Big Bang Nucleosynthesis

Transcription

1 Big Bang Nucleosynthesis BBN and the early Universe Observations and Comparison with Theory - D/H - 4 He - 7 Li

2 Historical Perspective Intimate connection with CMB Conditions for BBN: Require T > 100 kev t < 200 s σv(p + n D + γ) cm 3 /s Today: and n B ~ 1/σvt ~ cm -3 n Bo ~ 10-7 cm -3 n B ~ R -3 ~ T 3 Predicts the CMB temperature T o = (n Bo / n B ) 1/3 T BBN ~10 K Alpher Herman Gamow

3 WMAP best fit B h 2 = ± =6.16 ± 0.16

4 Conditions in the Early Universe: T > 1 MeV ρ = π2 30 ( N ν)t 4 η = n B /n γ β-equilibrium maintained by weak interactions Freeze-out at 1 MeV determined by the competition of expansion rate H T 2 /M p and the weak interaction rate Γ G 2 FT 5 n + e + p + ν e n + ν e p + e n p + e + ν e At freezeout n/p fixed modulo free neutron decay, (n/p) 1/6 1/7

5 Nucleosynthesis Delayed (Deuterium Bottleneck) p + n D+γ Γ p n B σ p + n D+γ Γ d n γ σe E B/T Nucleosynthesis begins when Γ p Γ d n γ n B e E B/T T 0.1 MeV All neutrons 4 He Remainder: Y p = 2(n/p) 1 + (n/p) 25% D, 3 He 10 5 and 7 Li by number

6 Decline: BBN could not explain the abundances (or patterns) of all the elements. growth of stellar nucleosynthesis

7 10 11 H Abundance (Si = 10 6 ) Li He C B Be N O F Ne Mg Si Na Al P S Cl Ar Ca K Z Sc Ti Cr V Fe Mn Co Ni Cu Zn Ge Se Kr Sr Ga Br As Rb Y

8 Decline: BBN could not explain the abundances (or patterns) of all the elements. growth of stellar nucleosynthesis But, Questions persisted: 25% (by mass) of 4 He? D? Resurgence: BBN could successfully account for the abundance of D, 3 He, 4 He, 7 Li.

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10 Table 1: Key Nuclear Reactions for BBN Source Reactions NACRE d(p, γ) 3 He d(d, n) 3 He d(d, p)t t(d, n) 4 He t(α, γ) 7 Li He(α, γ) 7 Be Li(p, α) 4 He (b) (d) (c) SKM p(n, γ)d He(d, p) 4 He Be(n, p) 7 Li This work 3 He(n, p)t (a) PDG τ n NACRE Cyburt, Fields, KAO Nollett & Burles Coc et al.

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13 Big Bang Nucleosynthesis Production of the Light Elements: D, 3 He, 4 He, 7 Li 4 He observed in extragalctic HII regions: abundance by mass = 25% 7 Li observed in the atmospheres of dwarf halo stars: abundance by number = D observed in quasar absorption systems (and locally): abundance by number = 3 x He in solar wind, in meteorites, and in the ISM: abundance by number = 10-5

14 D/H All Observed D is Primordial! Observed in the ISM and inferred from meteoritic samples (also HD in Jupiter) D/H observed in Quasar Absorption systems Absorption Line Systems QSO z em z abs log N(H i) [O/H] a log (D/H) (cm 2 ) HS ± ± 0.04 Q ± ± 0.04 Q ± 0.06 < 0.70 c 4.40 ± 0.07 SDSS J ± 0.05 < 1.9 d 4.69 ± 0.13 Q ± ± 0.05 SDSS J ± ± 0.15 SDSS J ± ± SDSS J ± ± 0.06 Q ± 0.02 < ± 0.04 Q ± ± 0.09 Q ± ± CTQ ± ± 0.11

15 Tytler, O Meara, Suzuki, Lubin

16 D/H abundances in Quasar apsorption systems 8 7 BBN Prediction: 10 5 D/H = 2.54 ± 0.17 Obs Average: 10 5 D/H = 3.01 ± 0.21 (sample variance of 0.68) D/H x z

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18 4 He Measured in low metallicity extragalactic HII regions (~100) together with O/H and N/H Y P = Y(O/H 0) He is Primordial! Y O/H

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20 4 He Measured in low metallicity extragalactic HII regions together with O/H and N/H Aver, Olive, Skillman

