1. The Universe is expanding The Universe is filled with radiation The Early Universe was Hot & Dense  The Early Universe was a Cosmic Nuclear Reactor!

3. Neutron Abundance vs. Time / Temperature p + e   n + e … (n/p) eq BBN “Begins”  Decay “Freeze – Out” ? Wrong! Rates set by  n

4. Statistical Errors versus Systematic Errors ! History of  n measurements 885.7  0.8 sec

6. BBN “Begins” at T  70 keV when n / p  1 / 7 Coulomb Barriers and absence of free neutrons terminate BBN at T  30 keV t BBN  4  24 min.

7. Pre - BBNPost - BBN Only n & p Mainly H & 4 He

8. Baryon Density Parameter :  B Note : Baryons  Nucleons  B  n N / n  ;  10     B = 274  B h 2 Hubble Parameter : H = H(z) In The Early Universe : H 2 α Gρ (η B not predicted (yet) by fundamental theory)

9. “Standard” Big Bang Nucleosynthesis (SBBN) An Expanding Universe Described By General Relativity, Filled With Radiation, Including 3 Flavors Of Light Neutrinos (N = 3) The relic abundances of D, 3 He, 4 He, 7 Li are predicted as a function of only one parameter : * The baryon to photon ratio :  B

10.  10 More nucleons  less D Evolution of mass - 2

11. More nucleons  less mass - 3 Two pathways to mass - 3

12. Two pathways to mass - 7 For η 10 ≥ 3, more nucleons  more mass - 7

13. BBN abundances of masses – 6, 9 – 11 Abundances Are Very Small !

14. n / p  1 / 7  Y  2n / (n + p)  0.25 All / most neutrons are incorporated in 4 He Y is very weakly dependent on the nucleon abundance Y  4 He Mass Fraction Y  4y/(1 + 4y) y  n(He)/n(H) Y P DOES depend on the competition between Γ wk & H

15. BBN Abundances of D, 3 He, 7 Li are RATE (DENSITY) LIMITED D, 3 He, 7 Li are potential BARYOMETERS SBBN – Predicted Primordial Abundances 7 Li 7 Be 4 He Mass Fraction Mostly H & 4 He

16. 4 He (mass fraction Y) is NOT Rate Limited Expansion Rate Parameter : S  H´/ H S  H´/ H  (  ´ /  ) 1/2  (1 + 7  N / 43) 1/2 where  ´   +  N  and N  3 +  N 4 He IS n/p Limited  Y is sensitive to the EXPANSION RATE ( H   1/2 )

17. S 2  (H/ H) 2 = G  / G   1 + 7  N / 43 * S may be parameterized by  N The Expansion Rate Parameter (S) Is A Probe Of Non-Standard Physics 4 He is sensitive to S (N ) ; D probes  B NOTE : G/ G = S 2  1 + 7  N / 43  N  (  -  ) /  and N  3 +  N

18. Big Bang Nucleosynthesis (BBN) An Expanding Universe Described By General Relativity, Filled With Radiation, Including N Flavors Of Light Neutrinos The relic abundances of D, 3 He, 4 He, 7 Li are predicted as a function of two parameters : * The baryon to photon ratio :  B (SBBN) * The effective number of neutrinos : N (S)

19. N = 2, 3, 4 4 He is an early – Universe Chronometer (S = 0.91, 1.00, 1.08)  Y  0.013  N  0.16 (S – 1) Y vs. D / H

20. 0.23 0.24 0.25 4.0 3.0 2.0 Y P & y DP  10 5 (D/H) P D & 4 He Isoabundance Contours Kneller & Steigman (2004) Isoabundance Contours for 10 5 (D/H) P & Y P

