Ne are investigated in the astrophysically interesting energy region from E α =1000 keV to E α =2450 keV. The experiments were performed at the Nuclear Structure Laboratory of the University of Notre Dame (USA) with the Van-de-Graaff accelerator KN. Solid state targets with evaporated magnesium or anodized oxygen were bombarded with α-particles and the released neutrons detected. For the detection of the released neutrons, computational simulations were used to construct a neutron detector based on 3 He counters. Because of the strong occurrence of background reactions, different methods of data analysis were employed. Finally, the impact of the reactions 25 Mg(α,n) 28 Si, 26 Mg(α,n) 29 Si, 18 O(α,n) 21 Ne on stellar nucleosynthesis is investigated by means of network calculations. (orig.)

The first second of the Universe

CERN Document Server

Schwarz, Dominik J

2003-01-01

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 tested directly yet; however, it is constrained by experiments at particle and heavy ion accelerators. Here I attempt to describe the epoch between the electroweak transition and the primordial nucleosynthesis. The most dramatic event in that era is the quark--hadron transition at 10 $\\mu$s. Quarks and gluons condense to form a gas of nucleons and light mesons, the latter decay subsequently. At the end of the first second, neutrinos and neutrons decouple from the radiation fluid. The quark--hadron transition and dissipative processes during the first second prepare the initial conditions for the synthesis of the first nuclei. As for the cold dark matter (CDM), WIMPs (weakly interacting massive particles) -- the most popular candidates for the CDM -- decouple from the presently...

Explosive nucleosynthesis in a neutrino-driven core collapse supernova

International Nuclear Information System (INIS)

Fujimoto, Shin-ichiro; Kotake, Kei; Hashimoto, Masa-aki; Ono, Masaomi; Ohnishi, Naofumi

2010-01-01

We investigate explosive nucleosynthesis in a delayed neutrino-driven, supernova explosion aided by standing accretion shock instability (SASI), based on two-dimensional hydrodynamic simulations of the explosion of a 15 M · star. We take into accounts neutrino heating and cooling as well as change in electron fraction due to weak interactions appropriately, in the two-dimensional simulations. We assume the isotropic emission of neutrinos from the neutrino spheres with given luminosities. and the Fermi-Dirac distribution of given temperatures. We find that the stalled shock revives due to the neutrino heating aided by SASI for cases with L νe ≥3.9x10 52 ergss -1 and the as-pherical shock passes through the outer layers of the star (≥10,000 km), with the explosion energies of ∼10 51 ergs.Next we examine abundances and masses of the supernova ejecta. We find that masses of the ejecta and 56 Ni correlate with the neutrino luminosity, and 56 Ni mass is comparable to that observed in SN 1987A. We also find that abundance pattern of the supernova ejecta is similar to that of the solar system, for cases with high explosion energies of >10 51 ergs. We emphasize that 64 Zn, which is underproduced in the spherical case, is abundantly produced in slightly neutron-rich ejecta.

On Effective Degrees of Freedom in the Early Universe

Directory of Open Access Journals (Sweden)

Lars Husdal

2016-12-01

Full Text Available We explore the effective degrees of freedom in the early Universe, from before the electroweak scale at a few femtoseconds after the Big Bang until the last positrons disappeared a few minutes later. We look at the established concepts of effective degrees of freedom for energy density, pressure, and entropy density, and introduce effective degrees of freedom for number density as well. We discuss what happens with particle species as their temperature cools down from relativistic to semi- and non-relativistic temperatures, and then annihilates completely. This will affect the pressure and the entropy per particle. We also look at the transition from a quark-gluon plasma to a hadron gas. Using a list a known hadrons, we use a “cross-over” temperature of 214 MeV, where the effective degrees of freedom for a quark-gluon plasma equals that of a hadron gas.

Inflation of the early cold Universe filled with a nonlinear scalar field and a nonideal relativistic Fermi gas

Energy Technology Data Exchange (ETDEWEB)

Pashitskii, E. A., E-mail: pashitsk@iop.kiev.ua; Pentegov, V. I., E-mail: pentegov@iop.kiev.ua [National Academy of Sciences of Ukraine, Institute of Physics (Ukraine)

2017-03-15

We consider a possible scenario for the evolution of the early cold Universe born from a fairly large quantum fluctuation in a vacuum with a size a{sub 0} ≫ l{sub P} (where l{sub P} is the Planck length) and filled with both a nonlinear scalar field φ, whose potential energy density U(φ) determines the vacuum energy density λ, and a nonideal Fermi gas with short-range repulsion between particles, whose equation of state is characterized by the ratio of pressure P(n{sub F}) to energy density ε(n{sub F}) dependent on the number density of fermions n{sub F}. As the early Universe expands, the dimensionless quantity ν(n{sub F}) = P(n{sub F})/ε(n{sub F}) decreases with decreasing n{sub F} from its maximum value ν{sub max} = 1 for n{sub F} → ∞ to zero for n{sub F} → 0. The interaction of the scalar and gravitational fields, which is characterized by a dimensionless constant ξ, is proportional to the scalar curvature of four-dimensional space R = κ[3P(n{sub F})–ε(n{sub F})–4λ] (where κ is Einstein’s gravitational constant), and contains terms both quadratic and linear in φ. As a result, the expanding early Universe reaches the point of first-order phase transition in a finite time interval at critical values of the scalar curvature R = R{sub c} =–μ{sup 2}/ξ and radius a{sub c} ≫ a{sub 0}. Thereafter, the early closed Universe “rolls down” from the flat inflection point of the potential U(φ) to the zero potential minimum in a finite time. The release of the total potential energy of the scalar field in the entire volume of the expanding Universe as it “rolls down” must be accompanied by the production of a large number of massive particles and antiparticles of various kinds, whose annihilation plays the role of the Big Bang. We also discuss the fundamental nature of Newton’ gravitational constant G{sub N}.

Analytical treatment of neutrino asymmetry equilibration from flavor oscillations in the early universe

Science.gov (United States)

Wong, Yvonne Y.

2002-07-01

A recent numerical study by A. D. Dolgov, S. H. Hansen, S. Pastor, S. T. Petcov, G. G. Raffelt, and D. V. Semikoz (DHPPRS) [Nucl. Phys. B632, 363 (2002)] found that complete or partial equilibrium between all active neutrino flavors can be achieved before the big bang nucleosynthesis epoch via flavor oscillations, if the oscillation parameters are those inferred from the atmospheric and solar neutrino data, and, in some cases, if θ13 is also sizable. As such, cosmological constraints on the electron neutrino-antineutrino asymmetry are now applicable in all three neutrino sectors. In the present work, we provide an analytical treatment of the scenarios considered in DHPPRS, and demonstrate that their results are stable even for very large initial asymmetries. The equilibration mechanism can be understood in terms of a Mikheyev-Smirnov-Wolfenstein-like effect for a maximally mixed and effectively monochromatic system. We also comment on the DHPPRS's choices of mixing parameters, and their handling of collisional effects, both of which could impinge on the extent of flavor equilibrium.

Introduction to the theory of the early universe hot Big Bang theory

CERN Document Server

Rubakov, Valery A

2018-01-01

This book is written from the viewpoint that a deep connection exists between cosmology and particle physics. It presents the results and ideas on both the homogeneous and isotropic Universe at the hot stage of its evolution and in later stages. The main chapters describe in a systematic and pedagogical way established facts and concepts on the early and the present Universe. The comprehensive treatment, hence, serves as a modern introduction to this rapidly developing field of science. To help in reading the chapters without having to constantly consult other texts, essential materials from General Relativity and the theory of elementary particles are collected in the appendices. Various hypotheses dealing with unsolved problems of cosmology, and often alternative to each other, are discussed at a more advanced level. These concern dark matter, dark energy, matter–antimatter asymmetry, etc. Particle physics and cosmology underwent rapid development between the first and the second editions of this book. I...

Neutrinos in the Early Universe, Kalb-Ramond Torsion and Matter-Antimatter Asymmetry

Directory of Open Access Journals (Sweden)

Mavromatos Nick E.

2014-04-01

Full Text Available The generation of a matter-antimatter asymmetry in the universe may be induced by the propagation of fermions in non-trivial, spherically asymmetric (and hence Lorentz violating gravitational backgrounds. Such backgrounds may characterise the epoch of the early universe. The key point in these models is that the background induces di_erent dispersion relations, hence populations, between fermions and antifermions, and thus CPT Violation (CPTV appears in thermal equilibrium. Species populations may freeze out leading to leptogenesis and baryogenesis. We consider here a string-inspired scenario, in which the CPTV is associated with a cosmological background with torsion provided by the Kalb-Ramond (KR antisymemtric tensor field of the string gravitational multiplet. In a four-dimensional space time this field is dual to a pseudoscalar “axionlike” field. The mixing of the KR field with an ordinary axion field can lead to the generation of a Majorana neutrino mass.

Primordial alchemy: a test of the standard model

International Nuclear Information System (INIS)

Steigman, G.

1987-01-01

Big Bang Nucleosynthesis provides the only probe of the early evolution of the Universe constrained by observational data. The standard, hot, big bang model predicts the synthesis of the light elements (D, 3 He, 4 He, 7 Li) in astrophysically interesting abundances during the first few minutes in the evolution of the Universe. A quantitative comparison of the predicted abundances with those observed astronomically confirms the consistency of the standard model and yields valuable constraints on the parameters of cosmology and elementary particle physics. The current status of the comparison between theory and observation will be reviewed and the opportunities for future advances outlined

Using Inertial Fusion Implosions to Measure the T+^{3}He Fusion Cross Section at Nucleosynthesis-Relevant Energies.