21 ) β) W (Hβ)+a H (Hβ) W Results (Hβ) for 1+ He C R dominated (λ) by systematic effects W (λ)+a H (λ) W (λ) 1+ C R (Hβ)10 f(λ)c(hβ). (2.3) x measured helium emission line fluxes (λ3889, 4026, 4471, hydrogen emission line fluxes (Hα, Hγ, Hδ), each relative r equivalent widths (W (λ)) are used. The predicted model Interstellar Redding (scattered by dust) Underlying Stellar Absorption Radiative Transfer Collisional Corrections ut value of y + and emissivity ratio of Hβ to the helium or ectionsmadeforreddening(c(hβ)), underlying absorption ment, and radiative transfer. The optical depth function, MCMC statistical techniques have proven effective in parameter estimation ionemissionratio, C R,arebothtemperature(T)anddensity arealsotemperaturedependent). Additionally, the hydrogen he neutral to ionized hydrogen ratio (ξ). Therefore, there are (y +,n e,a He, τ, T,C(Hβ), a H, ξ). The physical model itself, nce and correction parameters to the flux, is unchanged from Aver, Olive, Skillman

22 Using χ 2 as a discriminator

23 Marginalized χ 2 He from MCMC analysis: the bad and the good

24 Final Result

25 4 He Prediction: ± Data: Regression: ± Mean: ±

26 Li/H Measured in low metallicity dwarf halo stars (over 100 observed) [Li] 2.0 [Li] T (K) [Fe/H]

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28 Possible sources for the discrepancy Nuclear Rates - Restricted by solar neutrino flux Coc et al. Cyburt, Fields, KAO

29 BBN Li sensitivites 7 Li/ 7 Li 0 = i R i i Key Rates: 3 He (α,γ) 7 Be 10. Reaction/Parameter sensitivities (α i ) η 10 / n(p, γ)d He(α, γ) 7 Be He(d, p) 4 He 0.78 d(d, n) 3 He Be(n, p) 7 Li 0.71 Newton s G N 0.66 d(p, γ) 3 He n-decay N ν,eff / He(n, p)t 0.25 d(d, p)t Li(p, α) 4 He t(α, γ) 7 Li t(d, n) 4 He t(p, γ) 4 He Be(n, α) 4 He Be(d, p)2 4 He

30 Require: S NEW 34 (0) = kevb } S 34 S 34 = 0.47 S NEW or 34 (0) = kevb S 34 S 34 = 0.73 } } globular cluster Li halo star Li New 3 He(α,γ) 7 Be measurements Constrained from solar neutrinos S 34 > 0.35 kev barn at 95% CL

31 Resonant Reactions Cyburt, Pospelov Chakraborty, Fields, Olive Broggini, Canton, Fiorentini, Villante Is there a missing excited state providing a resonant reaction? actions to establish notatio 7 Be + A C B + D In principle, long list of possible resonance candidates 7 Excited states of 8 Li (included) 8 Be (some included) - large Eres 8 B (included) 9 B - interesting state at MeV

32 7 Be + d 9 B (16.71)

33 10 B - interesting state at MeV 10 C - potentially interesting state at 15 MeV 11 C - negligible effect Be + 3 He eg. if a 1 - or 2 - excited state of 10 C were near 15.0 MeV...

34 10 B - interesting state at MeV 10 C - potentially interesting state at 15 MeV 11 C - negligible effect Be + 3 He eg. if a 1 - or 2 - excited state of 10 C were near 15.0 MeV... Preliminary report from ORSAY SPLIT-POLE spectrometer Possible E x =15.05 MeV (E r =50 kev) level reported by A. Coc - Paris Feb/12

35 Possible sources for the discrepancy Nuclear Rates - Restricted by solar neutrino flux Stellar Depletion - lack of dispersion in the data, 6 Li abundance - standard models (<.05 dex), models ( dex) Vauclaire & Charbonnel Pinsonneault et al. Richard, Michaud, Richer Korn et al.

36 Possible sources for the discrepancy Nuclear Rates - Restricted by solar neutrino flux Coc et al. Cyburt, Fields, KAO Stellar Depletion - lack of dispersion in the data, 6 Li abundance - standard models (<.05 dex), models ( dex) Stellar parameters Vauclaire & Charbonnel Pinsonneault et al. Richard, Michaud, Richer dli dlng =.09.5 dli dt = K

37 Possible sources for the discrepancy Nuclear Rates - Restricted by solar neutrino flux Coc et al. Cyburt, Fields, KAO Stellar parameters dli dlng =.09.5 dli dt = K Particle Decays

38 Limits on Unstable particles due to Electromagnetic/Hadronic Production and Destruction of Nuclei 3 free parameters ζ X = n X m X /nγ = m X Y X η, m X, and τ X Start with non-thermal injection spectrum (Pythia) Evolve element abundances including thermal (BBN) and non-thermal processes.

