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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 …. Rates set by n.

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## The Universe is expanding

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**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 + en + e … Rates set byn “Freeze – Out” ? Wrong! (n/p)eq BBN “Begins” Decay**History of nmeasurements**Statistical Errors versus SystematicErrors! 885.7 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 tBBN 4 24 min.**Pre - BBN**Post - BBN Only n & p Mainly H & 4He**Baryon Density Parameter : B**Note : Baryons Nucleons B nN /n ; 10 B= 274 Bh2 Hubble Parameter : H = H(z) In The Early Universe: H2 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, 3He, 4He, 7Li are predicted as a function of only one parameter : * The baryon to photon ratio : B**Evolution of mass - 2**10 More nucleons less D**Two pathways to mass - 3**More nucleons less mass - 3**BBN abundances of masses – 6, 9 –11**Abundances Are Very Small !**Y is very weakly dependent on the nucleon abundance**All/most neutrons are incorporated in 4He n/p 1/7 Y 2n /(n + p) 0.25 Y4He Mass Fraction Y 4y/(1 + 4y) y n(He)/n(H) YP DOES depend on the competition between Γwk & H**SBBN – Predicted Primordial Abundances**4He Mass Fraction Mostly H &4He BBN Abundances ofD, 3He, 7Li are RATE (DENSITY) LIMITED 7Li 7Be D, 3He, 7Li are potential BARYOMETERS**Use BBN (D/H) P vs. 10to constrain B**Predict (D/H)P “Measure” (D/H) P Infer B (B) at ~ 20 Min.**4He (mass fraction Y) is NOT Rate Limited**• 4He IS n/p Limited Y is sensitive to the EXPANSION RATE ( H 1/2 ) • Expansion Rate Parameter : S H´/H • S H´/H (´/)1/2 (1 + 7N /43)1/2 • where ´ + N andN 3 + N**The Expansion Rate Parameter (S)**Is A Probe Of Non-Standard Physics • S2 (H/ H)2= G/G 1 + 7N /43 • * S may be parameterized by N N (-) / and N 3 + N NOTE : G/ G = S2 1 + 7N / 43 • 4He is sensitive to S (N) ; D probes B**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, 3He, 4He, 7Li are predicted as a function of two parameters : * The baryon to photon ratio : B (SBBN) * The effective number of neutrinos : N**4Heis an early – Universe Chronometer**Y vs. D/H N =2, 3, 4 (S = 0.91, 1.00, 1.08) Y0.013N 0.16 (S – 1)**Isoabundance Contours for 105(D/H)P & YP**YP & yDP 105 (D/H)P 4.0 2.0 3.0 0.25 0.24 0.23 D&4HeIsoabundance Contours Kneller & Steigman (2004)**Kneller & Steigman (2004) & Steigman (2007)**yDP 105(D/H)P = 46.5 (1 ± 0.03) D-1.6 YP = (0.2386 ±0.0006) + He / 625 y7 1010(7Li/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)**Post – BBN Evolution**• As gas cycles through stars,D is only DESTROYED • As gas cycles through stars,3He is DESTROYED , • PRODUCED and, some 3He SURVIVES • Stars burn H to 4He (and produce heavy elements) • 4He INCREASES (along with CNO) • Cosmic Rays and SOME Stars PRODUCE 7Li BUT, • 7Li is DESTROYED in most stars**Observing D in QSOALS**Ly - Absorption**D/H vs. number of H atoms per cm2**Observations of Deuterium In 7 High-Redshift, Low-Metallicity QSO Absorption Line Systems 105(D/H)P = 2.7 ± 0.2 (Weighted Mean of D/H) (Weighted mean of log (D/H) 105(D/H)P = 2.8 ± 0.2)**log (D/H) vs. Oxygen Abundance**log(105(D/H)P) = 0.45 ± 0.03**(D/H)obs + BBNpred10 =6.0± 0.3**BBN V. Simha & G. S.**CMB**ΔT Δ ΔTrms vs. Δ: Temperature Anisotropy Spectrum**CMB Temperature Anisotropy Spectrum**(T2 vs. ) Depends On The Baryon Density 10=4.5,6.1,7.5 V. Simha & G. S. The CMB provides an early - Universe Baryometer**CMB + LSS10 =6.1±0.2**10Likelihood CMB V. Simha & G. S.**D/H vs. number of H atoms per cm2**Observations of Deuterium In 7 High-Redshift, Low-Metallicity QSO Absorption Line Systems BBN + CMB/LSS 105(D/H)P = 2.6 ± 0.1**BBN (~ 20 min) & CMB (~ 380 kyr) AGREE**10Likelihoods CMB BBN V. Simha & G. S.**3He Observed In Galactic HII Regions**No clear correlation with O/H Stellar Produced ? SBBN**Oxygen Gradient In The Galaxy**More gas cycled through stars Less gas cycled through stars**3He Observed In Galactic HII Regions**No clear correlation with R Stellar Produced ? SBBN**The 4He abundance is measured via H and He**recombination lines from metal-poor, extragalactic H regions (Blue, Compact Galaxies). Theorist’s H Region Real 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(YP)≈ 0.006, NOT < 0.001 ! Note : ΔY = (ΔY/ΔZ) Z <<σ(YP)**4He (YP) Observed In Extragalactic H Regions**As O/H 0, Y 0 SBBN Prediction: YP≈ 0.249 K. Olive**SBBN 10Likelihoods from D and 4He**AGREE ? to be continued …**Lithium – 7 Is A Problem**[Li] ≡ 12 + log(Li/H) [Li]SBBN 2.6 – 2.7 [Li]OBS 2.1 Li too low !**More Recent Lithium – 7 Data**[Li] ≡ 12 + log(Li/H) [Li]SBBN 2.70 ± 0.07 NGC 6397 Asplund et al. 2006 Boesgaard et al. 2005 Aoki et al. 2009 Lind et al. 2009 Where is the Spite Plateau ?**YP vs. (D/H)P for N = 2, 3, 4**N 3 ? But, new (2010) analyses now claim YP = 0.256 ± 0.006 !**A Non-Standard BBN Example (Neff < 3)**Late Decay of a Massive Particle Kawasaki,Kohri&Sugiyama & Low Reheat Temp. (TR MeV) Neff<3 Relic Neutrinos Not Fully (Re)Populated**Isoabundance Contours for 105(D/H)P & YP**YP & yD 105 (D/H) 4.0 3.0 2.0 0.25 0.24 0.23 Kneller & Steigman (2004)**Nvs.10 From BBN (D & 4He)**( YP < 0.255 @ 2 σ ) BBN Constrains N N < 4 N> 1 V. Simha & G. S.**CMB Temperature Anisotropy Spectrum**Depends on the Radiation Density R(SorN) N =1, 3,5 V. Simha & G. S. The CMB / LSS is an early - Universe Chronometer**N Is Degenerate With mh2**The degeneracy can be broken - partially - by H0 (HST) and LSS 1 + zeq =m / R 1 + zeq≈ 3200 V. Simha & G. S.**CMB + LSS + HST Prior on H0**Nvs.10 CMB + LSS Constrain 10 V. Simha & G. S.**BBN (D & 4He) & CMB + LSS + HST AGREE !**N vs. 10 CMB + LSS BBN V. Simha & G. S.**But, even for N 3**Y + DH LiH 4.0 0.7 x 1010 yLi 1010 (Li/H) 4.0 3.0 2.0 0.25 4.0 0.24 0.23 Li depleted/diluted in Pop stars ? Kneller & Steigman (2004)

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