Science.gov (United States)

Zylstra, A B; Herrmann, H W; Johnson, M Gatu; Kim, Y H; Frenje, J A; Hale, G; Li, C K; Rubery, M; Paris, M; Bacher, A; Brune, C R; Forrest, C; Glebov, V Yu; Janezic, R; McNabb, D; Nikroo, A; Pino, J; Sangster, T C; Séguin, F H; Seka, W; Sio, H; Stoeckl, C; Petrasso, R D

2016-07-15

Light nuclei were created during big-bang nucleosynthesis (BBN). Standard BBN theory, using rates inferred from accelerator-beam data, cannot explain high levels of ^{6}Li in low-metallicity stars. Using high-energy-density plasmas we measure the T(^{3}He,γ)^{6}Li reaction rate, a candidate for anomalously high ^{6}Li production; we find that the rate is too low to explain the observations, and different than values used in common BBN models. This is the first data directly relevant to BBN, and also the first use of laboratory plasmas, at comparable conditions to astrophysical systems, to address a problem in nuclear astrophysics.

Inflaton and metric fluctuations in the early universe from a 5D vacuum state

Science.gov (United States)

Membiela, Agustin; Bellini, Mauricio

2006-04-01

In this Letter we complete a previously introduced formalism to study the gauge-invariant metric fluctuations from a noncompact Kaluza Klein theory of gravity, to study the evolution of the early universe. The evolution of both, metric and inflaton field fluctuations are reciprocally related. We obtain that /ρ depends on the coupling of Φ with δφ and the spectral index of its spectrum is 0.9483

Inflaton and metric fluctuations in the early universe from a 5D vacuum state

International Nuclear Information System (INIS)

Membiela, Agustin; Bellini, Mauricio

2006-01-01

In this Letter we complete a previously introduced formalism to study the gauge-invariant metric fluctuations from a noncompact Kaluza-Klein theory of gravity, to study the evolution of the early universe. The evolution of both, metric and inflaton field fluctuations are reciprocally related. We obtain that /ρ b depends on the coupling of Φ with δφ and the spectral index of its spectrum is 0.9483 1 <1

Aspherical nucleosynthesis in a core-collapse supernova with 25 M {sub ☉} standard progenitor

Energy Technology Data Exchange (ETDEWEB)

Popov, M. V. [École Normale Supérieure de Lyon, CRAL (UMR CNRS 5574), Université de Lyon 1, 46 allée d' Italie, F-69007 Lyon (France); Filina, A. A.; Baranov, A. A.; Chardonnet, P. [LAPTh, Université de Savoie, 9, Chemin de Bellevue BP 110, F-74941 Annecy-le-Vieux Cedex (France); Chechetkin, V. M. [Keldysh Institute of Applied Mathematics RAS, Miusskaya sq. 4, 125047 Moscow (Russian Federation)

2014-03-01

The problem of nucleosynthesis was studied within an aspherical supernova model. The explosive burning was computed in a star of 25 M {sub ☉} initial mass on its final stage of evolution. The chemical composition of a presupernova was taken from realistic evolutionary computations. A piecewise parabolic method on a local stencil was applied to simulate the hydrodynamics of the explosion. The gravity was recomputed by a Poisson solver on a fine grid as the explosion developed. A detailed yield of chemical elements was performed as a post-processing step using the tracer particles method. The produced nuclei formed a layer-like structure enclosing large fragments of nickel and iron-group isotopes that were pushed away from the central region by an explosion along the polar direction. The light nuclei were preferentially moving along the equatorial plane forming a torus-like structure.

Inequilibrium cosmological light element nucleosynthesis. Calculations by the Monte Carlo method

International Nuclear Information System (INIS)

Khlopov, M.Yu.; Levitan, Yu.L.; Sedel'nikov, E.V.; Sobol, I.M.

1993-07-01

Formation of light nuclei ( 6 Li, 7 Li, 7 Be) is studied by Monte Carlo simulation of interactions between 4 He nuclei and inequilibrium fluxes of D,Γ, 3 He, 4 He nuclei, that were produced in nuclear cascades induced by decay products of hypothetical metastable objects in early Universe. The dependence of the amount of 6 Li, 7 Li, 7 Be nuclei on parameters of an analytic approximation of the experimental momentum distribution of secondary nuclei in N(N-bar) induced 4 He dissociation is analyzed. (author). 3 refs, 2 tabs

The cosmological lithium problem revisited

International Nuclear Information System (INIS)

Bertulani, C. A.; Mukhamedzhanov, A. M.; Shubhchintak

2016-01-01

After a brief review of the cosmological lithium problem, we report a few recent attempts to find theoretical solutions by our group at Texas A&M University (Commerce & College Station). We will discuss our studies on the theoretical description of electron screening, the possible existence of parallel universes of dark matter, and the use of non-extensive statistics during the Big Bang nucleosynthesis epoch. Last but not least, we discuss possible solutions within nuclear physics realm. The impact of recent measurements of relevant nuclear reaction cross sections for the Big Bang nucleosynthesis based on indirect methods is also assessed. Although our attempts may not able to explain the observed discrepancies between theory and observations, they suggest theoretical developments that can be useful also for stellar nucleosynthesis.

The cosmological lithium problem revisited

Energy Technology Data Exchange (ETDEWEB)

Bertulani, C. A., E-mail: carlos.bertulani@tamuc.edu [Department of Physics and Astronomy, Texas A& M University-Commerce, Commerce, TX 75429 (United States); Department of Physics and Astronomy, Texas A& M University, College Station, TX 75429 (United States); Mukhamedzhanov, A. M., E-mail: akram@comp.tamu.edu [Department of Physics and Astronomy, Texas A& M University, College Station, TX 75429 (United States); Shubhchintak, E-mail: shub.shubhchintak@tamuc.edu [Department of Physics and Astronomy, Texas A& M University-Commerce, Commerce, TX 75429 (United States)

2016-07-07

After a brief review of the cosmological lithium problem, we report a few recent attempts to find theoretical solutions by our group at Texas A&M University (Commerce & College Station). We will discuss our studies on the theoretical description of electron screening, the possible existence of parallel universes of dark matter, and the use of non-extensive statistics during the Big Bang nucleosynthesis epoch. Last but not least, we discuss possible solutions within nuclear physics realm. The impact of recent measurements of relevant nuclear reaction cross sections for the Big Bang nucleosynthesis based on indirect methods is also assessed. Although our attempts may not able to explain the observed discrepancies between theory and observations, they suggest theoretical developments that can be useful also for stellar nucleosynthesis.

Parametric Resonance in the Early Universe - A Fitting Analysis

CERN Document Server

Figueroa, Daniel G.

2017-02-01

Particle production via parametric resonance in the early Universe, is a non-perturbative, non-linear and out-of-equilibrium phenomenon. Although it is a well studied topic, whenever a new scenario exhibits parametric resonance, a full re-analysis is normally required. To avoid this tedious task, many works present often only a simplified linear treatment of the problem. In order to surpass this circumstance in the future, we provide a fitting analysis of parametric resonance through all its relevant stages: initial linear growth, non-linear evolution, and relaxation towards equilibrium. Using lattice simulations in an expanding grid in $3+1$ dimensions, we parametrise the dynamics' outcome scanning over the relevant ingredients: role of the oscillatory field, particle coupling strength, initial conditions, and background expansion rate. We emphasise the inaccuracy of the linear calculation of the decay time of the oscillatory field, and propose a more appropriate definition of this scale based on the subsequ...

Turbulence of Weak Gravitational Waves in the Early Universe.

Science.gov (United States)

Galtier, Sébastien; Nazarenko, Sergey V

2017-12-01

We study the statistical properties of an ensemble of weak gravitational waves interacting nonlinearly in a flat space-time. We show that the resonant three-wave interactions are absent and develop a theory for four-wave interactions in the reduced case of a 2.5+1 diagonal metric tensor. In this limit, where only plus-polarized gravitational waves are present, we derive the interaction Hamiltonian and consider the asymptotic regime of weak gravitational wave turbulence. Both direct and inverse cascades are found for the energy and the wave action, respectively, and the corresponding wave spectra are derived. The inverse cascade is characterized by a finite-time propagation of the metric excitations-a process similar to an explosive nonequilibrium Bose-Einstein condensation, which provides an efficient mechanism to ironing out small-scale inhomogeneities. The direct cascade leads to an accumulation of the radiation energy in the system. These processes might be important for understanding the early Universe where a background of weak nonlinear gravitational waves is expected.

Underground Study of Big Bang Nucleosynthesis in the Precision Era of Cosmology

Directory of Open Access Journals (Sweden)

Gustavino Carlo

2017-01-01

Full Text Available Big Bang Nucleosinthesis (BBN theory provides definite predictions for the abundance of light elements produced in the early universe, as far as the knowledge of the relevant nuclear processes of the BBN chain is accurate. At BBN energies (30 ≲ Ecm ≲ 300 MeV the cross section of many BBN processes is very low because of the Coulomb repulsion between the interacting nuclei. For this reason it is convenient to perform the measurements deep underground. Presently the world’s only facility operating underground is LUNA (Laboratory for Undergound Nuclear astrophysics at LNGS (“Laboratorio Nazionale del Gran Sasso”, Italy. In this presentation the BBN measurements of LUNA are briefly reviewed and discussed. It will be shown that the ongoing study of the D(p, γ3He reaction is of primary importance to derive the baryon density of universe Ωb with high accuracy. Moreover, this study allows to constrain the existence of the so called “dark radiation”, composed by undiscovered relativistic species permeating the universe, such as sterile neutrinos.