39 E.g., Gravitino decay Cyburt, Ellis, Fields, Luo, Olive, Spanos eg! f f, e G! + W (H ), e G! 0i (Z), e G! 0i H 0 i e G! gg. plus relevant 3-body decays

40 D/H 3e-05 Injection of p,n with timescale of ~1000 s 7 Li/H 1e Be(n,p) 7 Li followed by 7 Li(p,α) 4 He Li/ Li 0.1 1e τ (sec) Jedamzik

41 D/H 3e-05 7 Li/H 1e Li/ Li 0.1 1e τ (sec) Jedamzik Kawasaki, Kohri, Moroi

42 Gravitino Decays and Li m 3/2 = 250 GeV m 3/2 = 250 GeV = 500 GeV = 750 GeV = 500 GeV = 750 GeV = 1000 GeV = 1000 GeV = 5000 GeV = 5000 GeV Cyburt, Ellis, Fields, Luo, Olive, Spanos

43 x x x x x Based on m 1/2 = 300 GeV, tan β =10 ; B h ~ 0.2

44 x x x x x Benchmark point C, tan β =10 ; m 1/2 = 400 GeV

45 How well can you do χ 2 ( ) ( 2 Yp D H ) Li H i s 2 i, SBBN: χ 2 = field stars SBBN: χ 2 = GC stars* -8-9 Point C is probably beyond the reach of present-day interferometers. NGC 6397 appears to have a higher Li content than field stars of the same metallicity. This needs to be confirmed by a homogeneous analysis of field stars, with the same models and methods. This may or may not be related to the fact that this cluster is nitrogen rich, compared to field stars of the same metallicity (Pasquini et al. 2008). Log 3/ * from Gonzales Hernandez et al m 3/2 (GeV)

46 General feature of fixing Li: Increased D/H 4.5x x x10-10 Point C 4x10-10 Point E 3.5x x Li/H 3x Li/H 3x x x x x x x x x x x10-5 3x10-5 4x10-5 5x10-5 6x10-5 7x10-5 8x10-5 9x x x10-5 3x10-5 4x10-5 5x10-5 6x10-5 7x10-5 8x10-5 9x D/H D/H Cyburt, Ellis, Fields, Luo, Olive, Spanos Olive, Petitjean, Vangioni, Silk

47 Evolution of D, Li With post BBN processing of Li, D/H reproduces upper end of absorption data - dispersion due to in situ chemical destruction Olive, Petitjean, Vangioni, Silk

48 Effects of Bound States In SUSY models with a ~ τ NLSP, bound states form between 4 He and ~ τ The 4 He (D, γ) 6 Li reaction is normally highly suppressed (production of low energy γ) Bound state reaction is not suppressed D γ D 6 Li 4 He 6 Li 4 ( HeX ) X Pospelov

49 Possible sources for the discrepancy Stellar parameters dli dlng =.09.5 dli dt = K Particle Decays Variable Constants

50 Limits on the variations of α Cosmology - BBN - CMB The Oklo Reactor Meteoritic abundances Atomic clocks

51 Constraints from balance of weak rates vs Hubble rate G 2 FT 5 Γ(T f ) H(T f ) G N NT 2 f through He abunance n p e m/t fixed at freezeout Y 2(n/p) 1+(n/p) Sets constraints on G F, G N, N, etc.

52 Limits on Particle Properties BBN Concordance rests on balance between interaction rates and expansion rate. Allows one to set constraints on: - Particle Types - Particle Interactions - Particle Masses - Fundamental Parameters

53 How could varying α affect BBN? G 2 FT 5 Γ(T f ) H(T f ) G N NT 2 f Recall in equilibrium, n p e m/t fixed at freezeout Helium abundance, Y 2(n/p) 1+(n/p) If T f is higher, (n/p) is higher, and Y is higher

54 Limits on α from BBN Contributions to Y come from n/p which in turn come from Δm N Contributions to m N : m N aα em Λ QCD + bv Kolb, Perry, & Walker Campbell & Olive Bergstrom, Iguri, & Rubinstein Changes in α, Λ QCD, and/or v all induce changes in m N and hence Y Y Y 2 m N m N α α < 0.05 If α arises in a more complete theory the effect may be greatly enhanced: Y Y O(100) α α α and α < few 10 4

55 Approach: Consider possible variation of Yukawa, h, or fine-structure constant, α Include dependence of Λ on α; of v on h, etc. Consider effects on: Q = ΔmN, τn, BD and with h h = 1 α U 2 α U B D B D Q Q τ n τ n = [6.5(1 + S) 18R] α α = ( S 0.6R) α α = [0.2+2S 3.8R] α α, Coc, Nunes, Olive, Uzan, Vangioni Dmitriev & Flambaum

56 h/h = 0 and Effect of variations of h (S = 160) Mass fraction n 1 H 4 He H He H Li Notice effect on 7 Li Be Time (s) Coc, Nunes, Olive, Uzan, Vangioni

57 S = 240, R = 0, 36, 60, / =2 h/h Mass fraction 3 He/H, D/H He D 3 He For S = 240, R = 36, < h h < Li/H Li x 10-4 h/h

58 Summary D, He are ok -- issues to be resolved Li: Problematic - BBN 7 Li high compared to observations Important to consider: - Nuclear considerations - Resonances 10 C (15.04)! - Depletion (tuned) - Li Systematics - T scale - unlikely - Particle Decays? - Axion cooling?? - Variable Constants???