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Cosmic Chronometers: BBN and CBR Convergence in Early Universe

Explore the connection between Big Bang Nucleosynthesis and Cosmic Microwave Background to understand the early universe's baryon density. See how observations align with predictions in the first 400,000 years post-Big Bang.

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Cosmic Chronometers: BBN and CBR Convergence in Early Universe

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  1. THE EARLY UNIVERSE NEUTRINO CONNECTION GARY STEIGMAN THE OHIO STATE UNIVERSITY LEOFEST CuTAPP 2005 , Ringberg Castle , April 27, 2005

  2. ~ 100 s after the Big Bang Primordial Nucleosynthesis ~ 0.1 s after the Big Bang Neutrinos Decouple ~ 400 kyr after the Big Bang Relic Photons (CBR) are free

  3. BBN & The CBR Provide Complementary Probes Of The Early Universe Do predictions and observations of the baryon density and the expansion rate agree at 20 minutes and at 400 kyr ?

  4. Baryon Density Parameter   nN /n 10    274 Bh2 B  Bh2 where B  B /c and h  H0 / 100 km/s/Mpc  0.7 BBN – Predicted Primordial Abundances BBN Abundances of D, 3He, 7Li are RATE (DENSITY) LIMITED D, 3He, 7Li are potential BARYOMETERS

  5. DEUTERIUM --- TheBaryometerOf Choice • As the Universe evolves,D is only DESTROYED  • * Anywhere, Anytime : (D/H) t  (D/H) P • * For t << t 0 (Z << Z; z >> 0) : (D/H) t (D/H) P • (D/H) P is sensitive to the baryon density (    ) • BUT … • * H and D spectra are identical  H Interlopers? • * Unresolved velocity structure  Errors in N(H) ?

  6. Primordial D & BBN Constrain The Baryon Density

  7. Use SBBN (N = 3) (D/H) P vs. 10 “Measure” (D/H) P Infer  (B) At 20 Min.

  8. D - Abundance Data Real variations, systematic differences, statistical uncertainties ? LLS DLA Low – Z / High – z QSOALS X = O, Si, …

  9. Adopt the mean and the dispersion about the mean

  10. (D/H)P = 2.60.4 x 105 + SBBN  10 = 6.1 0.6 BBN

  11. CBR

  12. CBR Temperature Anisotropy Spectrum (T2 vs. ) Encodes The Baryon Density (B)   Barger et al. (2003) Bh2 = 0.018, 0.023, 0.028 CBR (WMAP) constrains Bh2 The CBR is (also) an early - Universe Baryometer

  13. CBR & WMAP  10 = 6.3 0.3 CBR

  14. BBN (20 min) & CBR (380 kyr) AGREE ! BBN CBR

  15. WMAP – Predicted vs. Observed D/H WMAP

  16. 4He (mass fraction Y) • is NOT Rate Limited 4Heis an early – Universe Chronometer Y vs. D/H • 4HeIS n/p Limited  • Y is sensitive to the Expansion Rate (H  1/2) N = 2, 3, 4 • Expansion Rate Parameter • S  H´/H (1 + 7N/43)1/2 • N  3+ N (S = 0.91, 1.00, 1.08) Y0.013N 0.16 (S – 1)

  17. Alternative to N  3 e – Neutrino Degeneracy YP& yD  105 (D/H) For e=e/kT  0 (more e than anti - e) n/p  exp( m/kT  e )  n/p   YP  Isoabundance Contours YP is a neutron probe Kneller & Steigman (2004)

  18. As O/H  0, Y  0 SBBN Prediction "2σ" range for YP : 0.228  0.248 (OSW)

  19. Y vs. D/H SBBN : N = 3 4He too low ?

  20. N = 2, 3, 4 N < 3 ? S < 1 ?

  21. Baryon Density () Determinations N< 3 ? Observational Uncertainties Or New Physics?

  22. CBR Temperature Anisotropy Spectrum (T2vs. ) Encodes the Radiation Density R(N)   N = 1, 2.75, 5, 7 Barger et al. (2003) CBR (WMAP) constrains N(S) The CBR is (also) an early - Universe Chronometer

  23. Joint BBN & CBR Fit N < 1 Barger et al. (2003)

  24. e – Neutrino Degeneracy YP& yD  105 (D/H) e 0.044  0.022 Bh2  0.022  0.002 (10  6.0  0.6) Kneller & Steigman (2004)

  25. CBR + BBN N= 3 Barger et al. (2003)

  26. CBR + BBN N= 4 (LSND ?) Barger et al. (2003)

  27. AsN increases, so too do eand 10 Consistent with D & 4He 10 Barger et al. (2003) • But, the CBR (WMAP) limits N and 10

  28. JOINT BBN & CBR CONTOURS (10 , e, N ALL FREE) 1 <N< 8 Barger et al. (2003)

  29. SUMMARY AND CONCLUSIONS BBN and CBR are consistent : Predictions of the Universe at 20 min and at 380 kyr AGREE ! • For e = 0 : 1.7 ≤ N ≤ 3.0 allowed @  95% • Fore 0  more freedom for N  •  0.1 ≤ e≤ 0.3 & 1 ≤ N ≤ 8 @  95%

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

  31. Look for D in the Ly -  Forest Ly -  Absorption Extra Absorption / Velocity Components?

  32. Late Decay of a Massive Particle Kawasaki,Kohri&Sugiyama & Low Reheat Temp. (TR  MeV) Neff<3  Relic Neutrinos Not Fully (Re)Populated

  33. BBN (OSW) + CBR (WMAP) CBR BBN Barger et al. (2003)

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