Underground Study of Big Bang Nucleosynthesis in the Precision Era of Cosmology

Science.gov (United States)

Gustavino, Carlo

2017-03-01

Big Bang Nucleosinthesis (BBN) theory provides definite predictions for the abundance of light elements produced in the early universe, as far as the knowledge of the relevant nuclear processes of the BBN chain is accurate. At BBN energies (30 ≲ Ecm ≲ 300 MeV) the cross section of many BBN processes is very low because of the Coulomb repulsion between the interacting nuclei. For this reason it is convenient to perform the measurements deep underground. Presently the world's only facility operating underground is LUNA (Laboratory for Undergound Nuclear astrophysics) at LNGS ("Laboratorio Nazionale del Gran Sasso", Italy). In this presentation the BBN measurements of LUNA are briefly reviewed and discussed. It will be shown that the ongoing study of the D(p, γ)3He reaction is of primary importance to derive the baryon density of universe Ωb with high accuracy. Moreover, this study allows to constrain the existence of the so called "dark radiation", composed by undiscovered relativistic species permeating the universe, such as sterile neutrinos.

Pseudoscalar Fields in Torsionful Geometries of the Early Universe, the Baryon Asymmetry and Majorana Neutrino Mass Generation

CERN Document Server

Mavromatos, Nick E.

2015-11-03

We discuss here a specific field-theory model, inspired from string theory, in which the generation of a matter-antimatter asymmetry in the Cosmos is due to the propagation of fermions in a non-trivial, spherically asymmetric (and hence Lorentz violating) gravitational background that may characterise the epochs of the early universe. The background induces different dispersion relations, hence populations, between fermions and antifermions, and thus CPT Violation (CPTV) already in thermal equilibrium. Species populations may freeze out leading to leptogenesis and baryogenesis. More specifically, after reviewing some generic models of background-induced CPTV in early epochs of the Universe, we consider a string-inspired scenario, in which the CPTV is associated with a cosmological background with torsion provided by the Kalb-Ramond (KR) antisymemtric tensor field of the string gravitational multiplet. In a four-dimensional space time this field is dual to a pseudoscalar ``axion-like'' field. The thermalising ...

Constraining the cosmic radiation density due to lepton number with Big Bang Nucleosynthesis

Energy Technology Data Exchange (ETDEWEB)

Mangano, Gianpiero; Miele, Gennaro; Pisanti, Ofelia; Sarikas, Srdjan [Istituto Nazionale di Fisica Nucleare – Sezione di Napoli, Complesso Universitario di Monte S. Angelo, I-80126 Napoli (Italy); Pastor, Sergio, E-mail: mangano@na.infn.it, E-mail: miele@na.infn.it, E-mail: pastor@ific.uv.es, E-mail: pisanti@na.infn.it, E-mail: sarikas@na.infn.it [Instituto de Física Corpuscular (CSIC-Universitat de València), Ed. Institutos de Investigación, Apdo. correos 22085, E-46071 Valencia (Spain)

2011-03-01

The cosmic energy density in the form of radiation before and during Big Bang Nucleosynthesis (BBN) is typically parameterized in terms of the effective number of neutrinos N{sub eff}. This quantity, in case of no extra degrees of freedom, depends upon the chemical potential and the temperature characterizing the three active neutrino distributions, as well as by their possible non-thermal features. In the present analysis we determine the upper bounds that BBN places on N{sub eff} from primordial neutrino-antineutrino asymmetries, with a careful treatment of the dynamics of neutrino oscillations. We consider quite a wide range for the total lepton number in the neutrino sector, η{sub ν} = η{sub ν{sub e}}+η{sub ν{sub μ}}+η{sub ν{sub τ}} and the initial electron neutrino asymmetry η{sub ν{sub e}{sup in}}, solving the corresponding kinetic equations which rule the dynamics of neutrino (antineutrino) distributions in phase space due to collisions, pair processes and flavor oscillations. New bounds on both the total lepton number in the neutrino sector and the ν{sub e}−ν-bar {sub e} asymmetry at the onset of BBN are obtained fully exploiting the time evolution of neutrino distributions, as well as the most recent determinations of primordial {sup 2}H/H density ratio and {sup 4}He mass fraction. Note that taking the baryon fraction as measured by WMAP, the {sup 2}H/H abundance plays a relevant role in constraining the allowed regions in the η{sub ν}−η{sub ν{sub e}{sup in}} plane. These bounds fix the maximum contribution of neutrinos with primordial asymmetries to N{sub eff} as a function of the mixing parameter θ{sub 13}, and point out the upper bound N{sub eff}∼<3.4. Comparing these results with the forthcoming measurement of N{sub eff} by the Planck satellite will likely provide insight on the nature of the radiation content of the universe.

p-process nucleosynthesis via proton-capture reactions in thermonuclear supernovae explosions

Directory of Open Access Journals (Sweden)

Endres Anne

2015-01-01

Full Text Available Model calculations within the framework of the so-called γ process show an underproduction of the p nucleus with the highest isotopic abundace 92Mo. This discrepancy can be narrowed by taking into account the alternative production site of a type Ia supernova explosion. Here, the nucleus 92Mo can be produced by a sequence of proton-capture reactions. The amount of 92Mo nuclei produced via this reaction chain is most sensitive to the reactions 90Zr(p,γ and 91Nb(p,γ. Both rates have to be investigated experimentally to study the impact of this nucleosynthesis aspect on the long-standing 92Mo-problem. We have already measured the proton-capture reaction on 90Zr using high-resolution in-beam γ-ray spectroscopy. In this contribution, we will present our preliminary results of the total cross sections as well as the partial cross sections. Furthermore, we plan to measure the 91Nb(p,γ reaction soon. Due to the radioactive target material, the 91Nb nuclei have to be produced prior to the experiment. The current status of this production will be presented in this contribution.

The chemical evolution of galaxies

International Nuclear Information System (INIS)

Chiosi, Cesare

1986-01-01

The chemical evolution of galaxies is reviewed with particular attention to the theoretical interpretation of the distribution and abundances of elements in stars and the interstellar medium. The paper was presented to the conference on ''The early universe and its evolution'', Erice, Italy, 1986. The metallicity distribution of the solar vicinity, age metallicity relationship, abundance gradients in the galaxy, external galaxies, star formation and evolution, major sites of nucleosynthesis, yields of chemical elements, chemical models, and the galactic disk, are all discussed. (U.K.)

Inflaton and metric fluctuations in the early universe from a 5D vacuum state

Energy Technology Data Exchange (ETDEWEB)

Membiela, Agustin [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350 (7600) Mar del Plata (Argentina)]. E-mail: membiela@argentina.com; Bellini, Mauricio [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350 (7600) Mar del Plata (Argentina) and Consejo Nacional de Ciencia y Tecnologia (CONICET) (Argentina)]. E-mail: mbellini@mdp.edu.ar

2006-04-20

In this Letter we complete a previously introduced formalism to study the gauge-invariant metric fluctuations from a noncompact Kaluza-Klein theory of gravity, to study the evolution of the early universe. The evolution of both, metric and inflaton field fluctuations are reciprocally related. We obtain that <{delta}{rho}>/{rho}{sub b} depends on the coupling of {phi} with {delta}{phi} and the spectral index of its spectrum is 0.9483

Impact of (α, n) reactions on the nucleosynthesis in neutrino-driven winds

Energy Technology Data Exchange (ETDEWEB)

Bliss, Julia [Institut fuer Kernphysik, TU Darmstadt (Germany); Arcones, Almudena [Institut fuer Kernphysik, TU Darmstadt (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH (Germany); Montes, Fernando; Pereira, Jorge [National Superconducting Cyclotron Laboratory, Michigan State University (United States); Joint Institute for Nuclear Astrophysics (United States)

2015-07-01

Neutrino-driven winds that follow core-collapse supernova explosions are an exciting astrophysical site for the synthesis of heavy elements. Although recent hydrodynamical simulations show that the conditions in the wind are not extreme enough for a r-process up to uranium, neutrino-driven winds may be the astrophysical site where lighter heavy elements between Sr and Ag are produced. However, it is still not clear if the conditions in the wind are slightly neutron-rich, proton-rich or turn proton-rich for some time. In neutron-rich winds, (α,n) reactions are key to move matter beyond the Fe-group towards heavier elements. Due to the deficit of experimental information, the relevant reaction rates have mostly been calculated with codes based on Hauser-Feshbach models. Although these codes have been cross-checked with experimental data in regions close to stability, their accuracy is questionable as one moves towards more exotic regions. We present the impact of (α,n) reactions on the nucleosynthesis of elements between Sr and Ag in neutrino-driven winds.

Deep-Ocean Crusts as Telescopes: Using Live Radioisotopes to Probe Supernova Nucleosynthesis

CERN Document Server

Fields, B D; Ellis, Jonathan Richard; Fields, Brian D.; Hochmuth, Kathrin A.; Ellis, John

2005-01-01

Live 60Fe has recently been detected in a deep-ocean ferromanganese crust, isolated in layers dating from about 3 Myr ago. Since 60Fe has a mean life of 2.2 Myr, a near-Earth supernova is the only likely source for such a signal, and we explore here the consequences of a supernova origin. We combine the 60Fe data with several supernova nucleosynthesis models to calculate the supernova distance as a function of progenitor mass, finding an allowed range of 15-120 pc. We also predict the signals expected for several other radioisotopes, which are independent of the supernova distance. Species likely to be present near or above background levels are 10Be, 26Al, 53Mn, 182Hf and 244Pu. Of these, 182Hf and 244Pu are nearly background-free, presenting the best opportunities to provide strong confirmation of the supernova origin of the 60Fe signal, and to demonstrate that at least some supernovae are the source for the r-process. The accuracies of our predictions are hampered by large uncertainties in the predicted 60...