21. y DP  10 5 (D/H) P = 46.5 (1 ± 0.03)  D -1.6 Y P = (0.2386 ± 0.0006) +  He / 625 y 7  10 10 ( 7 Li/H) = (1.0 ± 0.1) (  LI ) 2 / 8.5 where :  D   10 – 6 (S – 1)  He   10 + 100 (S – 1)  Li   10 – 3 (S – 1) Kneller & Steigman (2004) & Steigman (2007)

22. Post – BBN Evolution As gas cycles through stars, D is only DESTROYED Stars burn H to 4 He (and produce heavy elements)  4 He INCREASES (along with CNO …) As gas cycles through stars, 3 He is DESTROYED, PRODUCED and, some 3 He SURVIVES Cosmic Rays and SOME Stars PRODUCE 7 Li BUT, 7 Li is DESTROYED in most stars

23. DEUTERIUM Is The Baryometer Of Choice The Post – BBN Evolution of D is Simple : As the Universe evolves, D is only DESTROYED  * Anywhere, Anytime : (D/H) t  (D/H) P * For Z << Z  : (D/H) t  (D/H) P (Deuterium Plateau) H  and D  are observed in Absorption in High – z, Low – Z, QSO Absorption Line Systems (QSOALS) (D/H) P is sensitive to the baryon density (   B −  )

24. “Measure” ( D / H ) P Use BBN ( D / H ) P vs.  10 to constrain  B Infer  B (  B ) at ~ 20 Min. Predict (D/H) P

25. Ly -  Absorption Observing D in QSOALS

26. Observations of Deuterium In 7 High - Redshift, Low - Metallicity QSOALS (Pettini et al. 2008) log (D/H) vs. Oxygen Abundance Where is the D – Plateau ?

27. log(10 5 (D/H) P ) = 0.45 ± 0.03 log (D/H) vs. Oxygen Abundance   10 (SBBN) = 5.81 ± 0.28 Caveat Emptor !

28. 3 He/H vs. O/H No Clear Correlation With O/H Stellar Produced ? 3 He Consistent With SBBN 3 He Observed In Galactic H  Regions ( 3 He/H) P for  B =  B (SBBN + D)

29. Oxygen Gradient In The Galaxy More gas cycled through stars Less gas cycled through stars

30. 3 He Observed In Galactic HII Regions SBBN No clear correlation with R Stellar Produced ? More gas cycled through stars Less gas cycled through stars

31. The 4 He abundance is measured via H and He recombination lines from metal-poor, extragalactic H  regions (Blue, Compact Galaxies). Theorist’s H  RegionReal H  Region

32. In determining the primordial helium abundance, systematic errors (underlying stellar absorption, temperature variations, ionization corrections, atomic emissivities, inhomogeneities, ….) dominate over the statistical errors and the uncertain extrapolation to zero metallicity.  σ (Y P ) ≈ 0.006, NOT < 0.001 ! Note : ΔY = ( ΔY / ΔZ ) Z << σ (Y P )

33. Izotov & Thuan 2010 4 He Observed in Low – Z Extragalactic H  Regions

34. Y P ( IT10 ) = 0.2565 ± 0.0010 ± 0.0050  Y P = 0.2565 ± 0.0060

35. Aver, Olive, Skillman 2010 Izotov & Thuan 2010

36. Y P ( IT10 ) = 0.2565 ± 0.0010 ± 0.0050 Y P ( AOS10 ) = 0.2573 ± 0.0028 ± ??

37. For SBBN (N = 3) If : log(D/H) P = 0.45 ± 0.03  η 10 = 5.81 ± 0.28  Y P = 0.2482 ± 0.0005 Y P (OBS) − Y P (SBBN) = 0.0083 ± 0.0060  Y P (OBS) = Y P (SBBN) @ ~ 1.4 σ

38. But ! Lithium – 7 Is A Problem [Li] ≡ 12 + log(Li/H) [Li] SBBN = 2.66 ± 0.06 Where is the Lithium Plateau ? Asplund et al. 2006 Boesgaard et al. 2005 Aoki et al. 2009 Lind et al. 2009 SBBN Li/H vs. Fe/H

