1 / 63

630 likes | 835 Views

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.

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.
Content is provided to you AS IS for your information and personal use only.
Download presentation by click this link.
While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

**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)

More Related