The r-process nucleosynthesis during the decompression of neutron star crust material

Energy Technology Data Exchange (ETDEWEB)

Goriely, S. [Institut d' Astronomie et d' Astrophysique, CP-226, Université Libre de Bruxelles, 1050 Brussels (Belgium); Bauswein, A. [Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece and Max-Planck-Institut für Astrophysik, Postfach 1317, 85741 Garching (Germany); Janka, H.-T. [Max-Planck-Institut für Astrophysik, Postfach 1317, 85741 Garching (Germany); Sida, J.-L.; Lemaître, J.-F.; Panebianco, S. [C.E.A. Saclay, Irfu/Service de Physique Nucléaire, 91191 Gif-sur-Yvette (France); Dubray, N.; Hilaire, S. [CEA, DAM, DIF, F-91297 Arpajon (France)

2014-05-02

About half of the nuclei heavier than iron observed in nature are produced by the so-called rapid neutron capture process, or r-process, of nucleosynthesis. The identification of the astrophysics site and the specific conditions in which the r-process takes place remains, however, one of the still-unsolved mysteries of modern astrophysics. Another underlying difficulty associated with our understanding of the r-process concerns the uncertainties in the predictions of nuclear properties for the few thousands exotic neutron-rich nuclei involved, for which essentially no experimental data exist. The present paper emphasizes some important future challenges faced by nuclear physics in this problem, particularly in the determination of the nuclear structure properties of exotic neutron-rich nuclei as well as their radiative neutron capture rates and their fission probabilities. These quantities are particularly relevant to determine the composition of the matter resulting from the r-process. Both the astrophysics and the nuclear physics difficulties are critically reviewed with special attention paid to the r-process taking place during the decompression of neutron star matter following the merging of two neutron stars.

Separating the early universe from the late universe: Cosmological parameter estimation beyond the black box

International Nuclear Information System (INIS)

Tegmark, Max; Zaldarriaga, Matias

2002-01-01

We present a method for measuring the cosmic matter budget without assumptions about speculative early Universe physics, and for measuring the primordial power spectrum P * (k) nonparametrically, either by combining CMB and LSS information or by using CMB polarization. Our method complements currently fashionable 'black box' cosmological parameter analysis, constraining cosmological models in a more physically intuitive fashion by mapping measurements of CMB, weak lensing and cluster abundance into k space, where they can be directly compared with each other and with galaxy and Lyα forest clustering. Including the new CBI results, we find that CMB measurements of P(k) overlap with those from 2dF galaxy clustering by over an order of magnitude in scale, and even overlap with weak lensing measurements. We describe how our approach can be used to raise the ambition level beyond cosmological parameter fitting as data improves, testing rather than assuming the underlying physics

Magnetic fields and chiral asymmetry in the early hot universe

Energy Technology Data Exchange (ETDEWEB)

Sydorenko, Maksym; Shtanov, Yuri [Bogolyubov Institute for Theoretical Physics, 03680 Kiev (Ukraine); Tomalak, Oleksandr, E-mail: maxsydorenko@gmail.com, E-mail: tomalak@uni-mainz.de, E-mail: shtanov@bitp.kiev.ua [Institut für Kernphysik, Johannes Gutenberg Universität, 55128 Mainz (Germany)

2016-10-01

In this paper, we study analytically the process of external generation and subsequent free evolution of the lepton chiral asymmetry and helical magnetic fields in the early hot universe. This process is known to be affected by the Abelian anomaly of the electroweak gauge interactions. As a consequence, chiral asymmetry in the fermion distribution generates magnetic fields of non-zero helicity, and vice versa. We take into account the presence of thermal bath, which serves as a seed for the development of instability in magnetic field in the presence of externally generated lepton chiral asymmetry. The developed helical magnetic field and lepton chiral asymmetry support each other, considerably prolonging their mutual existence, in the process of 'inverse cascade' transferring magnetic-field power from small to large spatial scales. For cosmologically interesting initial conditions, the chiral asymmetry and the energy density of helical magnetic field are shown to evolve by scaling laws, effectively depending on a single combined variable. In this case, the late-time asymptotics of the conformal chiral chemical potential reproduces the universal scaling law previously found in the literature for the system under consideration. This regime is terminated at lower temperatures because of scattering of electrons with chirality change, which exponentially washes out chiral asymmetry. We derive an expression for the termination temperature as a function of the chiral asymmetry and energy density of helical magnetic field.

Magnetic fields and chiral asymmetry in the early hot universe

International Nuclear Information System (INIS)

Sydorenko, Maksym; Shtanov, Yuri; Tomalak, Oleksandr

2016-01-01

In this paper, we study analytically the process of external generation and subsequent free evolution of the lepton chiral asymmetry and helical magnetic fields in the early hot universe. This process is known to be affected by the Abelian anomaly of the electroweak gauge interactions. As a consequence, chiral asymmetry in the fermion distribution generates magnetic fields of non-zero helicity, and vice versa. We take into account the presence of thermal bath, which serves as a seed for the development of instability in magnetic field in the presence of externally generated lepton chiral asymmetry. The developed helical magnetic field and lepton chiral asymmetry support each other, considerably prolonging their mutual existence, in the process of 'inverse cascade' transferring magnetic-field power from small to large spatial scales. For cosmologically interesting initial conditions, the chiral asymmetry and the energy density of helical magnetic field are shown to evolve by scaling laws, effectively depending on a single combined variable. In this case, the late-time asymptotics of the conformal chiral chemical potential reproduces the universal scaling law previously found in the literature for the system under consideration. This regime is terminated at lower temperatures because of scattering of electrons with chirality change, which exponentially washes out chiral asymmetry. We derive an expression for the termination temperature as a function of the chiral asymmetry and energy density of helical magnetic field.

Early Opportunities Research Partnership Between Howard University, University of Maryland Baltimore County and NASA Goddard for Engaging Underrepresented STEM Students in Earth and Space Sciences

Science.gov (United States)

Misra, P.; Venable, D. D.; Hoban, S.; Demoz, B.; Bleacher, L.; Meeson, B. W.; Farrell, W. M.

2017-12-01

Howard University, University of Maryland Baltimore County and NASA Goddard Space Flight Center (GSFC) are collaborating to engage underrepresented STEM students and expose them to an early career pathway in NASA-related Earth & Space Science research. The major goal is to instill interest in Earth and Space Science to STEM majors early in their academic careers, so that they become engaged in ongoing NASA-related research, motivated to pursue STEM careers, and perhaps become part of the future NASA workforce. The collaboration builds on a program established by NASA's Dynamic Response of the Environments of Asteroids, the Moon and the moons of Mars (DREAM2) team to engage underrepresented students from Howard in summer internships. Howard leveraged this program to expand via NASA's Minority University Research and Education Project (MUREP) funding. The project pairs Howard students with GSFC mentors and engages them in cutting-edge Earth and Space Science research throughout their undergraduate tenure. The project takes a multi-faceted approach, with each year of the program specifically tailored to each student's strengths and addressing their weaknesses, so that they experience a wide array of enriching research and professional development activities that help them grow both academically and professionally. During the academic year, the students are at Howard taking a full load of courses towards satisfying their degree requirements and engaging in research with their GSFC mentors via regular telecons, e-mail exchanges, video chats & on an average one visit per semester to GSFC for an in-person meeting with their research mentor. The students extend their research with full-time summer internships at GSFC, culminating in a Capstone Project and Senior Thesis. As a result, these Early Opportunities Program students, who have undergone rigorous training in the Earth and Space Sciences, are expected to be well-prepared for graduate school and the NASA workforce.

Accessibility of the pre-big-bang models to LIGO

International Nuclear Information System (INIS)

Mandic, Vuk; Buonanno, Alessandra

2006-01-01

The recent search for a stochastic background of gravitational waves with LIGO interferometers has produced a new upper bound on the amplitude of this background in the 100 Hz region. We investigate the implications of the current and future LIGO results on pre-big-bang models of the early Universe, determining the exclusion regions in the parameter space of the minimal pre-big-bang scenario. Although the current LIGO reach is still weaker than the indirect bound from big bang nucleosynthesis, future runs by LIGO, in the coming year, and by Advanced LIGO (∼2009) should further constrain the parameter space, and in some parts surpass the Big Bang nucleosynthesis bound. It will be more difficult to constrain the parameter space in nonminimal pre-big bang models, which are characterized by multiple cosmological phases in the yet not well understood stringy phase, and where the higher-order curvature and/or quantum-loop corrections in the string effective action should be included

Cosmological constraints on decoupled dark photons and dark Higgs

Energy Technology Data Exchange (ETDEWEB)

Berger, Joshua [Physics Department, University of Wisconsin-Madison,1150 University Ave, Madison, WI 53706 (United States); Jedamzik, Karsten [Laboratoire Univers et Particules de Montpellier, UMR5299-CNRS,Université Montpellier II,Place Eugène Bataillon, CC 72, 34095 Montpellier Cédex 05 (France); Walker, Devin G.E. [Department of Physics and Astronomy, Dartmouth College,6127 Wilder Laboratory, Hanover, NH 03755 (United States); Department of Physics, University of Washington,Box 351560, Seattle, WA 98195 (United States)

2016-11-16

Any neutral boson such as a dark photon or dark Higgs that is part of a non-standard sector of particles can mix with its standard model counterpart. When very weakly mixed with the Standard Model, these particles are produced in the early Universe via the freeze-in mechanism and subsequently decay back to standard model particles. In this work, we place constraints on such mediator decays by considering bounds from Big Bang nucleosynthesis and the cosmic microwave background radiation. We find both nucleosynthesis and CMB can constrain dark photons with a kinetic mixing parameter between log ϵ∼−10 to −17 for masses between 1 MeV and 100 GeV. Similarly, the dark Higgs mixing angle ϵ with the Standard Model Higgs is constrained between log ϵ∼−6 to −15. Dramatic improvement on the bounds from CMB spectral distortions can be achieved with proposed experiments such as PIXIE.

