BIG BANG NUCLEOSYNTHESIS CONFRONTS COSMOLOGY AND PARTICLE PHYSICS
BIG BANG NUCLEOSYNTHESIS CONFRONTS COSMOLOGY AND PARTICLE PHYSICS Gary Steigman Departments of Physics and Astronomy Center for Cosmology and Astro-Particle Physics Ohio State University Horiba International Conference : COSMO/Cos. PA 2010 Tokyo, Japan, September 27 – October 1, 2010
Baryon Density Parameter : B Note : Baryons Nucleons B n. N / n ; 10 B = 274 B h 2 (ηB not predicted (yet) by fundamental theory) Hubble Parameter : H = H(z) In The Early Universe : H 2 α Gρ
Expansion Rate Parameter : S H / H S ≠ 1 is a Probe of Non - Standard Physics • Pre - e± Ann. : S 2 = G R / G R 1 + 7 N / 43 Where : N ( R - R) / and N 3 + N If R = R , GBBN / G 0 = S 2 = 1 + 0. 163 N • 4 He is sensitive to S (ΔN ) ; D probes B • Post - e± Ann. : R / R 1 + 0. 134 N Where : Neff 3. 046 + N
“Standard” Big Bang Nucleosynthesis (SBBN) For An Expanding Universe Described By General Relativity, With S = 1 (ΔN = 0) The Relic Abundances of D, 3 He, 4 He, 7 Li depend on only one parameter : ηB Big Bang Nucleosynthesis (BBN) : S ≠ 1 Relic Abundances depend on ηB and S (ΔN )
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 ΔN agree ? • Is ΔN BBN = ΔN CMB = 0 ?
SBBN – Predicted Primordial Abundances 4 He Mass Fraction Mostly H & 4 He BBN Abundances of D, 3 He, 7 Li are RATE (DENSITY) LIMITED 7 Li 7 Be D, 3 He, 7 Li are potential BARYOMETERS
Post – BBN Evolution of the Relic Abundances • As gas cycles through stars, D is only DESTROYED • As gas cycles through stars, 3 He is DESTROYED, PRODUCED and, some prestellar 3 He SURVIVES • Stars burn H to 4 He (and produce heavy elements) 4 He INCREASES (along with CNO …) • Cosmic Rays and SOME Stars PRODUCE 7 Li BUT, 7 Li is DESTROYED in most stars
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 are observed in Absorption in High – z, Low – Z, QSO Absorption Line Systems (QSOALS)
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 ?
log (D/H) vs. Oxygen Abundance log(105(D/H)P) = 0. 45 ± 0. 03 10 (SBBN) = 5. 80 ± 0. 27
3 He Observed In Galactic H Regions 3 He/H vs. O/H Stellar Produced (? ) (3 He/H)P for 3 He B = B(SBBN + D) Is Consistent With SBBN
Y vs. O / H Izotov & Thuan 2010 4 He Observed in Low – Z Extragalactic H Regions
Y vs. O / H YP(IT 10) = 0. 2565 ± 0. 0010 ± 0. 0050 YP = 0. 2565 ± 0. 0060
For SBBN (ΔN = 0) With 5 + log(D/H)P = 0. 45 ± 0. 03 YP = 0. 2482 ± 0. 0007 YP(OBS) − YP(SBBN) = 0. 0083 ± 0. 0060 YP(OBS) = YP(SBBN) @ ~ 1. 4 σ
But ! Lithium – 7 Is A Problem Li/H vs. Fe/H [Li] ≡ 12 + log(Li/H) SBBN Asplund et al. 2006 Boesgaard et al. 2005 Aoki et al. 2009 Lind et al. 2009 Where is the Lithium Plateau ?