39. For BBN (with η 10 & N (S) as free parameters) BBN Abundances Are Functions of η 10 & S SBBN Predictions Agree With Observations Of D, 3 He, 4 He, But NOT With 7 Li

40. Y P vs. (D/H) P for N = 2, 3, 4 N  3 ? But, new (2010) analyses now claim Y P = 0.257 ± 0.006 !

41. Isoabundance Contours for 10 5 (D/H) P & Y P Y P & y D  10 5 (D/H) 4.03.02.0 0.24 0.25 0.26

42. Y P & y D  10 5 (D/H) 0.26 0.25 0.24 Isoabundance Contours for 10 5 (D/H) P & Y P 4.03.02.0

43. log(D/H) P = 0.45 ± 0.03 & Y P = 0.2565 ± 0.0060  η 10 = 6.07 ± 0.34 & N = 3.62 ± 0.46  N = 3 @ ~ 1.3 σ

44. 2.62.72.8 Lithium Isoabundance Contours [Li] P = 12 + log(Li/H)

45. 2.62.72.8 Even for N  3, [Li] P > 2.6 [Li] P = 12 + log(Li/H)

46. Lithium – 7 Is STILL A Problem [Li] ≡ 12 + log(Li/H) [Li] BBN = 2.66 ± 0.07 BBN [Li] OBS too low by ~ 0.5 – 0.6 dex

47. * Do the BBN - predicted abundances agree with observationally - inferred primordial abundances ? Do the BBN and CMB values of  B agree ? Do the BBN and CMB values of S (N ) agree ? Is S BBN = S CMB = 1 ? BBN (~ 3 Minutes), The CMB (~ 400 kyr), LSS (~ 10 Gyr) Provide Complementary Probes Of The Early Evolution Of The Universe

48. CMB ΔTΔT ΔΔ ΔT rms vs. Δ  : Temperature Anisotropy Spectrum

49. CMB Temperature Anisotropy Spectrum (  T 2 vs.  ) Depends On The Baryon Density The CMB provides an early - Universe Baryometer    10 = 4.5, 6.1, 7.5 V. Simha & G. S.

50.  10 (CMB) = 6.190 ± 0.145 (Komatsu et al. 2010) For N = 3, is  B (CMB) =  B (SBBN) ?  10 (SBBN) = 5.81 ± 0.28 SBBN & CMB Agree Within ~ 1.2 σ CMB Temperature Anisotropy Spectrum Depends On The Baryon Density

51. Likelihood Distributions For η 10 SBBNCMB

52. At BBN, With η 10 & N As Free Parameters η 10 (BBN) = 6.07 ± 0.34 At REC, With CMB (WMAP 7 Year Data) + LSS η 10 (REC) = 6.190 ± 0.145 η 10 (BBN) & η 10 (REC) Agree  η 10 (REC) − η 10 (BBN) = 0.12 ± 0.37

53. Likelihood Distributions For η 10 BBNCMB

54. CMB Temperature Anisotropy Spectrum Depends on the Radiation Density  R (S or N ) The CMB / LSS is an early - Universe Chronometer N = 1, 3, 5 V. Simha & G. S.  

55. At BBN, With η 10 & N As Free Parameters N (BBN) = 3.62 ± 0.46  N (BBN) = 3 @ ~ 1.3 σ At REC, With CMB (WMAP 7 Year Data) + LSS N (REC) = 4.30 ± 0.87  N (REC) = 3 @ ~ 1.5 σ N (BBN) & N (REC) Agree  N (REC) − N (BBN) = 0.68 ± 0.98

56. BBNCMB Likelihood Distributions For N

57. BBNCMB N = 3

58. SBBN IS Consistent With D, 3 He, 4 He And Agrees With The CMB + LSS + H 0 CONCLUSION # 1 (But, Lithium Is A Problem !) Post – BBN Decay of Massive Particles ? Annihilation of Dark Matter Relics ? Li depleted / diluted in Pop  Stars ?