Integrated Specialized Early-Course Psychosis Treatment Services - University Psychiatric Hospital Vrapce Model.

Science.gov (United States)

Ostojić, DraŽenka; Čulo, Ilaria; Silić, Ante; Kos, Suzana; Savić, Aleksandar

2018-06-01

First episode of psychosis presents a critical period in terms of numerous associated risks, but also possibilities for effective therapeutic interventions. There is a continued focus on early interventions in prodromal states and early course of frank psychosis, aimed at ensuring faster remission, reducing relapses, achieving better long-term functioning, and preventing adverse outcomes linked to untreated psychosis and chronic psychotic disorders. A number of different specialized treatment models and services exist trying to close knowledge gaps and provide clinical interventions to first-episode psychosis (FEP) patients, but there is still no generally accepted standard of care informing our every-day practice. FEP and early-course psychosis specialized treatment model developed in 2004 in University Psychiatric Hospital Vrapce rests on integration of care across different organization units and clinical presentation acuity levels and patient needs (intensive care, FEP inpatient unit, FEP outpatient services including day hospital). Such integration of FEP services allows for flexible entry point on multiple levels, earlier structuring of therapeutic alliance for those requiring inpatient care, reduction of risks associated with FEP, quicker formation of long-term treatment plans, reduction of delay in accessing specialized services, and a more coordinated diagnostic process and recruitment of FEP patient population. Detailed evaluations of outcomes and comparisons with different treatment models are necessary in order to assess strengths and weaknesses of each specific model and inform modifications to current practice models.

Magnetic reheating

Science.gov (United States)

Saga, Shohei; Tashiro, Hiroyuki; Yokoyama, Shuichiro

2018-02-01

We provide a new bound on the amplitude of primordial magnetic fields (PMFs) by using a novel mechanism, magnetic reheating. The damping of the magnetohydrodynamics fluid motions in a primordial plasma brings the dissipation of the PMFs. In the early Universe with z ≳ 2 × 106, cosmic microwave background (CMB) photons are quickly thermalized with the dissipated energy and shift to a different Planck distribution with a new temperature. In other words, the PMF dissipation changes the baryon-to-photon number ratio, and we name such a process magnetic reheating. From the current baryon-to-photon number ratio obtained from the big bang nucleosynthesis and CMB observations, we put the strongest constraint on the PMFs on small scales which CMB observations cannot access, B0 ≲ 1.0 μG at the scales 104 generation mechanisms of PMFs in the early Universe.

Primordial black holes from scalar field evolution in the early universe

Science.gov (United States)

Cotner, Eric; Kusenko, Alexander

2017-11-01

Scalar condensates with large expectation values can form in the early universe, for example, in theories with supersymmetry. The condensate can undergo fragmentation into Q-balls before decaying. If the Q-balls dominate the energy density for some period of time, statistical fluctuations in their number density can lead to formation of primordial black holes (PBH). In the case of supersymmetry the mass range is limited from above by 1 023 g . For a general charged scalar field, this robust mechanism can generate black holes over a much broader mass range, including the black holes with masses of 1-100 solar masses, which is relevant for LIGO observations of gravitational waves. Topological defects can lead to formation of PBH in a similar fashion.

Using Electronic Portfolio to Promote Professional Learning Community for Pre-Service Early Childhood Teachers at Alquds University

Science.gov (United States)

Khales, Buad

2016-01-01

The present study aims to explore whether the electronic portfolio can influence pre-service teachers' education and to examine how professional learning communities develop through electronic portfolios. To achieve this, twenty-four student-teachers taking a course in early childhood education at Al-Quds University participated in a study to…

Cosmology and particle physics

Energy Technology Data Exchange (ETDEWEB)

Steigman, G [California Univ., Santa Barbara (USA). Inst. for Theoretical Physics; Bartol Research Foundation, Newark, Delaware (USA))

1982-01-29

The cosmic connections between physics on the very largest and very smallest scales are reviewed with an emphasis on the symbiotic relation between elementary particle physics and cosmology. After a review of the early Universe as a cosmic accelerator, various cosmological and astrophysical constraints on models of particle physics are outlined. To illustrate this approach to particle physics via cosmology, reference is made to several areas of current research: baryon non-conservation and baryon asymmetry; free quarks, heavy hadrons and other exotic relics; primordial nucleosynthesis and neutrino masses.

Encouraging entrepreneurship in university labs: Research activities, research outputs, and early doctorate careers.

Science.gov (United States)

Roach, Michael

2017-01-01

This paper investigates how the encouragement of entrepreneurship within university research labs relates with research activities, research outputs, and early doctorate careers. Utilizing a panel survey of 6,840 science & engineering doctoral students at 39 R1 research universities, this study shows that entrepreneurship is widely encouraged across university research labs, ranging from 54% in biomedical engineering to 18% in particle physics, while only a small share of labs openly discourage entrepreneurship, from approximately 3% in engineering to approximately 12% in the life sciences. Within fields, there is no difference between labs that encourage entrepreneurship and those that do not with respect to basic research activity and the number of publications. At the same time, labs that encourage entrepreneurship are significantly more likely to report invention disclosures, particularly in engineering where such labs are 41% more likely to disclose inventions. With respect to career pathways, PhDs students in labs that encourage entrepreneurship do not differ from other PhDs in their interest in academic careers, but they are 87% more likely to be interested in careers in entrepreneurship and 44% more likely to work in a startup after graduation. These results persist even when accounting for individuals' pre-PhD interest in entrepreneurship and the encouragement of other non-academic industry careers.

Encouraging entrepreneurship in university labs: Research activities, research outputs, and early doctorate careers

Science.gov (United States)

2017-01-01

This paper investigates how the encouragement of entrepreneurship within university research labs relates with research activities, research outputs, and early doctorate careers. Utilizing a panel survey of 6,840 science & engineering doctoral students at 39 R1 research universities, this study shows that entrepreneurship is widely encouraged across university research labs, ranging from 54% in biomedical engineering to 18% in particle physics, while only a small share of labs openly discourage entrepreneurship, from approximately 3% in engineering to approximately 12% in the life sciences. Within fields, there is no difference between labs that encourage entrepreneurship and those that do not with respect to basic research activity and the number of publications. At the same time, labs that encourage entrepreneurship are significantly more likely to report invention disclosures, particularly in engineering where such labs are 41% more likely to disclose inventions. With respect to career pathways, PhDs students in labs that encourage entrepreneurship do not differ from other PhDs in their interest in academic careers, but they are 87% more likely to be interested in careers in entrepreneurship and 44% more likely to work in a startup after graduation. These results persist even when accounting for individuals’ pre-PhD interest in entrepreneurship and the encouragement of other non-academic industry careers. PMID:28178270

From cosmos to intelligent life: the four ages of astrobiology

Science.gov (United States)

Gleiser, Marcelo

2012-10-01

The history of life on Earth and in other potential life-bearing planetary platforms is deeply linked to the history of the Universe. Since life, as we know, relies on chemical elements forged in dying heavy stars, the Universe needs to be old enough for stars to form and evolve. The current cosmological theory indicates that the Universe is 13.7 +/- 0.13 billion years old and that the first stars formed hundreds of millions of years after the Big Bang. At least some stars formed with stable planetary systems wherein a set of biochemical reactions leading to life could have taken place. In this paper, I argue that we can divide cosmological history into four ages, from the Big Bang to intelligent life. The physical age describes the origin of the Universe, of matter, of cosmic nucleosynthesis, as well as the formation of the first stars and Galaxies. The chemical age began when heavy stars provided the raw ingredients for life through stellar nucleosynthesis and describes how heavier chemical elements collected in nascent planets and Moons gave rise to prebiotic biomolecules. The biological age describes the origin of early life, its evolution through Darwinian natural selection and the emergence of complex multicellular life forms. Finally, the cognitive age describes how complex life evolved into intelligent life capable of self-awareness and of developing technology through the directed manipulation of energy and materials. I conclude discussing whether we are the rule or the exception.

