DOCSLIB.ORG

Challenges to the Standard Model of Big Bang Nucleosynthesis GARY STEIGMAN Departments of Physics and Astronomy, the Ohio State University, Columbus, OH 43210

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Challenges to the Standard Model of Big Bang Nucleosynthesis GARY STEIGMAN Departments of Physics and Astronomy, the Ohio State University, Columbus, OH 43210 Proc. Natl. Acad. Sci. USA Vol. 90, pp. 4779-4781, June 1993 Colloquium Paper This paper was presented at a colloquium entitled "Physical Cosmology," organized by a committee chaired by David N. Schramm, held March 27 and 28, 1992, at the National Academy of Sciences, Irvine, CA. Challenges to the standard model of Big Bang nucleosynthesis GARY STEIGMAN Departments of Physics and Astronomy, The Ohio State University, Columbus, OH 43210 ABSTRACT Big Bang nucleosynthesis provides a unique The gap at mass-5 ensured that 4He would be the second most probe of the early evolution of the Universe and a crucial test abundant element (after hydrogen) in the Universe and that of the consistency of the standard hot Big Bang cosmological any heavier elements would be produced only in trace model. Although the primordial abundances of 2H, 3He, 4He, amounts. Since 2H and 3He (as well as 3H) are being burned and 7Li inferred from current observational data are in agree- to 4He, the higher the nucleon abundance the more rapidly ment with those predicted by Big Bang nucleosynthesis, recent are 2H and 3He burned away and the smaller will be their relic analysis has severely restricted the consistent range for the abundance. The magnitude of the nucleon abundance [as nucleon-to-photon ratio: 3.7 s 110 ' 4.0. Increased accuracy measured by the universal ratio of nucleons to (cosmic in the estimate of primordial 4He and observations of Be and background radiation) photons: 1 N/ y; 710o 101°71] is B in Pop II stars are offering new challenges to the standard crucial also to bridging the gap at mass-5 and, therefore, the model and suggest that no new light particles may be allowed mass-7 abundance is sensitive to q1. As a result, the relic (NBBN < 3.0, where N,, is the number of equivalent light abundances of2H, 3He, and 7Li provide both upper and lower neutrinos). bounds to the universal abundance of nucleons (3), A hot dense genesis for the Universe is strongly suggested by 2H, 3He, 7Li: 2.8 -'-110 ' 4.0. [1] the presently observed expansion coupled with the thermal The cosmic background radiation temperature (Tyo = 2.74) at spectrum ofthe cosmic background radiation. Along with the present observed large-scale isotropy and homogeneity, these em- (7) permits us to infer the present density of nucleons pirical data form the basis of the "standard" (i.e., simplest) (in terms of the critical density), hot Big Bang cosmological model. Extrapolation to very QNh2 = [2a] early epochs within the context of this model point to the 0.0037'1lo infant Universe as a primordial nuclear reactor. It is the 0.010 < Nh20.015, [2b] comparison of the predicted abundances of those elements synthesized during the early evolution of the Universe with In Eq. 2, Q-N PN/PC, where PN is the nucleon density and Pc those inferred from current observational data that provides is the critical density and the Hubble parameter is Ho = lOOh one of the very few direct tests of the standard model as well km*s-l Mpc-1 [1 parsec (pc) = 3.09 x 1016 m] (or, H-l = as constraints on alternative cosmologies (1-3). At this sym- 9.8h-1 gigayears). This BBN bound on QkN may be compared posium, Pagel (4) and Schramm (5) have reviewed the current with various estimates of the current mass density thus status-and successes-of the standard model. The consist- connecting directly the early and present Universe. For h c ency between the predictions of standard Big Bang nucleo- 1, QIN ' 0.01, suggesting that some (perhaps most) nucleons synthesis (BBN) and the observational data not only lends in the Universe are "dark" (3). For a lower bound of Ho . support to the hot Big Bang model but also leads to con- 40 km'-s1-Mpc-1 (8), fQN 5 0.09, providing strong support for straints on the baryon density of the Universe (1-5) and on the possibility that the Universe is dominated by nonbaryonic particle physics beyond the standard model (6). matter. As impressive as the successes of the standard hot Big The relic abundance of4He is very sensitive to the balance Bang model are, eternal vigilance is a prerequisite for the between the universal expansion rate and the weak interac- success of any scientific enterprise. Any model worthy of tion rate, providing a sensitive probe of "new physics" (6). consideration is worthy of challenge. Here, I will comple- For an inferred primordial 4He mass fraction (4, 9), Yp < ment the contributions of Pagel (4) and Schramm (5) by 0.240, there is a very restrictive bound on light weakly examining those challenges to the consistency of (standard) interacting particles (3), BBN that seem most serious at present. As a potentially falsifiable model for the structure and evolution of the AN,= N,-3 '003, [3] Universe, the hot Big Bang cosmology should be the subject of constant scrutiny. where N, is the number of equivalent light neutrinos. If, indeed, the standard (homogeneous, isotropic, . .) hot The Standard Model Big Bang model provides an accurate description ofthe early evolution of the Universe, the inferred upper and lower Within the context of the standard model, when the Universe bounds to q should approach each other without crossing. was a few minutes old, conditions were right for nuclear Also, the LEP data (10) confirming the standard model result reactions to proceed rapidly, building the lightest nuclides that N -.3.0 [but, recall that LEP is sensitive to very massive (2H, 3He, 4He, and 7Li) (see refs. 1-5 and references therein). particles (sMz/2, where Mz is the Z-mass) that, if present, would play no role in BBN] leads to a lower bound to the The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" Abbreviation: BBN, Big Bang nucleosynthesis; ISM, interstellar in accordance with 18 U.S.C. §1734 solely to indicate this fact. gas. 4779 Downloaded by guest on September 26, 2021 4780 Colloquium Paper: Steigman Proc. Natl. Acad. Sci. USA 90 (1993) predicted primordial abundance of4He (3), Yp . 0.236, which With allowance for theoretical uncertainties, possible sys- must be tested. tematic observational uncertainties, and possible destruction of Li in these stars, Walker et al. (3) inferred (Li/H)p z 2 x Deuterium 10-10, which leads to the bounds on the nucleon abundance, Observations of 2H yield lower bounds to its primordial 7Li: 1.5 ' qlio s 4.0. [8] abundance (11) since 2H is destroyed in the course ofgalactic evolution. Very recent Hubble Space Telescope observa- Recently, a new wrinkle has been added to the quest for tions (12) of the local interstellar gas (ISM) toward Capella primordial Li. Be (16-18) and B (19) have been observed in yield several of the Spite plateau Pop II stars. The best (only) candidate for Be and B production in the early Galaxy is 105(2H/H)IsM = 1.65 - 0.07 [4] cosmic ray (spallation/fusion) nucleosynthesis (20-23). Along with any Be and B produced, 6'7Li will also be This is completely consistent with the earlier Copernicus synthesized by carbon, nitrogen, and oxygen (CNO) spalla- results summarized by Steigman (13) who found an average tion and, particularly, by a-a fusion (22). Although model- 105(2H/H)IsM = 1.6+ 30. It is of interest to compare this dependent uncertainties render very uncertain the prediction interstellar abundance with the presolar value (13). The 95% of absolute abundances of cosmic ray-produced Li, Be, and confidence level (2o-) ranges are B, relative abundances are less uncertain (22). Current Pop II Be and B data (16-19) are consistent with a cosmic ray origin 1.29 s 105(2H/H)IsM < 1.79 [5a] (22, 23) and suggest that perhaps -25% ofthe Li observed in the Spite plateau (15) stars may have a galactic (i.e., nonpri- and mordial) origin. Since there is a "floor" to BBN production of Li [(Li/H)BBN 2 1.1 x 10-10], it is crucial to attempt to 1.85 < 105(2H/H) C) < 3.27, [5b] separate the galactic and primordial contributions to the Li hinting at the possibility of some slight astration of 2H in the observed in Pop II stars. This could provide a crucial test of =4.6 gigayears since the formation of the solar system. the consistency of the standard hot Big Bang cosmology. Recently, Steigman and Tosi (14) have followed the evo- lution of 2H (and 3He) using models for the chemical evolu- Challenges tion of the Galaxy. In all models, there is little destruction of 2H between solar system formation and the present epoch Reanalysis of the 2H and 3He observations in the context of (less than a factor of 2.3), consistent with the results in Eq. models for the chemical evolution of the Galaxy (14) have 5. Steigman and Tosi (14) use solar system observations and narrowed the window ofconsistency. The inferred primordial their evolution models to set upper and lower bounds to abundances of 2H, 3He, and 7Li are still in concordance with primordial 2H, 3.9 s 105X2p < 9.0, which leads to constraints the predictions of standard BBN (3) but for a much more on the nucleon abundance, 3.4 ' q10 s 5.6, that are more restricted range ofnucleon abundance. Comparing Eqs. 6 and restrictive than previous constraints (3). Note, in particular 8, we have that the restrictive new upper bound to 2H [X2p < 9.0 x 10-5 2H, 3He, 7Li: 3.7 ' 7110 s 4.0.