59. Non - standard BBN (N ≠ 3, S ≠ 1) With  10 = 6.07 ± 0.34 & N = 3.62 ± 0.46 IS Consistent With D, 3 He, & 4 He And With The CMB + LSS (But, 7 Li ?) CONCLUSION # 2 BBN + CMB Combined Can Constrain Non-standard Cosmology & Particle Physics

60. Entropy (CMB Photon) Conservation * In a comoving volume, N  = N B / η B * For conserved baryons, N B = constant * Comparing η B at BBN and at Recombination  N  (REC) / N  (SBBN) = 0.94 ± 0.05  N  (REC) / N  (BBN) = 0.98 ± 0.06 Comparing BBN And The CMB

61. Variation of the Gravitational Constant Between BBN, Recombination, and Today ? G / G = S 2 = 1 + 7  N / 43 G (BBN) / G 0 = 1.10 ± 0.08 G (REC) / G 0 = 1.21 ± 0.14

62. “Extra” Radiation Density ? Example : Late decay of a massive particle Recall that : ρ R / ρ R = S 2  1 + 7  N / 43 In the absence of the creation of new radiation (via decay ?), S (BBN) = S (REC) Comparing N at BBN and at Recombination  N (REC) − N (BBN) = 0.68 ± 0.98

63. For N ≈ 3, BBN (D, 3 He, 4 He) Agrees With The CMB + LSS CONCLUSIONS BBN + CMB + LSS Constrain Cosmology & Particle Physics (But, Lithium Is A Problem !)

64. CHALLENGES Why is the spread in D abundances so large ? Why is 3 He/H uncorrelated with O/H and / or R ? What (how big) are the systematic errors in Y P ? Are there observing strategies to reduce them ? What is the primordial abundance of 7 Li ( 6 Li) ? We (theorists) need more (better) data !

66. e Degeneracy (Non – Zero Lepton Number) For  e =  e / kT  0 (more e than anti - e ) n / p  exp (−  m / kT −  e )  n / p   Y P  Lepton Asymmetry Y P probes  e (Lepton Asymmetry)

67. y DP  10 5 (D/H) P = 46.5 (1 ± 0.03)  D -1.6 Y P = (0.2386 ± 0.0006) +  He / 625 y 7  10 10 ( 7 Li/H) = (1.0 ± 0.1) (  LI ) 2 / 8.5 where :  D   10 + 5  e / 4  He   10 – 574  e / 4  Li   10 – 7  e / 4 Kneller & Steigman (2004) & Steigman (2007)

68. Isoabundance Contours for 10 5 (D/H) P & Y P 4.03.02.0 0.24 0.25 0.26 Y P & y D  10 5 (D/H)

69. log(D/H) P = 0.45 ± 0.03 & Y P = 0.2565 ± 0.0060  η 10 = 5.82 ± 0.28 &  e = − 0.036 ± 0.026

70. 4.03.02.0 0.24 0.25 0.26 Isoabundance Contours for 10 5 (D/H) P & Y P Y P & y D  10 5 (D/H)

71. Likelihood Distribution for ξ e BBN

72. 2.62.72.8 Lithium Isoabundance Contours [Li] P = 12 + log(Li/H)

73. 2.82.62.7 [Li] P = 12 + log(Li/H) Even for  e  0, [Li] P > 2.6

74. Lithium – 7 Is STILL A Problem [Li] ≡ 12 + log(Li/H) [Li] BBN = 2.66 ± 0.07 BBN [Li] OBS too low by ~ 0.5 – 0.6 dex

75. BBN (D, 3 He, 4 He) Agrees With The CMB + LSS (For N ≈ 3 &  e ≈ 0 ) CONCLUSIONS BBN + CMB + LSS Combined Can Constrain Non-Standard Cosmology & Particle Physics (But, 7 Li is a problem)