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Richard H. Cyburt Heavy Element Nucleosynthesis s-process r-process p-process NSE Iron Group Hydro Static Nucl.

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Presentation on theme: "Richard H. Cyburt Heavy Element Nucleosynthesis s-process r-process p-process NSE Iron Group Hydro Static Nucl."— Presentation transcript:

1 Richard H. Cyburt

2 Heavy Element Nucleosynthesis s-process r-process p-process NSE Iron Group Hydro Static Nucl.

3  If universe ~14 Gyr old ◦ Where’d we get so much H & He???  pp-chain is too slow  massive stars burn beyond He ◦ Stars must have been born with that H & He  Big bang nucleosynthesis

4  What building blocks are available? ◦ n, p, nuclides, e, g, n, etc…  What are the reaction time scales? ◦ Related to rxn rates: t = 1/ G  What are the dynamical time scales? ◦ Hydro-static EQ; no time scale ◦ Free-fall time t = finite

5 First published in Weltall and Menschheit (1907) edited by Hans Kraemer

6  Cosmological Principle ◦ Universe is homogeneous  looks the same anywhere we go ◦ Universe is isotropic  looks the same any direction we look ◦ Laws of physics are the same everywhere(when)

7  General Relativity ◦ theory of gravity  Standard Model of Particle Physics ◦ Constituents of normal matter ◦ Interactions between them

8 Dark Side of Cosmology ◦ Dark Matter ◦ Dark Energy Courtesy of George Lucas

9  GR predicts universe is expanding ◦ Einstein tried to fix this with L ◦ Claims its his biggest mistake  Hubble obs. recession of galaxies (1929) ◦ First evidence for universal expansion ◦ Subsequent obs. confirm this

10  If the universe is expanding…. ◦ What was it like in the past? ◦ What happens to its constituents?  Baryons- n, p, nuclides Denser Hotter Smaller

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12  At kT>1 MeV ◦ Thermal equilibrium ◦ Chemical equilibrium ◦ Main constitients  Photons  Neutrinos  Electrons/positrons  Small number of baryons (n & p) } NSE n/p = exp(-  m/T)

13  Dynamical timescale ◦ Hubble expansion rate H ~ T 2 /M P  Reaction timescales ◦ Weak interaction G W ~ T 5 /M W 4 ◦ Rxn rates G rxn ~ r B l rxn

14  When T~1 MeV ◦ G W ~H weak rates become slow  n ’s stop interacting ◦ Electrons/positrons become NR  e + + e - 2 g  energy goes into all but n ’s  T g > T n

15  n,p would like to fuse into d  But N g (E>B d ) >> N B ◦ So as soon as d is made, it is destroyed ◦ So we must wait…..  Called the D bottleneck  while we wait, n’s decay

16  T~70 keV, d not efficiently destroyed  So……. p(n, g )d(p, g ) 3 He(d,p) 4 He  We convert H into 4 He (all n’s go into 4 He)  Sometimes we even 3 He( a, g ) 7 Be  T~40 keV, Coulomb barrier halts nucl.

17 Light Element Abundances 4 He: known syst. Olive & Skillman 2004 D: few obs. systems Burles, Kirkman, O’Meara 3 He: extrap. error Bania et al, Vangioni-Flam et al 7 Li: add. syst.? Spite & Spite, Ryan et al, Bonifacio et al WMAP CMB  B h 2 Bennet et al, Spergel et al Agreemen t Disagreemen t

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19  Obs./Exp./Thry. Systematics (Cyburt 2004; Descouvemont et al. 2004; Serpico et al. 2004)  Nuclear Astrophys./Chemical Evolution (Vangioni-Flam et al. 2002; Bono et al.2002; Cassisi, Salaris & Irwin 2003)  Physics beyond Standard Model (Malaney & Mathews 1993; Sarkar 1996; Cyburt, Fields & Olive 2004)

20 Nuke fixes: Missing Reactions? Coc et al. ApJ 744 (2012) 158 Boyd et al PRD 82 (2010) Doesn’t significantly alter the final abundance predictions!!!!

21 3 He(  ) 7 Be  7 Li  S 34  Can fix 7 Li, but…  lose Solar flux  SNO+S 17 +SSM=S 34 (Ahmed et al, Cyburt et al, Bahcall)  Rule out renorm >99% 7 Be(d,p  ) 4 He  S  old value Coc et al (2004)  New expt performed Angulo et al (2005)  No impact on BBN  What about a missing resonance?  Not strong enough!!! (Cyburt & Pospelov arXiv: ) Kirseborn & Davids PRC 84 (2011) O’Malley et al PRC 84 (2011)

22 Non-thermal processes (Voronchev, Nakao, Tsukida, & Nakamura PRD 85 (2012) )  d(d,n) 3 He, d(d,p)t, 3 He(d,p) 4 He, t(d,n) 4 He  n,p from rxns are highly non-thermal  Slowed in plasma, but still partially non-thermal  Can enhance some reactions  However, thermalization is too strong at BBN T’s  Changes in abundances <1%  See also non-Maxwellian distributions (Bertulani et al arXiv: ) and electron screening affects on BBN (PRC83 (2011)

23  Obs syst errors larger or depletion?  Some evidence of Li depletion ◦ 6,7 Li(p,a) rxns deplete Li  Pre-MS stars (Molaro et al. arXiv: , Yee and Jensen ApJ 711 ( & Bildsten et al ApJ 482 (1997) 442)  MS stars (Korn et al. Nature 442 (2006) 657)  Can we deplete uniformly without increasing the observed dispersion?  Better astro models needed! (Masseron et al arXiv: ) (Lind et al. arXiv: )

24  Variation of fundamental constants?  Dark radiation or neutrino degeneracy?  Beyond the SM….. SUSY? (Cyburt, Ellis, Fields, Luo, Olive & Spanos; Kawasaki, Kohri & Moroi; Mathews, Kajino; Jedamzik )

25  BBN is the first epoch of nucleosynthesis  Involves all 4 fundamental forces of nature  Standard BBN w/ CMB is parameter free  Accurately predict light element abundances  Concordance w/ 4 He, 3 He and D obs.  7 Li remains a problem!! 6 Li is not a problem!! Steffen et al. arXiv:


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