slide1 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
The Universe is expanding PowerPoint Presentation
Download Presentation
The Universe is expanding

Loading in 2 Seconds...

play fullscreen
1 / 75
talia

The Universe is expanding - PowerPoint PPT Presentation

120 Views
Download Presentation
The Universe is expanding
An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  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!

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

  3. History of nmeasurements Statistical Errors versus SystematicErrors! 885.7  0.8 sec

  4. 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.

  5. Pre - BBN Post - BBN Only n & p Mainly H & 4He

  6. Baryon Density Parameter : B Note : Baryons  Nucleons B  nN /n ; 10   B= 274 Bh2 (ηB not predicted (yet) by fundamental theory) Hubble Parameter : H = H(z) In The Early Universe: H2 α Gρ

  7. “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

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

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

  10. Two pathways to mass - 7 For η10 ≥ 3, more nucleons  more mass - 7

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

  12. 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 Y4He Mass Fraction Y 4y/(1 + 4y) y  n(He)/n(H) YP DOES depend on the competition between Γwk & H

  13. 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

  14. 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 + 7N /43)1/2 • where ´   + N andN  3 + N

  15. The Expansion Rate Parameter (S) Is A Probe Of Non-Standard Physics • S2  (H/ H)2= G/G  1 + 7N /43 • * S may be parameterized by N N (-) /  and N  3 + N NOTE : G/ G = S2 1 + 7N / 43 • 4He is sensitive to S (N) ; D probes B

  16. 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 (S)

  17. 4Heis an early – Universe Chronometer Y vs. D/H N =2, 3, 4 (S = 0.91, 1.00, 1.08) Y0.013N 0.16 (S – 1)

  18. 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)

  19. 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)

  20. Post – BBN Evolution • As gas cycles through stars,D is only DESTROYED • As gas cycles through stars,3He is DESTROYED , • PRODUCED and, some 3HeSURVIVES • Stars burn H to 4He (and produce heavy elements) •  4HeINCREASES (along with CNO …) • Cosmic Rays and SOME Stars PRODUCE7Li BUT, • 7Li is DESTROYED in most stars

  21. 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) • (D/H) P is sensitive to the baryon density (  B − ) • H  and D areobserved in Absorption in High – z, • Low – Z, QSO Absorption Line Systems (QSOALS)

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

  23. Observing D in QSOALS Ly -  Absorption

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

  25. log (D/H) vs. Oxygen Abundance log(105(D/H)P) = 0.45 ± 0.03 Caveat Emptor !  10(SBBN) = 5.81 ± 0.28

  26. 3He Observed In Galactic H Regions 3He/H vs. O/H No Clear Correlation With O/H Stellar Produced ? (3He/H)P for B = B(SBBN + D) 3He Consistent With SBBN

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

  28. 3He Observed In Galactic HII Regions No clear correlation with R More gas cycled through stars Stellar Produced ? Less gas cycled through stars SBBN

  29. 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

  30. 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)

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

  32. YP(IT10) = 0.2565 ± 0.0010 ± 0.0050 YP = 0.2565 ± 0.0060

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

  34. YP(IT10) = 0.2565 ± 0.0010 ± 0.0050 YP(AOS10) = 0.2573 ± 0.0028 ± ??

  35. For SBBN (N = 3) • If : log(D/H)P = 0.45 ± 0.03  • η10 = 5.81 ± 0.28 YP = 0.2482 ± 0.0005 • YP(OBS) − YP(SBBN) = 0.0083 ± 0.0060 • YP(OBS) = YP(SBBN) @ ~ 1.4 σ

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

  37. SBBN Predictions Agree With Observations Of D, 3He, 4He, But NOT With 7Li For BBN (with η10 & N (S) as free parameters) BBN Abundances Are Functions of η10 & S

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

  39. Isoabundance Contours for 105(D/H)P & YP YP &yD  105 (D/H) 0.26 4.0 3.0 2.0 0.25 0.24

  40. Isoabundance Contours for 105(D/H)P & YP YP&yD  105 (D/H) 0.26 4.0 3.0 2.0 0.25 0.24

  41. log(D/H)P = 0.45 ± 0.03 & YP = 0.2565 ± 0.0060 •  η10 = 6.07 ± 0.34 & N = 3.62 ± 0.46 • N = 3 @ ~ 1.3 σ

  42. Lithium Isoabundance Contours [Li]P = 12 + log(Li/H) 2.6 2.7 2.8

  43. Even for N  3 , [Li]P > 2.6 [Li]P = 12 + log(Li/H) 2.6 2.7 2.8

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

  45. BBN (~ 3 Minutes) , The CMB (~ 400 kyr) , LSS (~ 10 Gyr) Provide Complementary Probes Of The Early Evolution Of The Universe * 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 SBBN = SCMB = 1 ?

  46. CMB ΔT Δ ΔTrms vs. Δ: Temperature Anisotropy Spectrum

  47. 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

  48. CMB Temperature Anisotropy Spectrum Depends On The Baryon Density 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