About the role of Higgs boson in the evolution of the early universe

International Nuclear Information System (INIS)

Jegerlehner, Fred

2014-06-01

After the discovery of the Higgs particle the most relevant structures of the SM have been verified and for the first time we know all parameters of the SM within remarkable accuracy. Together with recent calculations of the SM renormalization group coefficients up to three loops we can safely extrapolate running couplings high up in energy. Assuming that the SM is a low energy effective theory of a cutoff theory residing at the Planck scale, we are able to calculate the effective bare parameters of the underlying cutoff system. It turns out that the effective bare mass term changes sign not far below the Planck scale, which means that in the early universe the SM was in the symmetric phase. The sign-flip, which is a result of a conspiracy between the SM couplings and their screening/antiscreening behavior, triggers the Higgs mechanism. Above the Higgs phase transition the bare mass term in the Higgs potential must have had a large positive value, enhanced by the quadratic divergence of the bare Higgs mass. Likewise the quartically enhanced positive vacuum energy density is present in the symmetric phase. The Higgs system thus provides the large dark energy density in the early universe, which triggers slow-roll inflation, i.e. the SM Higgs is the inflaton scalar field. Reheating is dominated by the decay of the heavy Higgses into (in the symmetric phase) massless top/anti-top quark pairs. The new scenario possibly could explain the baryon-asymmetry essentially in terms of SM physics.

Cosmology with hybrid expansion law: scalar field reconstruction of cosmic history and observational constraints

International Nuclear Information System (INIS)

Akarsu, Özgür; Kumar, Suresh; Myrzakulov, R.; Sami, M.; Xu, Lixin

2014-01-01

In this paper, we consider a simple form of expansion history of Universe referred to as the hybrid expansion law - a product of power-law and exponential type of functions. The ansatz by construction mimics the power-law and de Sitter cosmologies as special cases but also provides an elegant description of the transition from deceleration to cosmic acceleration. We point out the Brans-Dicke realization of the cosmic history under consideration. We construct potentials for quintessence, phantom and tachyon fields, which can give rise to the hybrid expansion law in general relativity. We investigate observational constraints on the model with hybrid expansion law applied to late time acceleration as well as to early Universe a la nucleosynthesis

Probing the early universe with inflationary gravitational waves

International Nuclear Information System (INIS)

Boyle, Latham A.; Steinhardt, Paul J.

2008-01-01

Near comoving wave number k, the gravitational-wave background (GWB) from inflation carries information about the physical conditions near two moments in cosmic history: the moment when k 'left the horizon' during inflation, and the moment when it 're-entered the horizon' after inflation. We investigate the extent to which this information can be extracted if the GWB is measured by a combination of cosmic-microwave-background polarization experiments on large scales and space-based laser-interferometer experiments on small scales. To disentangle this information, we derive a new gravitational-wave transfer function that incorporates a number of physical effects that were treated less accurately, less generally, or were missing altogether in previous treatments. In particular, it incorporates: (i) dark energy with time-varying equation of state w(z); (ii) tensor anisotropic stress due to free-streaming relativistic particles in the early universe; and (iii) a variety of physical effects that cause deviations from the standard equation of state w=1/3 during the radiation era. Based on this transfer function, we consider the degree to which the GWB can be used to test inflation and to probe the 'primordial dark age' between the end of inflation and the electroweak phase transition.

Home and Community Language Proficiency in Spanish-English Early Bilingual University Students.

Science.gov (United States)

Schmidtke, Jens

2017-10-17

This study assessed home and community language proficiency in Spanish-English bilingual university students to investigate whether the vocabulary gap reported in studies of bilingual children persists into adulthood. Sixty-five early bilinguals (mean age = 21 years) were assessed in English and Spanish vocabulary and verbal reasoning ability using subtests of the Woodcock-Muñoz Language Survey-Revised (Schrank & Woodcock, 2009). Their English scores were compared to 74 monolinguals matched in age and level of education. Participants also completed a background questionnaire. Bilinguals scored below the monolingual control group on both subtests, and the difference was larger for vocabulary compared to verbal reasoning. However, bilinguals were close to the population mean for verbal reasoning. Spanish scores were on average lower than English scores, but participants differed widely in their degree of balance. Participants with an earlier age of acquisition of English and more current exposure to English tended to be more dominant in English. Vocabulary tests in the home or community language may underestimate bilingual university students' true verbal ability and should be interpreted with caution in high-stakes situations. Verbal reasoning ability may be more indicative of a bilingual's verbal ability.

Evidence for supernova injection into the solar nebula and the decoupling of r-process nucleosynthesis.

Science.gov (United States)

Brennecka, Gregory A; Borg, Lars E; Wadhwa, Meenakshi

2013-10-22

The isotopic composition of our Solar System reflects the blending of materials derived from numerous past nucleosynthetic events, each characterized by a distinct isotopic signature. We show that the isotopic compositions of elements spanning a large mass range in the earliest formed solids in our Solar System, calcium-aluminum-rich inclusions (CAIs), are uniform, and yet distinct from the average Solar System composition. Relative to younger objects in the Solar System, CAIs contain positive r-process anomalies in isotopes A 140. This fundamental difference in the isotopic character of CAIs around mass 140 necessitates (i) the existence of multiple sources for r-process nucleosynthesis and (ii) the injection of supernova material into a reservoir untapped by CAIs. A scenario of late supernova injection into the protoplanetary disk is consistent with formation of our Solar System in an active star-forming region of the galaxy.

Study of the concordance of a matter-antimatter symmetric Dirac-Milne Universe

International Nuclear Information System (INIS)

Benoit-Levy, A.

2009-09-01

This thesis is devoted to the study of the Dirac-Milne Universe, a cosmological model in which matter and antimatter are present in equal quantities and where antimatter, as suggested by general relativity through the properties of the Kerr-Newman solutions, is supposed to have a negative active gravitational mass. Supposing such hypothesis removes the necessity to invoke inflation, Dark Energy and Dark matter as mandatory components. Matter (with positive mass) and antimatter (with negative mass) being present in equal quantities, the scale factor evolves linearly with time. After a short summary of basic properties of standard cosmology, some consequences of this linear evolution are studied. The full study of primordial nucleosynthesis within the framework of the Dirac-Milne universe reveals that deuterium can be produced by residual annihilations between matter and antimatter shortly before recombination. Even though Dirac-Milne universe does not present any recent acceleration of the expansion, it is shown that this model is in good agreement with the cosmological test of type Ia supernovae. It is also shown that the position of the acoustic scale of the Cosmic Microwave Background (CMB) naturally appears at the degree scale. The full study of the CMB spectrum and the coherence of the notion of negative mass remain to be investigated, but this work exhibits a original model that could potentially give an alternative description of our Universe. (author)

Late time acceleration of the 3-space in a higher dimensional steady state universe in dilaton gravity

International Nuclear Information System (INIS)

Akarsu, Özgür; Dereli, Tekin

2013-01-01

We present cosmological solutions for (1+3+n)-dimensional steady state universe in dilaton gravity with an arbitrary dilaton coupling constant w and exponential dilaton self-interaction potentials in the string frame. We focus particularly on the class in which the 3-space expands with a time varying deceleration parameter. We discuss the number of the internal dimensions and the value of the dilaton coupling constant to determine the cases that are consistent with the observed universe and the primordial nucleosynthesis. The 3-space starts with a decelerated expansion rate and evolves into accelerated expansion phase subject to the values of w and n, but ends with a Big Rip in all cases. We discuss the cosmological evolution in further detail for the cases w = 1 and w = ½ that permit exact solutions. We also comment on how the universe would be conceived by an observer in four dimensions who is unaware of the internal dimensions and thinks that the conventional general relativity is valid at cosmological scales

Late time acceleration of the 3-space in a higher dimensional steady state universe in dilaton gravity

Science.gov (United States)

Akarsu, Özgür; Dereli, Tekin

2013-02-01

We present cosmological solutions for (1+3+n)-dimensional steady state universe in dilaton gravity with an arbitrary dilaton coupling constant w and exponential dilaton self-interaction potentials in the string frame. We focus particularly on the class in which the 3-space expands with a time varying deceleration parameter. We discuss the number of the internal dimensions and the value of the dilaton coupling constant to determine the cases that are consistent with the observed universe and the primordial nucleosynthesis. The 3-space starts with a decelerated expansion rate and evolves into accelerated expansion phase subject to the values of w and n, but ends with a Big Rip in all cases. We discuss the cosmological evolution in further detail for the cases w = 1 and w = ½ that permit exact solutions. We also comment on how the universe would be conceived by an observer in four dimensions who is unaware of the internal dimensions and thinks that the conventional general relativity is valid at cosmological scales.

Early cosmology constrained

Energy Technology Data Exchange (ETDEWEB)

Verde, Licia; Jimenez, Raul [Institute of Cosmos Sciences, University of Barcelona, IEEC-UB, Martí Franquès, 1, E08028 Barcelona (Spain); Bellini, Emilio [University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom); Pigozzo, Cassio [Instituto de Física, Universidade Federal da Bahia, Salvador, BA (Brazil); Heavens, Alan F., E-mail: liciaverde@icc.ub.edu, E-mail: emilio.bellini@physics.ox.ac.uk, E-mail: cpigozzo@ufba.br, E-mail: a.heavens@imperial.ac.uk, E-mail: raul.jimenez@icc.ub.edu [Imperial Centre for Inference and Cosmology (ICIC), Imperial College, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom)

2017-04-01

We investigate our knowledge of early universe cosmology by exploring how much additional energy density can be placed in different components beyond those in the ΛCDM model. To do this we use a method to separate early- and late-universe information enclosed in observational data, thus markedly reducing the model-dependency of the conclusions. We find that the 95% credibility regions for extra energy components of the early universe at recombination are: non-accelerating additional fluid density parameter Ω{sub MR} < 0.006 and extra radiation parameterised as extra effective neutrino species 2.3 < N {sub eff} < 3.2 when imposing flatness. Our constraints thus show that even when analyzing the data in this largely model-independent way, the possibility of hiding extra energy components beyond ΛCDM in the early universe is seriously constrained by current observations. We also find that the standard ruler, the sound horizon at radiation drag, can be well determined in a way that does not depend on late-time Universe assumptions, but depends strongly on early-time physics and in particular on additional components that behave like radiation. We find that the standard ruler length determined in this way is r {sub s} = 147.4 ± 0.7 Mpc if the radiation and neutrino components are standard, but the uncertainty increases by an order of magnitude when non-standard dark radiation components are allowed, to r {sub s} = 150 ± 5 Mpc.