Load more

Recommended publications
  • Near-Field Cosmology with Extremely Metal-Poor Stars
    AA53CH16-Frebel ARI 29 July 2015 12:54 Near-Field Cosmology with Extremely Metal-Poor Stars Anna Frebel1 and John E. Norris2 1Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139; email: [email protected] 2Research School of Astronomy & Astrophysics, The Australian National University, Mount Stromlo Observatory, Weston, Australian Capital Territory 2611, Australia; email: [email protected] Annu. Rev. Astron. Astrophys. 2015. 53:631–88 Keywords The Annual Review of Astronomy and Astrophysics is stellar abundances, stellar evolution, stellar populations, Population II, online at astro.annualreviews.org Galactic halo, metal-poor stars, carbon-enhanced metal-poor stars, dwarf This article’s doi: galaxies, Population III, first stars, galaxy formation, early Universe, 10.1146/annurev-astro-082214-122423 cosmology Copyright c 2015 by Annual Reviews. All rights reserved Abstract The oldest, most metal-poor stars in the Galactic halo and satellite dwarf galaxies present an opportunity to explore the chemical and physical condi- tions of the earliest star-forming environments in the Universe. We review Access provided by California Institute of Technology on 01/11/17. For personal use only. the fields of stellar archaeology and dwarf galaxy archaeology by examin- Annu. Rev. Astron. Astrophys. 2015.53:631-688. Downloaded from www.annualreviews.org ing the chemical abundance measurements of various elements in extremely metal-poor stars. Focus on the carbon-rich and carbon-normal halo star populations illustrates how these provide insight into the Population III star progenitors responsible for the first metal enrichment events. We extend the discussion to near-field cosmology, which is concerned with the forma- tion of the first stars and galaxies, and how metal-poor stars can be used to constrain these processes.
    [Show full text]
  • Initial Li Abundances in the Protogalaxy and Globular Clusters
    Draft version April 18, 2019 Typeset using LATEX preprint style in AASTeX62 Initial Li Abundances in the Protogalaxy and Globular Clusters Based upon the Chemical Separation and Hierarchical Structure Formation Motohiko Kusakabe1 and Masahiro Kawasaki2,3 1School of Physics, and International Research Center for Big-Bang Cosmology and Element Genesis, Beihang University, 37, Xueyuan Road, Haidian-qu, Beijing 100083, People’s Republic of China 2Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan 3Kavli IPMU (WPI), UTIAS, the University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8583, Japan (Received xxx, 2018; Revised xxx, 2018; Accepted xxx, 2018) ABSTRACT The chemical separation of Li+ ions induced by a magnetic field during the hierarchical structure formation can reduce initial Li abundances in cosmic structures. It is shown that cosmological reionization of neutral Li atoms quickly completes as soon as the first star is formed. Since almost all Li is singly ionized during the main course of structure formation, it can efficiently separate from gravitationally collapsing neutral gas. The separation is more efficient in smaller structures which formed earlier. In the framework of the hierarchical structure formation, extremely metal-poor stars can have smaller Li abundances because of their earlier formations. It is found that the chemical separation by a magnetic field thus provides a reason that Li abundances in extremely metal-poor stars are lower than the Spite plateau and have a large dispersion as well as an explanation of the Spite plateau itself. In addition, the chemical separation scenario can explain Li abundances in NGC 6397 which are higher than the Spite plateau.
