Primordial Nucleosynthesis Standard Big-Bang Nucleosynthesis of 4 He, D, 3 He, 7 Li compared with observations The SBBN “lithium problem”: nuclear aspects ( 6 Li, 9 Be , 10,11 B) and CNO in extended SBBN network Conclusions Alain Coc (Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, Orsay)
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Primordial Nucleosynthesis Standard Big-Bang Nucleosynthesis of 4 He, D, 3 He, 7 Li compared with observations The SBBN “lithium problem”: nuclear.
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Primordial Nucleosynthesis
Standard Big-Bang Nucleosynthesis of 4He, D, 3He, 7Li compared with observations
The SBBN “lithium problem”: nuclear aspects
(6Li, 9Be , 10,11B) and CNO in extended SBBN network
Conclusions
Alain Coc (Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, Orsay)
Three observational evidences for the Big-Bang Model
1. The expansion of the Universe
2. The Cosmic Microwave Background radiation (CMB)
3. Primordial nucleosynthesis
Reproduces the light-elements 4He, D, 3He, 7Li primordial abundances over a range of nine orders of magnitudes.
First determination of the baryonic density of the Universe, (1-3)×10-31g/cm3 [Wagoner 1973], need for baryonic dark matter
First determination of the number of light neutrino families, Nν ≤ 3 [Yang, Schramm, Steigman, Rood 1973]
Number of neutrino families Nν = 2.984±0.008 [LEP experiments]
Determination of the baryonic density of the Universe
Baryonic density B ≈ 4.5×10-31g/cm3 from the anisotropies in the Cosmic Microwave Background radiation, ...., WMAP, Planck (2014?)
bh2=0.022490.00057 =(6.160.16)×10-10
[WMAP: Komatsu et al. (2011)]
/C with C the critical density The number of baryons per photon, nb/n and bh2= 3.65107
BBN: a probe of physics of the early Universe
Why BBN after WMAP?Key questions in Cosmology: Nature of dark matter Nature of dark energy Gravitation = General Relativity ? Variation of constants
G→G(1+α2(t))
[Coc, Olive, Uzan & Vangioni 2009]
(Tensor-Scalar gravity)
The 12 reactions of standard BBN
Standard BBN No convection No diffusion No mixing Known physics <12 reactions
Simple nucleosynthesis (?)
⇒
10 thermonuclear reaction rates deduced from experimental data
The neutron lifetime is still a matter of debate (but not essential to BBN)
n = 885.70.8 s [PDG 2008] or n=878.50.7 0.3 s [Serebrov et al. 2005] 881.5 ± 1.5 s [PDG 2011] ; 880–884 s [Wietfeldt & Greene 2011]
np ∝ n-1
å (phase space)(e distribution)(e distribution) dE
+ small corrections
• Weak rate change mostly affects n/p ratio at freeze out and hence 4He abundance• Change in expansion rate gives similar effect (n/p freezeout when weak rate
expansion rate)
1H(n,)D : theory versus experiments
Rate calculated from Effective Field theory with (theoretical) uncertainties of 4% [Chen & Savage (1999)] or 1% [Rupak (2000)] compared to experiments [Arenhovel & Sanzone (1991) review]
BBN energy ~ 25 keV
Additional check with polarized beam E1 and M1measurements [Tornow et al. (2000)], e-scattering [Ryezaveva et al. 2006] and new (>1991) cross section measurements [Suzuki et al. (1995), Tomyo et al. (2003)]
Chen & Savage (1999)
Boltzmann
10 rates deduced from experimental data
Compilations and evaluations for/including BBN thermonuclear rates
Smith, Kawano & Malaney 1999 (with uncertainties)
NACRE, Angulo et al. 1999 (7/10, tabulated rates and uncertainties)
Nollett & Burles 2000 (no rates provided)
Cyburt, Fields & Olive 2003 (revaluation of NACRE)
Serpico et al. 2004 (rates and uncertainties provided)
keV.b (13% higher than in DAACV04) S(0) = 0.56±0.02±0.02 keV.b [Adelberger et al. 2010]
Determination of primordial abundances
Primordial abundances :
1) Observe a set of primitive objects born when the Universe was young
2) Extrapolate to zero “metallicity” (the heavy elements whose abundance increase with time) e.g. Fe/H, O/H, Si/H,…. 0• 4He in H II (ionized H) regions of blue compact galaxies:
0.245 < Yp < 0.262 [Aver, Olive & Skillman 2011]
• D in remote cosmological clouds (i.e. at high redshift) on the line of sight of quasars: (2.84±0.26)× 10-5 (1-) [Fields & Sarkar 2008]
• 3He in H II regions of our Galaxy: 3He/H ≤ (1.1±0.2)×10-5 [Bania et al. 2002]
• 7Li at the surface of low metallicity stars in the halo of our Galaxy: Li/H = (1.58±0.31)10-10 [Sbordone et al. 2010]
[Izotov, Thuan & Stasinska 2007]
Burles & Tytler 1998a,b; O’Meara et al. 2001; D’Odorico et al. 2001; Pettini & Bowen 2001; Kirkman
et al. 2003, Crighton et al. 2004, Pettini et al. 2008, Fumagalli et al. 2011, Srianand et al. 2010, Cooke et al.
• No resonance observed at Oak Ridge in D(7Be,d)7Be scattering [O’Malley et al. 2011]
• Measured Ex=16.8 MeV and =81 keV [Scholl et al. 2011] primordial effect on ⇒ 7Li < 4% [Kirsebom & Davids 2011]
The 7Be(n,)4He reaction [M. Gai priv. comm.]• If l=0, 7Be+n→2 (forbiden) rate from Wagoner 1969 • If l=1, could contribute to 7Be destruction [Serpico et al. 2004]• Experimental project with n beam from Liquid Lithium Target
(LiLiT) at the Soreq Accelerator Facility (SARAF) [M. Gai priv. comm.]
• No new 10C level• Broad levels?• Unlikely to contribute
(Coulomb barrier) [Broggini et al. ArXiv:1202.523]
In search of new 10C levels: 10B(3He,t)10C
BBN extended network up to CNO
Applications of extended network:
• CNO seeds for first stars : CNO/H > 10-11 [Cassisi & Castellani 1993] : CNO/H > 10-13 [Ekström et al. 2008]
• Potential neutron sources for 7Be destruction by 7Be(n,p)7Li(p,)4He in BBN (the lithium problem)? Unexpected effect (e.g. 7Li sensitivity to n(p,γ)d)
• Standard CNO primordial abundances versus exotic production (e.g. “variation of fundamental constants”)
Extended network predictions : CNO/H ≈ 10-15 [Iocco et al. 2007] but reaction rates not given
CNO nucleosynthesis updated network
Z A
n 1
H 1-3
He 3,4,6
Li 6-9
Be 7,9-12
B 8,10-15
C 9-16
N 12-17
O 13-20
F 17-20
Ne 18-23
Na 20-23
59 isotopes : 391 reaction rates AZ + n, p, d, t, 3He and , mostly unknown hence possibly high yield uncertainty Descouvemont et al. 2004 (DAACV)
Angulo et al. 1999 (NACRE I)
Iliadis et al. 2010
Talys (271 rates) within 3 orders of magnitude, at T≈1 GK, compared with experiments!