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Nucleosynthèse Primordiale : bilan et perspectives

Nucleosynthèse Primordiale : bilan et perspectives. Alain Coc ( C entre de S pectrométrie N ucléaire et de S pectrométrie de M asse, Orsay) Elisabeth Vangioni ( I nstitut d’ A strophysique de P aris ). Introduction Standard Big-Bang Nucleosynthesis  B determination Observations

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Nucleosynthèse Primordiale : bilan et perspectives

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  1. Nucleosynthèse Primordiale : bilan et perspectives Alain Coc (Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, Orsay) Elisabeth Vangioni (Institut d’Astrophysique de Paris ) • Introduction • Standard Big-Bang Nucleosynthesis • B determination • Observations • Nuclear data • Concordance BBN/CMB/Spectroscopy • Beyond the Standard Big-Bang model

  2. Determination of the baryonic density of the Universe • Standard Big Bang Nucleosynthesis Calculated and observed 4He, D,3He,7Li primordial abundances   (orBh2) Need good: • Observational data • Nuclear data • Anisotropies in the Cosmic Microwave Background radiation BOOMERanG, CBI, DASI, MAXIMA, ARCHEOPS, WMAP,…..

  3. Density components of the Universe A natural reference : the critical density = 1.88 h2  10-29 g/cm3 or2.9 h2  1011 M/Mpc3 (h=H0/100 km/s/Mpch0.7) /C Number of baryons per photon :  nb/net bh2= 3.65107 

  4. Anisotropies of the Cosmic Microwave Background (CMB) • Geometry (T1), 1st peak • b (2nd/1st peaks) Spatial fluctuation spectrum of CMB  (Inertia from baryons) bh2=0.02240.0009 =(6.1340.246)×10-10[WMAP: Spergel et al. (2003)]

  5. Isotopes to constrain  : 4He : little sensitive to  3He : complex stellar production / destruction history. D : seems the best candidate: a strong monotonic evolution with  and no stellar production. 7Li : main drawback: a non monotonic evolution with ; two  values for a given Li/H

  6. Nucleosynthesis (I) Equilibrium as long as the reaction rate is faster than the expansion rate: Followed by decoupling and freezeout Equilibriumpn: Nn/Np=exp(-mnp/kT) ; mnp= 1.29 MeV Equilibrium breaks out when : ThenT 1010 Kand Nn/Np 0.2

  7. Nucleosynthesis (II) Neutrons decay until T is low enoughfor : n+pD+ becomes faster then deuterium photodisintegration D+  n+p (Q = -2.2 MeV) Then,t = 3 mn, T 109 Kand Nnhas decrased toNn/Np 0.1 Nucleosynthesis starts to produce essentially4Hetogether with traces ofD, 3He, 7Li, …. X(4He)  2X(n)  0.2

  8. [Burles & Tytler 1998] Observations (I) : D Lyman- forest Cloud at redshift of z = 3.6 on the line of sight of quasar QSO 1937-1009 • Observations : • D/H ratio at high redshift from the depth/width of absorption lines • Baryonic density (b) from the census of the « Lyman- Forest » lines D

  9. (2.78+0.44-0.38)× 10-5[Kirkman et al. 2003] Protosolar 2002 2003 Local ISM 10-5 [X/H]= log10( (X/H) / (X/ H) ) [X/H]= log10( (X/H) / (X/ H) ) D/H observations in cosmological clouds Burles & Tytler 1998a,b;O’Meara et al. 2001; D’Odorico et al. 2001; Pettini & Bowen 2001; Kirkman et al. 2003

  10. Observation (II) : Li abundances in low metallicity stars • Spite plateau: Li/H versus metallicity (time) Li/H1.12 10-10 [Spite & Spite, 1982]; • (0.91-1.91)10-10 (95% c.l.) [Ryan et al. 2000]; • 2.3410-10 [Meléndez & Ramirez 2004]; • (1.1-1.5)10-10 [Asplund et al. 2005] • Low dispersion • 6Li observed  In principle, low Li destruction  0.1 dex • Reliable primordial abundance (in principle)

  11. Observations (III) : 4He • 4He from a sample of 82 H II regions in 76 blue compact galaxies: • Yp= 0.2421±0.0021 • [Izotov & Thuan 2003] • From a selected sub-sample • 0.232 < Yp < 0.258 • [Olive & Skillman 2004] • Previously used values : • Yp=0.2452±0.0015[Izotov et al. (1999)] • Yp=0.2391±0.0020[Peimbert et al. (2002)]

  12. Observations (IV) : 3He 3He/H data [Bania et al. 2002] but at high metallicity : weak constrains on primordial value [Vangioni-Flam et al. 2002]. 3He Calculated (BBN+CMB) 3He/H=1.010-5 No 3He evolution since BBN 3He/H = (1.1±0.2)×10-5 Li

  13. The 12 reactions of standard BBN • Origin of reaction rates • Theoretical: • np : with n=885.70.8 s [PDG 2004](n=878.50.7 0.3 [Serebrov et al. 2005, Mathews, Kajino & Shima 2004]), otherwise small uncertainty [Brown & Sawyer (2001)] • 1H(n,)2H : Two nucleons effective field theory [Chen & Savage (1999)] • Experimental : • New compilation [Descouvemont, Adahchour, Angulo, Coc & Vangioni-Flam (2004)]

  14. Nuclear reaction rates analysis • « R-Matrix » formalism: S-factors fits of data constrained by theory • Reaction rates measured at BBN energies [Descouvemont, Adahchour, Angulo, Coc & Vangioni-Flam ADNDT (2004)]

  15. Comparison between observed and calculated abundances Limits (1-) obtained by Monte-Carlo from DAACVreaction rate uncertainties [Coc, Vangioni-Flam,Descouvemont, Adahchour, Angulo, ApJ (2004)] 2-3 factor !