    [Show full text]
  • The Metal-Poor End of the Spite Plateau I
    A&A 522, A26 (2010) Astronomy DOI: 10.1051/0004-6361/200913282 & c ESO 2010 Astrophysics The metal-poor end of the Spite plateau I. Stellar parameters, metallicities, and lithium abundances,, L. Sbordone1,2,3,P.Bonifacio1,2,4,E.Caffau2, H.-G. Ludwig1,2,5,N.T.Behara1,2,6, J. I. González Hernández1,2,7, M. Steffen8,R.Cayrel2,B.Freytag9, C. Van’t Veer2,P.Molaro4,B.Plez10, T. Sivarani11, M. Spite2, F. Spite2,T.C.Beers12, N. Christlieb5,P.François2, and V. Hill2,13 1 CIFIST Marie Curie Excellence Team, France 2 GEPI, Observatoire de Paris, CNRS, Université Paris Diderot, Place Jules Janssen, 92190 Meudon, France 3 Max-Planck Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching, Germany e-mail: [email protected] 4 INAF – Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, 34143 Trieste, Italy 5 Zentrum für Astronomie der Universität Heidelberg, Landessternwarte, Königstuhl 12, 69117 Heidelberg, Germany 6 Institut d’Astronomie et d’Astrophysique, Université Libre de Bruxelles, CP 226, boulevard du Triomphe, 1050 Bruxelles, Belgium 7 Dpto. de Astrofísica y Ciencias de la Atmósfera, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain 8 Astrophysikalisches Institut Potsdam An der Sternwarte 16, 14482 Potsdam, Germany 9 Centre de Recherche Astrophysique de Lyon, UMR 5574: Université de Lyon, École Normale Supérieure de Lyon, 46 allée d’Italie, 69364 Lyon Cedex 07, France 10 Université Montpellier 2, CNRS, GRAAL, 34095 Montpellier, France 11 Indian Institute of Astrophysiscs, II Block, Koramangala, Bangalore 560 034, India 12 Dept. if Physics & Astronomy, and JINA: Joint Insrtitute for Nuclear Astrophysics, Michigan State University, E.
    [Show full text]
  • Cosmological Lithium Problems
    EPJ Web of Conferences 184, 01002 (2018) https://doi.org/10.1051/epjconf/201818401002 9th European Summer School on Experimental Nuclear Astrophysics Cosmological Lithium Problems C.A. Bertulani1,�, Shubhchintak1,��, and A.M. Mukhamedzhanov2,��� 1Department of Physics and Astronomy, Texas A&M University-Commerce, Commerce, TX 75429, USA 2Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843, USA Abstract. We briefly describe the cosmological lithium problems followed by a summary of our recent theoretical work on the magnitude of the effects of electron screening, the possible existence of dark matter parallel universes and the use of non-extensive (Tsal- lis) statistics during big bang nucleosynthesis. Solutions within nuclear physics are also discussed and recent measurements of cross-sections based on indirect experimental tech- niques are summarized. 1 Introduction The cosmological lithium problem has become one of the most intriguing open questions in cos- mology due to inconsistencies between observation and calculations based on the standard Big Bang nucleosynthesis (BBN) for the primordial elemental abundances. The BBN model contains a few parameters such as the baryon-to-photon ratio η = nb/nγ, the neutron decay time τn, and the number of neutrino families Nν (see, for instance, Ref. [1]). The parameter η relates to the baryon density of the universe by means of Ω h2 (η/10 10)/273, with the Hubble dimensionless parameter h defined 0 � − through the relation H0 = 100h km/s/Mpc, the index ‘0’ meaning present time. The anisotropies of the cosmic microwave radiation (CMB) independently determine the value of η [2, 3] when the uni- verse was about 0.3 Myr after the Big Bang.
    [Show full text]
  • Evolution of Low Mass Stars: Lithium Problem and -Enhanced Tracks and Isochrones
    SISSA - International School for Advanced Studies Evolution of low mass stars: lithium problem and α-enhanced tracks and isochrones Dissertation Submitted for the Degree of “Doctor Philosophiæ” Supervisors Candidate arXiv:1702.02932v1 [astro-ph.SR] 9 Feb 2017 Prof. Alessandro Bressan Xiaoting FU Dr. Paolo Molaro Dr. Leo´ Girardi October 2016 ii We are the dust of stars. Contents Abstract iii Acronyms v 1 Introduction 1 1.1 Historic progress in understanding stars .............. 1 1.2 Modern stellar evolution models .................. 4 1.2.1 Equations of stellar structure and evolution ........ 5 1.2.2 Boundary conditions .................... 7 1.2.3 Opacity ........................... 8 1.2.4 PARSEC (PAdova and TRieste Stellar Evolution Code) .. 11 1.2.5 Other stellar models .................... 12 1.3 Solar-scaled mixture and α enhancement .............. 15 1.4 Lithium in stars, origin and problems ................ 16 1.4.1 Cosmological lithium problem ............... 17 I PARSEC tracks and isochrones with α enhancement 23 2 Input physics 27 2.1 Nuclear reaction rates ........................ 27 2.2 Equations of state .......................... 29 2.3 Solar model ............................. 30 2.4 α enhancement ........................... 34 2.5 Helium content ........................... 35 3 Calibration with 47Tuc 37 3.1 Metal mixtures ........................... 38 3.2 Isochrones fitting and Luminosity function ............. 47 3.2.1 Low main sequence to turn-off ............... 47 3.2.2 RGB bump and envelope overshooting calibration .... 49 i ii CONTENTS 3.2.3 Red Giant Branch ...................... 57 3.2.4 Horizontal Branch morphology .............. 66 4 RGB bump comparison with other GC data and models 79 4.1 Comparison with other models ................... 79 4.2 Comparison with other GC data .................
