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

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

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

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.

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

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

“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 More nucleons  less D Evolution of mass - 2

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

Two pathways to mass - 7

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

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

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

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

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 )

S 2  (H/ H) 2 = G  / G    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   N / 43  N  (  -  ) /  and N  3 +  N

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

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

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

y DP  10 5 (D/H) P = 46.5 (1 ± 0.03)  D -1.6 Y P = ( ± ) +  He / 625 y 7  ( 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)

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

Ly -  Absorption Observing D in QSOALS

10 5 (D/H) P = 2.7 ± 0.2 Observations of Deuterium In 7 High-Redshift, Low-Metallicity QSO Absorption Line Systems (Weighted Mean of D/H) ( Weighted mean of log (D/H)  10 5 (D/H) P = 2.8 ± 0.2 ) D/H vs. number of H atoms per cm 2

log(10 5 (D/H) P ) = 0.45 ± 0.03 log (D/H) vs. Oxygen Abundance

BBN (D /H) obs + BBN pred   10 = 6.0 ± 0.3 V. Simha & G. S.

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

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.

 10 Likelihood CMB + LSS   10 = 6.1 ± 0.2 CMB V. Simha & G. S.

BBN + CMB/LSS  10 5 (D/H) P = 2.6 ± 0.1 D/H vs. number of H atoms per cm 2 Observations of Deuterium In 7 High-Redshift, Low-Metallicity QSO Absorption Line Systems

 10 Likelihoods BBN CMB BBN (~ 20 min) & CMB (~ 380 kyr) AGREE V. Simha & G. S.

SBBN 3 He Observed In Galactic HII Regions No clear correlation with O/H Stellar Produced ?

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

3 He Observed In Galactic HII Regions SBBN No clear correlation with R Stellar Produced ?

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

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 < ! Note : ΔY = ( ΔY / ΔZ ) Z << σ (Y P )

SBBN Prediction : Y P ≈ As O/H  0, Y  0 4 He (Y P ) Observed In Extragalactic H  Regions K. Olive

SBBN  10 Likelihoods from D and 4 He AGREE ? to be continued …

[Li] OBS  2.1 [Li] SBBN  2.6 – 2.7 Li too low ! Lithium – 7 Is A Problem [Li] ≡ 12 + log(Li/H)

More Recent Lithium – 7 Data [Li] SBBN  2.70 ± 0.07 Asplund et al Boesgaard et al Aoki et al Lind et al NGC 6397 Where is the Spite Plateau ?

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

Low Reheat Temp. (T R  MeV) Kawasaki, Kohri & Sugiyama Late Decay of a Massive Particle &  Relic Neutrinos Not Fully (Re) Populated N eff < 3 A Non-Standard BBN Example (N eff < 3)

Kneller & Steigman (2004) Isoabundance Contours for 10 5 (D/H) P & Y P Y P & y D  10 5 (D/H)

N vs.  10 From BBN (D & 4 He) ( Y P < 2 σ ) BBN Constrains N N < 4 N > 1 V. Simha & G. S.

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.  

V. Simha & G. S. N Is Degenerate With  m h 2 The degeneracy can be broken - partially - by H 0 (HST) and LSS 1 + z eq ≈ z eq =  m /  R

CMB + LSS + HST Prior on H 0 N vs.  10 CMB + LSS Constrain  10 V. Simha & G. S.

BBN (D & 4 He) & CMB + LSS + HST AGREE ! N vs.  10 BBN CMB + LSS V. Simha & G. S.

y Li  (Li/H) 4.0 But, even for N  3 Y + D  H  Li  H  4.0  0.7 x 10  10 Li depleted / diluted in Pop  stars ? Kneller & Steigman (2004)

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  Alternative to N  3 (S  1) Y P & y D  10 5 (D/H) D & 4 He Isoabundance Contours Kneller & Steigman (2004) Y P probes  e Lepton Asymmetry

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

For N = 3 :  e =  &  10 = 5.9  0.4  e Degeneracy (Non – Zero Lepton Number) Y P & y D  10 5 (D/H) (V. Simha & G. S.)

BBN Constraints (D & 4 He) On  e For N = 3 V. Simha & G.S.  10 = 5.9 ± 0.3  e = ± 0.026

Even With Non - Zero e Degeneracy, The 7 Li Problem Persists [Li] = 2.6  0.7 Still ! Li depleted / diluted in Pop  stars ? y Li  ( 7 Li/H) [Li] = 2.7  0.7 with CFO 2008 results Or, Late Decay of (Charged) NLSP ?

BBN & The CBR Provide Complementary Probes Of The Early Universe Do predictions and observations of the baryon density parameter (  B ) and the expansion rate parameter (S or N ) agree at 20 minutes and at 400 kyr ?

BBN (D & 4 He) & CMB + LSS + HST AGREE ! N vs.  10 BBN CMB + LSS V. Simha & G. S.

Several consequences of the good agreement between BBN and CMB + LSS Entropy Conservation : N  (CMB) / N  (BBN) = 0.92 ± 0.07 Modified Radiation Density (late decay of massive particle) ρ R CMB / ρ R BBN = Variation in the Gravitational Constant ? G BBN / G 0 = 0.91 ± 0.07 ; G CMB / G 0 = 0.99 ± 0.12

BBN + CMB + LSS Combined Fit N vs.  10 V. Simha & G.S. ( Y P < 2 σ ) N = 2.5 ± 0.4  10 = 6.1 ± 0.1

N &  e BOTH FREE, BBN + CMB/LSS V. Simha & G.S. Consistent with  e = 0 & N = 3 N = 3.3 ± 0.7  e = ± 0.046

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)