  16. 6Li observations in halo stars Nissen et al. (1999); Cayrel, et al. (1999); Aoki et al. (2004); Asplund et al. (2005) Observed ratio in halo stars :6Li/7Li  0.05 Calculated ratio (BBN+CMB) :6Li/7Li ~10-4-5

  17. The Li problems Descouvemont et al.; Coc et al. (2004) 7Be(d,p)2  100 Ryan et al. (2000) Uncertainty from 2H(,)6Li (NACRE) 4He(t,n)6Li, 7Li(p,d)6Li : Q ≈ -5MeV

  18. 200 g/cm2 CD2 target 7Be beam p 40 cm The 7Be(d,p)2 experiment Centre de Recherche du Cyclotron, Louvain-la-Neuve One multi-strips LEDA detector ECR source at CRC Beam : 0.2-1. 107 pps of 7Be at 5.8 MeV, degraded to 1.8 MeV (0.4 MeV c.m.) Target :200 g/cm2 CD2 poliethylene Detectors : two (LEDA) multistrips (816) Si detectors (300 and 500 m) LEDA 1 & 2

  19. 9B ground state and first excited level contribution (comparison with Kavanagh) • All 9B level contribution • No cross section enhancement • No nuclear solution to the 7Li problem 7Be(d,p)2 cross-section Integrated (ΔE0.23 MeV) cross section[Angulo et al. , ApJL (2005) ] Experiment at Louvain-la-Neuve

  20. Experimental data on D(,)6Li reaction • At BBN energies only Coulomb Dissociation data : • Kiener et al. (1991) differs from theoretical extrapolations • At BBN energies only Coulomb Dissociation data : • Kiener et al. (1991) differs from theoretical extrapolations • Hammache et al. (2005) agrees! Also with direct data Experiment at GSI (provisional)

  21. The Li problems unsolved by nuclear physics • 7Be(d,p)2 : effect negligible • D(,)2 : too low • R-matrix analysis of D(,)2 data to be done • 6Li/H710-15 (±40%) (D(,)2, 6Li(p,), Bh2) • Other solutions (?) • Stellar depletion (7Li), observational bias, heavy particle decay, proto/ pregalactic production (6Li), ……

  22. Origin of CMB, SBBN and Li observations discrepancies • Nuclear : No! • Stellar (7Li) ? • Observational bias: 1D/3D, LTE/NLTE model atmospheres, effective temperature scale • Li stellar destruction (but low dispersion!) • Non Standard Model(s) ? • Affecting expansion rate during BBN : Quintessence, Tensor-Scalar gravity, ν-degeneracy,…. • Variation of fundamental couplings : em[Ichikawa & Kawasaki 2004], or all[Landau et al. 2005] • Massive particle decay: can destroy 7Li but 3He/D problem [Jedamzik (2004), Kawasaki et al. (2005), Ellis et al. (2005)] • Pregalactic/protogalactic 6Li production [Suzuki & Inoue (2002); Rollinde et al. 2005] (poster Rollinde et al.)

  23. Influence of the expansion rate Abundances as a function of the “effective number of neutrino families”: a parametrisation of the expansion rate.

  24. Neutrino degeneracy • But difference in ξνsmeared out by neutrino oscillations

  25. Basics of Scalar Tensor theories of Gravitation Most general theories of gravity include a scalar field beside the metric Mathematically consistent Motivated by superstring dilaton in the graviton supermultiplet, modulii after dimensional reduction Only consistent massless field theory to satisfy Weak Equivalence Principle Preserve most symmetries of general relativity Useful extension of GR (simple but general enough) spin 2 spin 0

  26. Basics of Scalar Tensor theories of Gravitation If the coupling (A()) has a minimum, it is attracted toward GR Damour, Nordtvedt, PRL 70 (1993) 2217 Such solutions are argued to be ``natural ’’ in string theory Damour, Polyakov, NPB 423 (1994) 532 • Constrains atz=0 (present),z=103(CMB) andz~108 (BBN) [following Damour & Pichon PRD 1999] • Test of BBN code with TS gravity including a potential

  27. Evolution of the scalar component from z=1011 until now a(φ) = ½βφ2 = ln(A(φ)) Now CMB BBN [Coc, Olive, Uzan, Vangioni, PRD to be submitted]

  28. BBN constraints on Scalar Tensor theories of Gravitation 7Li 4He [Coc, Olive, Uzan, Vangioni, PRD to be submitted]

  29. Collaborations Théories Tenso-Scalaires de la gravitation, …… Jean-Philippe Uzan (IAP) Keith Olive (University of Minnesota) Observations (6Li) R. Cayrel(IAP) F. Spite & M. Spite (Observatoire de Paris-Meudon) Physique nucléaire expérimentale Carmen Angulo(CRC,UcL, Louvain la Neuve) Faïrouz Hammache (IPNO) Physique nucléaire théorique Pierre Descouvemont(Université Libre de Bruxelles) Physique des neutrinos Cristina Volpe (IPNO)

  30. Conclusions et perspectives • SBBN calculations with nuclear reaction rates under control • Confirms good agreement for B values deduced from : • CMB, • SBBN (D and 4He), • However disagreement between Li observations, SBBN and CMB : • Nuclear : no! • Stellar, cosmology, origin ? • New 6Li observations in halo stars : 6Li/ 7Li  0.05 • New observations planned at VLT • BBN is now a parameter free model ! • Test of theories beyond the Standard Model • TS theories of gravity • Neutrino properties • …….

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