    [Show full text]
  • Lithium in Very Metal-Poor Dwarf Stars - Problems for Standard Big Bang Nucleosynthesis?
    Lithium in Very Metal-poor Dwarf Stars - Problems for Standard Big Bang Nucleosynthesis? David L. Lambert The W.J. McDonald Observatory, University of Texas, Austin, Texas, USA Abstract. The standard model of primordial nucleosynthesis by the Big Bang as selected by the WMAP-based estimate of 2 7 the baryon density (Ωbh ) predicts an abundance of Li 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 6 7 of Li (and Li) 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. INTRODUCTION Observers and theoreticians have long regarded Big Bang nucleosynthesis as providing a simple testable set of reliable predictions with one free parameter to be determined by observations of the primordial relative abundances of the 1 2 3 4 7 2 light nuclides H, H, He, He, and Li. That free parameter is the baryonic density Ωbh or, equivalently, the number 2 7 1 ¢ density ratio of baryons to photons η: Ω bh 3 652 10 η where h is the Hubble constant in units of 100 km s Mpc 1.
    [Show full text]
  • Arxiv:2011.02659V2 [Astro-Ph.GA] 4 Jul 2021 Samples of Halo and Disk Stars
    MNRAS 000,1–12 (2021) Preprint 6th July 2021 Compiled using MNRAS LATEX style file v3.0 The GALAH Survey: Accreted stars also inhabit the Spite Plateau Jeffrey D. Simpson,1,2¢ Sarah L. Martell,1,2 Sven Buder,2,3 Joss Bland-Hawthorn,2,4 Andrew R. Casey,5,6 Gayandhi M. De Silva,7,8 Valentina D’Orazi,9 Ken C. Freeman,2,3 Michael Hayden,2,4 Janez Kos,10 Geraint F. Lewis,4 Karin Lind,11 Katharine J. Schlesinger,3 Sanjib Sharma,2,4 Dennis Stello,1,2,4 Daniel B. Zucker,2,8,12 Tomaž Zwitter,10 Martin Asplund,13 Gary Da Costa,2,3 Klemen Čotar,10 Thor Tepper-García,2,4,14 Jonathan Horner,15 Thomas Nordlander,2,3 Yuan-Sen Ting,3,16,17,18 Rosemary F. G. Wyse19 and The GALAH Collaboration 1School of Physics, UNSW, Sydney, NSW 2052, Australia 2Centre of Excellence for Astrophysics in Three Dimensions (ASTRO-3D), Australia 3Research School of Astronomy & Astrophysics, Australian National University, ACT 2611, Australia 4Sydney Institute for Astronomy, School of Physics, A28, The University of Sydney, NSW, 2006, Australia 5School of Physics and Astronomy, Monash University, Clayton, VIC 3800, Australia 6Monash Centre for Astrophysics, School of Physics and Astronomy, Monash University, Australia 7Australian Astronomical Optics, Faculty of Science and Engineering, Macquarie University, Macquarie Park, NSW 2113, Australia 8Macquarie University Research Centre for Astronomy, Astrophysics & Astrophotonics, Sydney, NSW 2109, Australia 9Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova, vicolo dell’Osservatorio 5, 35122, Padova, Italy 10Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia 11Department of Astronomy, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm, Sweden 12Department of Physics and Astronomy, Macquarie University, Sydney, NSW 2109, Australia 13Max Planck Institute for Astrophysics, Karl-Schwarzschild-Str.
    [Show full text]
  • The Cosmological Lithium Problem Outside the Galaxy: the Sagittarius Globular Cluster M54 !
