NEUTRINOS AND BBN (

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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
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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
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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
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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.
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• Baryon Density Parameter
• 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

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Evolution of Deuterium
?10
More nucleons ? less D
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DEUTERIUM --- The Baryometer Of Choice

• As the Universe evolves, D is only
  DESTROYED ?
• Anywhere, Anytime (D/H) t ? (D/H) P
• For Z ltlt 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 ?) ?

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D/H vs. Metallicity
Low Z / High z QSOALS
Deuterium Plateau ?
Real variations, systematic differences,
statistical uncertainties ?
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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
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D /H SBBN ? ?10 6.0 0.4
SBBN
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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
Gwk H
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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

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Extragalactic 4He Observations (H ?? Regions)
As O/H ? 0, Y ? 0
SBBN Prediction YP 0.248
YP 0.240 0.006 ( Or YP lt 0.255 _at_ 2
s )
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BBN (D, 4He) ?
For N? 2.4 0.4
YP yD ? 105 (D/H)
4.0
3.0
2.0
0.25
0.24
0.23
D 4He Isoabundance Contours
Kneller Steigman (2004)
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N? vs. ?10 From BBN (D 4He)
( YP lt 0.255 _at_ 2 s )
BBN Constrains N?
N? lt 4
N? gt 1
V. Simha G.S.
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Lithium Observations in Galactic Halo Stars
Li ? 12 log(Li/H)
Asplund et al.
Ryan, Norris, Beers
Lithium Plateau (?)
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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
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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)
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CBR
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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
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CMB ? ?10 6.1 0.2
?10 Likelihood
CMB
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SBBN (20 min) CMB (380 kyr) AGREE !
?10 Likelihoods
CMB
SBBN
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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
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CMB LSS HST Prior on H0
N? vs. ?10
CMB LSS Constrains ?10
V. Simha G.S.
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BBN (D 4He) CMB AGREE !
N? vs. ?10
CMB
BBN
V. Simha G.S.
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Use the CMB LSS to bound ?10 and N?
Use BBN to predict YP , yDP , yLiP
(solid black) Compare to the observed
abundances (dashed)
?
?
?
V. Simha G.S.
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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) ?RCMB / ?RBBN 1.07
0.16 -0.13
Variation in the Gravitational Constant
? GBBN / G0 0.91 0.07 GCMB / G0
0.99 0.12
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BBN CMB Combined Fit
N? vs. ?10
( YP lt 0.255 _at_ 2 s )
V. Simha G.S.
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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
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?e Degeneracy (Non Zero Lepton Number)
For N? 3 ?e 0.035 ? 0.026
YP yD ? 105 (D/H)
4.0
2.0
4.0
3.0

• ?10 5.9 ? 0.4 ?

0.23
0.24
0.25
But, Li 2.6 ? 0.7 Still !
Li depleted / diluted in Pop ?? stars ?
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For BOTH N? ?e Free (using BBN CMB)
?e 0.06 0.07
V. Simha G.S.
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For BOTH N? ?e Free (using BBN CMB)
V. Simha G.S.
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SUCCESS
BBN (D, 3He, 4He) the CMB Agree !
(Lithium ?)
CHALLENGE
(The Theorists Mantra) More Better Data
Are Needed !
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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)
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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
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Two pathways to mass - 7
?10
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SBBN ?10 Likelihoods from D and 4He
AGREE ?
to be continued
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Summary Baryon Density Determinations
Depleted ?
D 3He agree with the CMB
N? lt 3 ?
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Observational Uncertainties Or New Physics?
Depleted ?
N? lt 3 ?
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