The history of the universe

CERN Document Server

Lyth, David H

2016-01-01

This book gives an accessible account of the history of the Universe; not only what happened, but why it happened. An author of textbooks on the early Universe and inflation, David Lyth now explains both cosmology and the underlying physics to the general reader. The book includes a detailed account of the almost imperceptible structure in the early Universe, and its probable origin as a quantum fluctuation during an early epoch known as the epoch of inflation. It also explains how that early structure is visible now in the cosmic microwave radiation which is our main source of information about the early Universe, and how it gave rise to galaxies and stars. The main text of the book assumes no knowledge of mathematics or physics so that it is accessible to everybody, while an appendix contains more advanced material. As a result the book will be useful for a wide spectrum of readers, including high-school students, undergraduates, postgraduates and professional physicists working in areas other than cosmolo...

Encouraging entrepreneurship in university labs: Research activities, research outputs, and early doctorate careers.

Directory of Open Access Journals (Sweden)

Michael Roach

Full Text Available This paper investigates how the encouragement of entrepreneurship within university research labs relates with research activities, research outputs, and early doctorate careers. Utilizing a panel survey of 6,840 science & engineering doctoral students at 39 R1 research universities, this study shows that entrepreneurship is widely encouraged across university research labs, ranging from 54% in biomedical engineering to 18% in particle physics, while only a small share of labs openly discourage entrepreneurship, from approximately 3% in engineering to approximately 12% in the life sciences. Within fields, there is no difference between labs that encourage entrepreneurship and those that do not with respect to basic research activity and the number of publications. At the same time, labs that encourage entrepreneurship are significantly more likely to report invention disclosures, particularly in engineering where such labs are 41% more likely to disclose inventions. With respect to career pathways, PhDs students in labs that encourage entrepreneurship do not differ from other PhDs in their interest in academic careers, but they are 87% more likely to be interested in careers in entrepreneurship and 44% more likely to work in a startup after graduation. These results persist even when accounting for individuals' pre-PhD interest in entrepreneurship and the encouragement of other non-academic industry careers.

Domain Walls and Matter-Antimatter Domains in the Early Universe

Directory of Open Access Journals (Sweden)

Dolgov A.D.

2017-01-01

Full Text Available We suggest a scenario of spontaneous (or dynamical C and CP violation according to which it is possible to generate domains of matter and antimatter separated by cosmologically large distances. Such C(CP violation existed only in the early universe and later it disappeared with the only trace of generated matter and antimatter domains. So this scenario does not suffer from the problem of domain walls. According to this scenario the width of the domain wall should grow exponentially to prevent annihilation at the domain boundaries. Though there is a classical result obtained by Basu and Vilenkin that the width of the wall tends to the one of the stationary solution (constant physical width. That is why we considered thick domain walls in a de Sitter universe following paper by Basu and Vilenkin. However, we were interested not only in stationary solutions found therein, but also investigated the general case of domain wall evolution with time. When the wall thickness parameter, δ0 , is smaller than H−1/2 where H is the Hubble parameter in de Sitter space-time, then the stationary solutions exist, and initial field configurations tend with time to the stationary ones. However, there are no stationary solutions for δ0>H−1/2 We have calculated numerically the rate of the wall expansion in this case and have found that the width of the wall grows exponentially fast for δ0≫H−1 An explanation for the critical value δ0c=H−1/2 is also proposed.

Early universe with modified scalar-tensor theory of gravity

Science.gov (United States)

Mandal, Ranajit; Sarkar, Chandramouli; Sanyal, Abhik Kumar

2018-05-01

Scalar-tensor theory of gravity with non-minimal coupling is a fairly good candidate for dark energy, required to explain late-time cosmic evolution. Here we study the very early stage of evolution of the universe with a modified version of the theory, which includes scalar curvature squared term. One of the key aspects of the present study is that, the quantum dynamics of the action under consideration ends up generically with de-Sitter expansion under semiclassical approximation, rather than power-law. This justifies the analysis of inflationary regime with de-Sitter expansion. The other key aspect is that, while studying gravitational perturbation, the perturbed generalized scalar field equation obtained from the perturbed action, when matched with the perturbed form of the background scalar field equation, relates the coupling parameter and the potential exactly in the same manner as the solution of classical field equations does, assuming de-Sitter expansion. The study also reveals that the quantum theory is well behaved, inflationary parameters fall well within the observational limit and quantum perturbation analysis shows that the power-spectrum does not deviate considerably from the standard one obtained from minimally coupled theory.

GUTs and supersymmetric GUTs in the very early universe

International Nuclear Information System (INIS)

Ellis, J.

1982-10-01

This talk is intended as background material for many of the other talks treating the possible applications of GUTs to the very early universe. I start with a review of the present theoretical and phenomenological status of GUTs before going on to raise some new issues for their prospective cosmological applications which arise in supersymmetric (susy) GUTs. The first section is an update on conventional GUTs, which is followed by a reminder of some of the motivations for going supersymmetric. There then follows a simple primer on susy and a discussion of the structure and phenomenology of simple sysy GUTs. Finally we come to the cosmological issues, including problems arising from the degeneracy of susy minima, baryosynthesis and supersymmetric inflation, the possibility that gravity is an essential complication in constructing susy GUTs and discussing their cosmology, and the related question of what mass range is allowed for the gravitino. Several parts of this write-up contain new material which has emerged either during the Workshop or subsequently. They are included here for completeness and the convenience of the prospective reader. Wherever possible, these anachronisms will be flagged so as to keep straight the historical record

Rapid growth of seed black holes in the early universe by supra-exponential accretion.

Science.gov (United States)

Alexander, Tal; Natarajan, Priyamvada

2014-09-12

Mass accretion by black holes (BHs) is typically capped at the Eddington rate, when radiation's push balances gravity's pull. However, even exponential growth at the Eddington-limited e-folding time t(E) ~ few × 0.01 billion years is too slow to grow stellar-mass BH seeds into the supermassive luminous quasars that are observed when the universe is 1 billion years old. We propose a dynamical mechanism that can trigger supra-exponential accretion in the early universe, when a BH seed is bound in a star cluster fed by the ubiquitous dense cold gas flows. The high gas opacity traps the accretion radiation, while the low-mass BH's random motions suppress the formation of a slowly draining accretion disk. Supra-exponential growth can thus explain the puzzling emergence of supermassive BHs that power luminous quasars so soon after the Big Bang. Copyright © 2014, American Association for the Advancement of Science.

"Swim or Sink": State of Induction in the Deployment of Early Career Academics into Teaching at Makerere University

Science.gov (United States)

Ssempebwa, Jude; Teferra, Damtew; Bakkabulindi, Fred Edward K.

2016-01-01

Conducted as part of a multi-country study of the teaching-related experiences and expectations of early career academics (ECAs) in Africa, this study investigated the major influences on the teaching practice of ECAs at Makerere University; the mechanisms by which these academics learn to teach; the teaching-related challenges they experience;…

Big-Bang Nucleosynthesis with Negatively-Charged Massive Particles as a Cosmological Solution to the 6Li and 7Li Problems

International Nuclear Information System (INIS)

Kusakabe, Motohiko; Kajino, Toshitaka; Boyd, Richard N.; Yoshida, Takashi; Mathews, Grant J.

2008-01-01

Observations of metal poor halo stars exhibit a possible plateau of 6 Li abundance as a function of metallicity similar to that for 7 Li, suggesting a big bang origin. However, the inferred primordial abundance of 6 Li is ∼1000 times larger than that predicted by standard big bang nucleosynthesis (BBN) for the baryon-to-photon ratio inferred from the WMAP data. On the other hand, the inferred 7 Li primordial abundance is about 3 times smaller than the prediction. We study a possible simultaneous solution to both the problems of underproduction of 6 Li and overproduction of 7 Li in BBN. This solution involves a hypothetical massive, negatively-charged leptonic particle that would bind to the light nuclei produced in BBN, but would decay long before it could be detected. Because the particle gets bound to the existing nuclei after the cessation of the usual big bang nuclear reactions, a second longer epoch of nucleosynthesis can occur among X-nuclei which have reduced Coulomb barriers. We numerically carry out a fully dynamical BBN calculation, simultaneously solving the recombination and ionization processes of negatively-charged particles by normal and X-nuclei as well as many possible nuclear reactions among them. We confirm that a reaction in which the hypothetical particle is transferred can occur that greatly enhance the production of 6 Li while a reaction through an atomic excited state of X-nucleus depletes 7 Li. It is confirmed that BBN in the presence of these hypothetical particles, together with or without an event of stellar burning process, can simultaneously solve the two Li abundance problems

Cosmic-Ray Nucleosynthesis of p-nuclei: Yields and Routes

Science.gov (United States)

Kusakabe, Motohiko; Mathews, Grant J.