    Mon. Not. R. Astron. Soc. 000,000–000(0000) Printed28July2014 (MNLaTEXstylefilev2.2) The cosmological Lithium problem outside the Galaxy: the Sagittarius globular cluster M54 ! A. Mucciarelli,1 M. Salaris,2,P.Bonifacio3,L.Monaco4 and S. Villanova5 1Dipartimento di Fisica & Astronomia, Universit`adegliStudidiBologna,VialeBertiPichat,6/2-40127,Bologna,Italy 2Astrophysics Research Institute, Liverpool John Moores University, IC2, 146 Brownlow Hill, Liverpool L3 5RF, United Kingdom 3GEPI, Observatoire de Paris, CNRS, Univ. Paris Diderot, 92125, Meudon Cedex, France 4European Southern Observatory, Casilla 19001, Santiago, Chile 5Universidad de Concepcion, Casilla 160-C, Concepcion, Chile 28 July 2014 ABSTRACT The cosmological Li problem is the observed discrepancy between Li abundance (A(Li)) measured in Galactic dwarf, old and metal-poor stars (traditionally assumed to be equal to the initial value A(Li)0), and that predicted by standard Big Bang Nucleosynthesis calculations (A(Li)BBN ). Here we attack the Li problem by consid- ering an alternative diagnostic, namely the surface Li abundance of red giant branch stars that in a colour magnitude diagram populate the region between the completion of the first dredge-up and the red giant branch bump. We obtained high-resolution spectra with the FLAMES facility at the Very Large Telescope for a sample of red giants in the globular cluster M54, belonging to the Sagittarius dwarf galaxy. We ob- tain A(Li)= 0.93 0.11 dex, translating – after taking into account the dilution due ± to the dredge up– to initial abundances (A(Li)0) in the range 2.35–2.29 dex, depend- ing on whether or not atomic diffusion is considered.
    [Show full text]
  • Cosmological Implications of Light Element Abundances: Theory DAVID N
    Proc. Natl. Acad. Sci. USA Vol. 90, pp. 4782-4788, June 1993 Colloquium Paper This paper was presented at a colloquium entitled "Physical Cosmology," organized by a committee chaired by David N. Schramm, held March 27 and 28, 1992, at the National Academy of Sciences, Irvine, CA. Cosmological implications of light element abundances: Theory DAVID N. SCHRAMM Astronomy and Astrophysics Centers 140, The University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637; and National Aeronautic and Space Administration/Fermilab Astrophysics Center, Fermi National Accelerator Laboratory, Box 500, Batavia, IL 60510-0500 ABSTRACT Primordial nucleosynthesis provides (with number of neutrino families and its subsequent verification the microwave background radiation) one of the two quanti- by the Large Electron Positron Collider (LEP) and the tative experimental tests of the hot Big Bang cosmological Stanford Linear Collider (SLC). model (versus alternative explanations for the observed Hubble Also discussed is the possibility that a first-order quark- expansion). The standard homogeneous-isotropic calculation hadron phase transition could have produced variations from fits the light element abundances ranging from 'H at 76% and the standard homogeneous model. It will be shown that 4He at 24% by mass through 2H and 3He at parts in 105 down contrary to initial indications, first-order quark-hadron- to 7Li at parts in 1010. It is also noted how the recent Large inspired results are consistent with the homogeneous model Electron Positron Collider (and Stanford Linear Collider) results. results on the number of neutrinos (N,,) are a positive labora- Finally, a discussion of the recent B and Be observations tory test of this standard Big Bang scenario.
