NEUTRINOS AND BBN ( & THE CMB) Gary Steigman (with thanks to J. P. Kneller & V. Simha) Departments of Physics and Astronomy Center for Cosmology and Astro-Particle Physics Ohio State University NO – VE, Venice, Italy, April 15 - 18, 2008

Primordial Nucleosynthesis Relic Photons (CMB) are free ~ 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 (CMB) are free

BBN (~ 20 Minutes) , The CMB (~ 400 kyr) & LSS (~ 10 Gyr) Provide Complementary Probes Of The Early Evolution Of The Universe Do predictions and observations of the baryon density (B) and the expansion rate (H) of the Universe agree at these different epochs? (G. S., Ann. Rev. Nucl. Part. Sci., 57 (2007) 463) V. Simha & G. S. astro-ph/0803.3465

 tBBN  4  24 min. The Early, Hot, Dense Universe Is A Cosmic Nuclear Reactor As the Universe expands and cools, BBN “begins” at T  70 keV (when n / p  1 / 7) Coulomb barriers and the absence of free neutrons terminate BBN at T  30 keV  tBBN  4  24 min.

Baryon Density Parameter B  nN / n ; 10   B = 274 Bh2 Note : Baryons  Nucleons B  nN / n ; 10   B = 274 Bh2 where : B  B / c ; c  critical density Hubble parameter : h  H0 / 100 km s-1 Mpc-1 h  0.7 ; H0-1 = 9.8 / h  14 Gyr

Evolution of Deuterium 10 More nucleons  less D

DEUTERIUM --- The Baryometer Of Choice 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 (    ) H  and D  are seen in Absorption, BUT … * H  and D  spectra are identical  H  Interlopers? * Unresolved velocity structure  Errors in N(H ) ?

D/H vs. Metallicity Low – Z / High – z QSOALS Deuterium Plateau ? Real variations, systematic differences, statistical uncertainties ?

D/H vs. Metallicity For Primordial D/H adopt the mean For the D/H error adopt the dispersion around the mean 105(D/H)P = 2.68 ± 0.27

D /H + SBBN  10 = 6.0 ± 0.4 SBBN

YP depends VERY WEAKLY on the nucleon abundance Almost all neutrons are incorporated in 4He n / p  1 / 7  YP  0.25 P 10 YP  4He Mass Fraction YP does depend on the competition between Γwk & H

The Expansion Rate (H  Hubble Parameter) provides a probe of Non-Standard Physics S2  (H/ H)2  /  1 + 7N / 43 S is parameterized by N    + N  and N  3 + N NOTE : G/ G  S2  1 + 7N / 43 4He is sensitive to H while D probes B

Extragalactic 4He Observations (H  Regions) As O/H  0, Y  0 SBBN Prediction : YP = 0.248 YP = 0.240 ± 0.006 ( Or : YP < 0.255 @ 2 σ )

BBN (D, 4He)  For N ≈ 2.4 ± 0.4 D & 4He Isoabundance Contours YP & yD  105 (D/H) 4.0 3.0 2.0 0.25 0.24 0.23 D & 4He Isoabundance Contours Kneller & Steigman (2004)

N vs. 10 From BBN (D & 4He) ( YP < 0.255 @ 2 σ ) BBN Constrains N N < 4 N > 1 V. Simha & G.S.

Lithium Observations in Galactic Halo Stars [Li]  12 + log(Li/H) Asplund et al. Ryan, Norris, Beers Lithium Plateau (?)

BBN and Primordial (Pop ) Lithium Li too low ? [Li]  12 + log(Li/H)  2.6 – 2.7 [Li]  12 + log(Li/H)  2.1 to be continued …

Even for N  3 Y + D  H  Li  H  4.0  0.7 x 10 10 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)

CBR

10 = 4.5, 6.1, 7.5 CMB Temperature Anisotropy Spectrum (T2 vs. ) Depends On The Baryon Density   10 = 4.5, 6.1, 7.5 V. Simha & G.S. The CMB is an early - Universe Baryometer

CMB  10 = 6.1 ± 0.2 10 Likelihood CMB

SBBN (20 min) & CMB (380 kyr) AGREE ! 10 Likelihoods CMB SBBN

CMB Temperature Anisotropy Spectrum Depends on the Radiation Density R (S or N)   N = 1, 3, 5 V. Simha & G.S. The CMB is an early - Universe Chronometer

CMB + LSS + HST Prior on H0 N vs. 10 CMB + LSS Constrains 10 V. Simha & G.S.

BBN (D & 4He) & CMB AGREE ! N vs. 10 CMB BBN V. Simha & G.S.

  Use the CMB + LSS to bound η10 and N Use BBN to predict YP , yDP , yLiP (solid black) Compare to the observed abundances (dashed)   ? V. Simha & G.S.

Some consequences of the good agreement between BBN and the CMB Entropy Conservation : N (CMB) / N (BBN) = 0.92 ± 0.07 Modified Radiation Density (late decay of massive particle) ρRCMB / ρRBBN = 1.07 +0.16 -0.13 Variation in the Gravitational Constant ? GBBN / G0 = 0.91 ± 0.07 ; GCMB / G0 = 0.99 ± 0.12

BBN + CMB Combined Fit N vs. 10 ( YP < 0.255 @ 2 σ ) V. Simha & G.S.

e Degeneracy (Non – Zero Lepton Number) Alternative to N  3 (S  1) e Degeneracy (Non – Zero Lepton Number) For e = e/kT  0 (more e than anti - e) n/p  exp ( m/kT  e )  n/p   YP  YP probes Lepton Asymmetry The CMB is insensitive to e

e Degeneracy (Non – Zero Lepton Number) For N = 3 : e = 0.035  0.026 YP & yD  105 (D/H) 4.0 4.0 3.0 2.0 & 10 = 5.9  0.4  0.23 0.24 0.25 But, [Li] = 2.6  0.7 Still ! Li depleted / diluted in Pop  stars ?

For BOTH N & e Free (using BBN + CMB) V. Simha & G.S.

For BOTH N & e Free (using BBN + CMB) V. Simha & G.S.

(The Theorist’s Mantra) More & Better Data Are Needed ! SUCCESS BBN (D, 3He, 4He) & the CMB Agree ! (Lithium ?) CHALLENGE (The Theorist’s Mantra) More & Better Data Are Needed !

BBN & The CMB Provide Complementary Probes Of The Early Universe Do predictions and observations of the baryon density agree at 20 minutes and at 400 kyr ? (Ann. Rev. Nucl. Part. Sci., 57 (2007) 463)

D, 3He, 7Li are potential BARYOMETERS BBN – Predicted Primordial Abundances 4He Mass Fraction BBN Abundances of D, 3He, 7Li are RATE (DENSITY) LIMITED 7Li 7Be D, 3He, 7Li are potential BARYOMETERS

Two pathways to mass - 7 10

SBBN 10 Likelihoods from D and 4He AGREE ? to be continued …

Summary : Baryon Density Determinations Depleted ? D & 3He agree with the CMB N < 3 ?

Observational Uncertainties Or New Physics? Depleted ? N < 3 ?