2018-02-01

We investigate the cosmic-ray nucleosynthesis (CRN) of proton-rich stable nuclides (p-nuclides). We calculate the cosmic-ray (CR) energy spectra of heavy nuclides with mass number A=[74,209], taking into account the detailed nuclear spallation, decay, energy loss, and escape from the Galaxy during the CR propagation. We adopt the latest semiempirical formula SPACS for the spallation cross sections and the latest data on nuclear decay. Effective electron-capture decay rates are calculated using the proper cross sections for recombination and ionization in the whole CR energy region. Calculated CR spectral shapes vary for different nuclides. Abundances of proton-rich unstable nuclides increase in CRs with increasing energy relative to those of other nuclides. Yields of the primary and secondary spallation processes and differential yields from respective seed nuclides are calculated. We find that the CR energy region of ≤slant { \\mathcal O }(100) MeV/nucleon predominantly contributes to the total yields. The atomic cross sections in the low-energy range adopted in this study are then necessary. Effects of CRN on the Galactic chemical evolution of p-nuclides are calculated. Important seed nuclides are identified for respective p-nuclides. The contribution of CRN is significant for 180m Ta, accounting for about 20% of the solar abundance. About 87% of the 180m Ta CRN yield can be attributed to the primary process. The most important production routes are reactions of 181Ta, 180Hf, and 182W. CRN yields of other p-nuclides are typically about { \\mathcal O }(10‑4–10‑2) of solar abundances.

Massive boson-fermion degeneracy and the early structure of the universe

International Nuclear Information System (INIS)

Kounnas, C.

2008-01-01

The existence of a new kind of massive boson-fermion symmetry is shown explicitly in the framework of the heterotic, type II and type II orientifold superstring theories. The target space-time is two-dimensional. Higher dimensional models are defined via large marginal deformations of J anti J-type. The spectrum of the initial undeformed two dimensional vacuum consists of massless boson degrees of freedom, while all massive boson and fermion degrees of freedom exhibit a new Massive Spectrum Degeneracy Symmetry (MSDS). This precise property, distinguishes the MSDS theories from the well known supersymmetric SUSY-theories. Some proposals are stated in the framework of these theories concerning the structure of: (i) The Early Non-singular Phase of the Universe, (ii) The two dimensional boundary theory of AdS 3 Black-Holes, (iii) Plausible applications of the MSDS theories in particle physics, alternative to SUSY. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

E.M. Freeman: early research on cereal diseases and the rise of plant pathology at the University of Minnesota.

Science.gov (United States)

Peterson, P D

2001-01-01

E.M. Freeman's role in early cereal disease research and the beginning of plant pathology at the University of Minnesota has been overshadowed largely by the enormous prestige of his student, E.C. Stakman. During the first decade of the twentieth century, Freeman was responsible for the transferral from Europe to the United States and the subsequent nurturing of important conceptual and technical developments in the area of cereal disease pathology. Under Freeman's leadership, these ideas would come to shape the direction of plant pathology research at the University of Minnesota for decades to follow.

Constraining strong baryon-dark-matter interactions with primordial nucleosynthesis and cosmic rays

International Nuclear Information System (INIS)

Cyburt, Richard H.; Fields, Brian D.; Pavlidou, Vasiliki; Wandelt, Benjamin

2002-01-01

Self-interacting dark matter (SIDM) was introduced by Spergel and Steinhardt to address possible discrepancies between collisionless dark matter simulations and observations on scales of less than 1 Mpc. We examine the case in which dark matter particles not only have strong self-interactions but also have strong interactions with baryons. The presence of such interactions will have direct implications for nuclear and particle astrophysics. Among these are a change in the predicted abundances from big bang nucleosynthesis (BBN) and the flux of γ rays produced by the decay of neutral pions which originate in collisions between dark matter and galactic cosmic rays (CR). From these effects we constrain the strength of the baryon-dark-matter interactions through the ratio of baryon-dark-matter interaction cross section to dark matter mass, s. We find that BBN places a weak upper limit on this ratio (less-or-similar sign)10 8 cm 2 g -1 . CR-SIDM interactions, however, limit the possible DM-baryon cross section to (less-or-similar sign)5x10 -3 cm 2 g -1 ; this rules out an energy-independent interaction, but not one which falls with center-of-mass velocity s∝1/v or steeper

Energy Feedback from X-ray Binaries in the Early Universe

Science.gov (United States)

Fragos, T.; Lehmer, B..; Naoz, S.; Zezas, A.; Basu-Zych, A.

2013-01-01

X-ray photons, because of their long mean-free paths, can easily escape the galactic environments where they are produced, and interact at long distances with the intergalactic medium, potentially having a significant contribution to the heating and reionization of the early universe. The two most important sources of X-ray photons in the universe are active galactic nuclei (AGNs) and X-ray binaries (XRBs). In this Letter we use results from detailed, large scale population synthesis simulations to study the energy feedback of XRBs, from the first galaxies (z (redshift) approximately equal to 20) until today.We estimate that X-ray emission from XRBs dominates over AGN at z (redshift) greater than or approximately equal to 6-8. The shape of the spectral energy distribution of the emission from XRBs shows little change with redshift, in contrast to its normalization which evolves by approximately 4 orders of magnitude, primarily due to the evolution of the cosmic star-formation rate. However, the metallicity and the mean stellar age of a given XRB population affect significantly its X-ray output. Specifically, the X-ray luminosity from high-mass XRBs per unit of star-formation rate varies an order of magnitude going from solar metallicity to less than 10% solar, and the X-ray luminosity from low-mass XRBs per unit of stellar mass peaks at an age of approximately 300 Myr (million years) and then decreases gradually at later times, showing little variation for mean stellar ages 3 Gyr (Giga years, or billion years). Finally, we provide analytical and tabulated prescriptions for the energy output of XRBs, that can be directly incorporated in cosmological simulations.

Sterile neutrino dark matter with supersymmetry

Science.gov (United States)

Shakya, Bibhushan; Wells, James D.

2017-08-01

Sterile neutrino dark matter, a popular alternative to the WIMP paradigm, has generally been studied in non-supersymmetric setups. If the underlying theory is supersymmetric, we find that several interesting and novel dark matter features can arise. In particular, in scenarios of freeze-in production of sterile neutrino dark matter, its superpartner, the sterile sneutrino, can play a crucial role in early Universe cosmology as the dominant source of cold, warm, or hot dark matter, or of a subdominant relativistic population of sterile neutrinos that can contribute to the effective number of relativistic degrees of freedom Neff during big bang nucleosynthesis.

Entropy Growth in the Early Universe and Confirmation of Initial Big Bang Conditions

Science.gov (United States)

Beckwith, Andrew

2009-09-01

This paper shows how increased entropy values from an initially low big bang level can be measured experimentally by counting relic gravitons. Furthermore the physical mechanism of this entropy increase is explained via analogies with early-universe phase transitions. The role of Jack Ng's (2007, 2008a, 2008b) revised infinite quantum statistics in the physics of gravitational wave detection is acknowledged. Ng's infinite quantum statistics can be used to show that ΔS~ΔNgravitons is a startmg point to the increasing net universe cosmological entropy. Finally, in a nod to similarities AS ZPE analysis, it is important to note that the resulting ΔS~ΔNgravitons ≠ 1088, that in fact it is much lower, allowing for evaluating initial graviton production as an emergent field phenomena, which may be similar to how ZPE states can be used to extract energy from a vacuum if entropy is not maximized. The rapid increase in entropy so alluded to without near sudden increases to 1088 may be enough to allow successful modeling of relic graviton production for entropy in a manner similar to ZPE energy extraction from a vacuum state.

Modified holographic Ricci dark energy coupled to interacting dark matter and a non-interacting baryonic component

Energy Technology Data Exchange (ETDEWEB)

Chimento, Luis P.; Richarte, Martin G. [Universidad de Buenos Aires, IFIBA, CONICET, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina); Forte, Monica [Universidad de Buenos Aires, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina)

2013-01-15

We examine a Friedmann-Robertson-Walker universe filled with interacting dark matter, modified holographic Ricci dark energy (MHRDE), and a decoupled baryonic component. The estimations of the cosmic parameters with Hubble data lead to an age of the universe of 13.17 Gyr and show that the MHRDE is free from the cosmic-age problem at low redshift (0{<=}z{<=}2) in contrast to holographic Ricci dark energy (HRDE) case. We constrain the parameters with the Union2 data set and contrast with the Hubble data. We also study the behavior of dark energy at early times by taking into account the severe bounds found at recombination era and/or at big bang nucleosynthesis. The inclusion of a non-interacting baryonic matter forces that the amount of dark energy at z{sub t} {proportional_to} O(1) changes abruptly implying that {Omega} {sub x} (z {approx_equal}1100)=0.03, so the bounds reported by the forecast of Planck and CMBPol experiments are more favored for the MHRDE model than in the case of HRDE cutoff. For the former model, we also find that at high redshift the fraction of dark energy varies from 0.006 to 0.002, then the amount of {Omega} {sub x} at the big bang nucleosynthesis era does not disturb the observed helium abundance in the universe provided that the bound {Omega} {sub x} (z {approx_equal}10 {sup 10}) <0.21 is hold. (orig.)

Diffuse material, background radiation and the early universe

International Nuclear Information System (INIS)

Rees, M.J.

1980-01-01

Observations that relate to a qualitative picture of how galaxies formed, and what the Universe was really like at still earlier times, are presented. Some lines of evidence on the universe at redshifts out to z approximately equal to 5 are discussed, concentrating on the evidence which suggests that intergalactic medium has evolved in a 'multi phase' fashion. Some aspects of the less recent history of the Universe (i.e z approximately greater than 100) are considered, particularly the microwave background and the spectrum of inhomogeneities. (Auth.)