    [Show full text]
  • Exploring the Origin of Lithium, Carbon, Strontium, and Barium with Four New Ultra Metal-Poor Stars
    EXPLORING THE ORIGIN OF LITHIUM, CARBON, STRONTIUM, AND BARIUM WITH FOUR NEW ULTRA METAL-POOR STARS The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Hansen, T., C. J. Hansen, N. Christlieb, D. Yong, M. S. Bessell, A. E. Garcia Perez, T. C. Beers, et al. “EXPLORING THE ORIGIN OF LITHIUM, CARBON, STRONTIUM, AND BARIUM WITH FOUR NEW ULTRA METAL-POOR STARS.” The Astrophysical Journal 787, no. 2 (June 1, 2014): 162. © 2014 The American Astronomical Society As Published http://dx.doi.org/10.1088/0004-637X/787/2/162 Publisher IOP Publishing Version Final published version Citable link http://hdl.handle.net/1721.1/94583 Terms of Use Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The Astrophysical Journal, 787:162 (9pp), 2014 June 1 doi:10.1088/0004-637X/787/2/162 C 2014. The American Astronomical Society. All rights reserved. Printed in the U.S.A. EXPLORING THE ORIGIN OF LITHIUM, CARBON, STRONTIUM, AND BARIUM WITH FOUR NEW ULTRA METAL-POOR STARS∗ T. Hansen1,C.J.Hansen1, N. Christlieb1,D.Yong2,M.S.Bessell2,A.E.Garc´ıa Perez´ 3, T. C. Beers4,5, V. M. Placco6, A. Frebel7, J. E. Norris2, and M. Asplund2 1 Landessternwarte, ZAH, Konigstuhl¨ 12, D-69117 Heidelberg, Germany; [email protected], [email protected], [email protected] 2 Research School of Astronomy and Astrophysics, The Australian National University, Weston,
    [Show full text]
  • Protostellar Accretion in Low Mass Metal Poor Stars and the Cosmological Lithium Problem
    Astronomy & Astrophysics manuscript no. Tognelli_AccAndLithium_CorrectedLang c ESO 2020 May 1, 2020 Protostellar accretion in low mass metal poor stars and the cosmological lithium problem Emanuele Tognelli1, Pier Giorgio Prada Moroni1; 2, Scilla Degl’Innocenti1; 2, Maurizio Salaris3, and Santi Cassisi2; 4 1 Dipartimento di Fisica, Università di Pisa, Largo Bruno Pontecorvo 3, I-56127, Pisa, Italy e-mail: [email protected] 2 INFN - Sezione di Pisa, Largo Bruno Pontecorvo 3, I-56127, Pisa, Italy e-mail: [email protected] e-mail: [email protected] 3 Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, UK 4 INAF - Osservatorio Astronomico d’Abruzzo, Via M. Maggini, I-64100, Teramo, Italy Received 18 September, 2019; accepted 24 April, 2020 ABSTRACT Context. The cosmological lithium problem, that is, the discrepancy between the lithium abundance predicted by the Big Bang nucleosynthesis and the one observed for the stars of the ’Spite plateau’, is one of the long standing problems of modern astrophysics. Recent hints for a possible solution involve lithium burning induced by protostellar mass accretion on Spite plateau stars. However, to date, most of the protostellar and pre-main sequence stellar models that take mass accretion into account have been computed at solar metallicity, and a detailed analysis on the impact of protostellar accretion on the lithium evolution in the metal-poor regime, which is relevant for stars in the Spite plateau, is completely missing. Aims. The purpose of this paper is to fill this gap, analysing, in detail, for the first time the effect of protostellar accretion on low metallicity low-mass stars with a focus on pre-main sequence lithium evolution.
    [Show full text]
  • The Evolution of Lithium: Implications of a Universal Spite Plateau
    MNRAS 000,1–7 (2021) Preprint 26 April 2021 Compiled using MNRAS LATEX style file v3.0 The evolution of Lithium: implications of a universal Spite plateau Francesca Matteucci,1,2,3¢ Marta Molero,1 David S. Aguado4 and Donatella Romano5 1Department of Physics, University of Trieste, Italy 2Italian National Institute for Astrophysics (I.N.A.F.) Trieste, Italy 3Italian National Institute for Nuclear Physics (I.N.F.N.), Trieste, Italy 4Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK 5Italian National Institute for Astrophysics (I.N.A.F.) Bologna, Italy Accepted XXX. Received YYY; in original form ZZZ ABSTRACT The cosmological 7Li problem consists in explaining why the primordial Li abundance, as predicted by the standard Big Bang nucleosynthesis theory with constraints from WMAP and Planck, is a factor of 3 larger than the Li abundance measured in the stars of the Spite plateau defined by old, warm dwarf stars of the Milky Way halo. Several explanations have been proposed to explain this difference, including various Li depletion processes as well as non standard Big Bang nucleosynthesis, but the main question remains unanswered. In this paper, we present detailed chemical evolution models for dwarf spheroidal and ultra faint galaxies, compute the galactic evolution of 7Li abundance in these objects and compare it with observations of similar objects. In our models, Li is mainly produced by novae and cosmic rays and to a minor extent by low and intermediate mass stars. We adopt the yield combination which best fits the Li abundances in the Milky Way stars.
    [Show full text]