SBBN Predictions Agree With Observations Of D, 3 He, 4 He, But NOT With 7 Li For BBN (with η 10 & ΔN (S) as free parameters) BBN Abundances Are Functions of η 10 & S (ΔN )
Isoabundance Contours for 105(D/H)P & YP YP & y. D 105 (D/H) 0. 26 4. 0 3. 0 2. 0 0. 25 0. 24
Isoabundance Contours for 105(D/H)P & YP YP & y. D 105 (D/H) 0. 26 4. 0 3. 0 2. 0 0. 25 0. 24
For BBN (ΔN ≠ 0) With 5 + log(D/H)P = 0. 45 ± 0. 03 & YP = 0. 2565 ± 0. 0060 η 10 = 6. 07 ± 0. 33 & ΔN = 0. 62 ± 0. 46 ΔN = 0 @ ~ 1. 3 σ GBBN / G 0 = 1. 10 ± 0. 07 But, what about Lithium ?
Lithium Isoabundance Contours [Li]P = 12 + log(Li/H)) 2. 6 2. 7 2. 8
Even for N 3 , [Li]P > 2. 6 [Li]P = 12 + log(Li/H)) 2. 6 2. 7 2. 8
Lithium – 7 Is STILL A Problem [Li] ≡ 12 + log(Li/H) BBN [Li]OBS too low by ~ 0. 5 – 0. 6 dex
CMB Temperature Anisotropy Spectrum Depends On The Baryon Density For ΔN = 0 , is B (CMB) = B (SBBN) ? For ΔN ≠ 0 , is B (CMB) = B (BBN) ?
Likelihood Distributions For η 10 SBBN & CMB Agree Within ~ 1. 3 σ SBBN CMB
Likelihood Distributions For η 10 BBN & CMB Agree At < 1 σ BBN CMB
At BBN, With η 10 & ΔN As Free Parameters ΔN (BBN) = 0. 62 ± 0. 46 ΔN (BBN) = 0 @ ~ 1. 3 σ At REC, With CMB (WMAP 7 Year Data) + LSS ΔN (REC) = 1. 30 ± 0. 87 ΔN (REC) = 0 @ ~ 1. 5 σ
Likelihood Distributions For N BBN & CMB Agree At < 1 σ BBN CMB
Likelihood Distributions For N N = 3 N (BBN) depends on YP N = 4 (? ) BBN CMB
Chronology of Primordial Helium Abundance Determinations
Chronology Of The BBN – Inferred Values Of N CMB
CONCLUSION # 1 SBBN IS Consistent With D, 3 He, 4 He And Agrees With The CMB + LSS + H 0 (But , Lithium Is A Problem !) • Li depleted / diluted in Pop Stars ? • Post – BBN Decay of Massive Particles ? • Annihilation of Dark Matter Relics ?
CONCLUSION # 2 Non - standard BBN (ΔN ≠ 0, S ≠ 1) IS Consistent With D, 3 He, & 4 He And With The CMB + LSS (But, not 7 Li) * BBN + CMB Combined Can Constrain Non-standard Cosmology & Particle Physics
Comparing BBN And The CMB Entropy (CMB Photon) Conservation * In a comoving volume, N = NB / ηB * For conserved baryons, NB = constant * Comparing ηB at BBN and at Recombination N (REC) / N (SBBN) = 0. 94 ± 0. 05 N (REC) / N (BBN) = 0. 98 ± 0. 06
“Extra” Radiation Density ? Example : Late decay of a massive particle Pre - e± Ann. : (ρ R / ρ R)BBN = 1 + 0. 163 N Post - e± Ann. : (ρ R / ρ R)REC = 1 + 0. 134 N In the absence of the creation of new radiation (via decay ? ) , (ρ R / ρ R)BBN = (ρ R / ρ R)REC Comparing ΔN at BBN and at Recombination (ρ R / ρ R)REC − (ρ R / ρ R)BBN = 0. 07 ± 0. 14
CONCLUSIONS For ΔN ≈ 0, BBN (D, 3 He, 4 He) Agrees With The CMB + LSS (But , Lithium Is A Problem !) BBN + CMB + LSS Can Constrain Cosmology & Particle Physics
CHALLENGES • Why is the spread in D abundances so large ? • Why is 3 He/H uncorrelated with O/H and / or R ? • What (how big) are the systematic errors in YP ? Are there observing strategies to reduce them ? • What is the primordial abundance of 7 Li (6 Li) ? More data is needed !
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