•
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
(n/p) eq
“Freeze – Out” ? Wrong!
BBN “Begins”

Decay

 n
Statistical Errors versus
Systematic Errors !
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 t
BBN

4

24 min.

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


B
Note : Baryons

Nucleons

B
 n
N
/ n

;

10
   
B
= 274

B
2
Hubble Parameter : H = H(z)
In The Early Universe : H 2 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, 3 He, 4 He, 7 Li 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

Two pathways to mass - 7

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 4 He n / p

1 / 7

Y

2n / (n + p)

0.25
Y

4 He Mass Fraction
Y

4y/(1 + 4y) y
 n(He)/n(H)
Y
P
DOES depend on the competition between Γ wk
& H

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

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

• 4 He (mass fraction Y) is NOT Rate Limited
• 4 He 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


 and N


3 +

N


The Expansion Rate Parameter (S)
Is A Probe Of Non-Standard Physics
• S 2

(H

/ H) 2
= G
 
/ G
 
1 + 7

N

/ 43
* S may be parameterized by

N


N


(

-

) /

 and N


3 +

N

NOTE : G

/ G = S 2

1 + 7

N

/ 43
• 4 He 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, 3 He, 4 He, 7 Li are predicted as a function of two parameters :
* The baryon to photon ratio :

B
(SBBN)
* The effective number of neutrinos : N


4 He is 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)

Isoabundance Contours for 10 5 (D/H)
P
& Y
P
Y
P
& y
DP

10 5 (D/H)
P
4.0
2.0
3.0
0.25
0.24
0.23
D & 4 He Isoabundance Contours
Kneller & Steigman (2004)

Kneller & Steigman (2004) & Steigman (2007) y
DP

10 5 (D/H)
P
= 46.5 (1 ± 0.03)

D
-1.6
Y
P
= (0.2386 ± 0.0006) +

He
/ 625 y
7

10 10 ( 7 Li/H) = (1.0 ± 0.1) (

LI
) 2 / 8.5
where :

D
 
10
–
6 (S – 1)

He


Li


10
–
100 (S – 1)

10
–
3 (S – 1)

Post – BBN Evolution
• As gas cycles through stars, D is only DESTROYED
• As gas cycles through stars, 3 He is DESTROYED ,
PRODUCED and, some 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

Observing D in QSOALS
Ly -

Absorption

D/H vs. number of H atoms per cm 2
Observations of Deuterium In
7 High-Redshift, Low-Metallicity
QSO Absorption Line Systems
10 5 (D/H)
P
= 2.7 ± 0.2
(Weighted Mean of D/H)
( Weighted mean of log (D/H)

10 5 (D/H)
P
= 2.8 ± 0.2
)

log (D/H) vs. Oxygen Abundance log(10 5 (D/H)
P
) = 0.45 ± 0.03

(D /H) obs
+ BBN pred
 
10
= 6.0
± 0.3
BBN
V. Simha & G. S.

ΔT
Δ 
ΔT rms vs. Δ 
: Temperature Anisotropy Spectrum

CMB Temperature Anisotropy Spectrum
(

T 2 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 + LSS

10
 
10
= 6.1
± 0.2
Likelihood
CMB
V. Simha & G. S.

D/H vs. number of H atoms per cm 2
Observations of Deuterium In
7 High-Redshift, Low-Metallicity
QSO Absorption Line Systems
BBN + CMB/LSS

10 5 (D/H)
P
= 2.6 ± 0.1

BBN (~ 20 min) & CMB (~ 380 kyr) AGREE

10
Likelihoods
CMB
BBN
V. Simha & G. S.

3 He 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

3 He Observed In Galactic HII Regions
No clear correlation with R
Stellar Produced ?
SBBN

The 4 He 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
(Y
P
) ≈ 0.006, NOT < 0.001 !
Note : ΔY = ( ΔY / ΔZ ) Z << σ
(Y
P
)

4 He (Y
P
) Observed In Extragalactic H

Regions
As O/H

0, Y

0
SBBN Prediction : Y
P
≈ 0.249
K. Olive

SBBN

10
Likelihoods from D and 4 He
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 ?

Y
P vs. (D/H)
P for N

= 2 , 3 , 4
N


3 ?
But, new (2010) analyses now claim
Y
P
= 0.256 ± 0.006 !

A Non-Standard BBN Example (N
 eff < 3)
Late Decay of a
Massive Particle
&
Low Reheat Temp.
(T
R

MeV)

Relic Neutrinos Not
Fully (Re) Populated
Kawasaki, Kohri & Sugiyama
N
 eff < 3

Isoabundance Contours for 10 5 (D/H)
P
& Y
P
Y
P
& y
D

10 5 (D/H)
4.0
3.0
2.0
0.25
0.24
0.23
Kneller & Steigman (2004)

N
 vs.

10
From BBN (D &
4 He)
( Y
P
< 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
 
(S or N

)
N  = 1 , 3, 5
V. Simha & G. S.
The CMB / LSS is an early - Universe Chronometer

N

Is Degenerate With
 m h 2
The degeneracy can be broken
- partially - by H
0
(HST) and LSS
1 + z eq
=
 m
/

R
1 + z eq
≈
3200
V. Simha & G. S.

CMB + LSS + HST Prior on H
0
N
 vs.

10
CMB + LSS Constrain

10
V. Simha & G. S.

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

But, even for N

Y + D

H

3

Li

H

4.0

0.7 x 10

10 y
Li

10 10 (Li/H)
4.0
3.0
2.0
0.25
4.0
0.24
Li depleted / diluted in Pop
 stars ?
0.23
Kneller & Steigman (2004)

Alternative to N


3 (S

1)
 e
Degeneracy (Non – Zero Lepton Number)
Y
P
& y
D
 10 5 (D/H)
For
 e
=
 e
/kT

0
(more
 e than anti -
 e
)
4.0
3.0
0.23
2.0
n/p
 exp (
  m/kT
  e
)
 n/p
 
Y
P

0.24
0.25
Y
P probes
 e
Lepton Asymmetry
D & 4 He Isoabundance Contours
Kneller & Steigman (2004)

Kneller & Steigman (2004) & Steigman (2007) y
DP

10 5 (D/H)
P
= 46.5 (1 ± 0.03)

D
-1.6
Y
P
= (0.2386 ± 0.0006) +

He
/ 625 y
7

10 10 ( 7 Li/H) = (1.0 ± 0.1) (

LI
) 2 / 8.5
where :

D
 
10
+ 5
 e
/ 4

He


Li


10
– 574  e
/ 4

10
–
7
 e
/ 4

 e
Degeneracy (Non – Zero Lepton Number)
For N  = 3 :
 e
= 0.035

0.026
&

10
= 5.9

0.4

Y
P
& y
D

10 5 (D/H)
4.0
3.0
0.23
2.0
0.24
0.25
(V. Simha & G. S.)

BBN Constraints (D & 4 He) On
 e
For N  = 3
 e
= 0.035 ± 0.026

10
= 5.9 ± 0.3
V. Simha & G.S.

Even With Non - Zero
 e
Degeneracy,
The 7 Li Problem Persists
[Li] = 2.6

0.7 Still !
[Li] = 2.7

0.7 with
CFO 2008 results
4.0
y
Li

10 10 ( 7 Li/H)
3.0
4.0
0.23
2.0
0.24
Li depleted / diluted in Pop
 stars ?
0.25
Or, Late Decay of
(Charged) NLSP ?

BBN & The CBR Provide Complementary
Probes Of The Early Universe
Do predictions and observations of the baryon density parameter (

B
) and the expansion rate parameter (S or N

) agree at 20 minutes and at 400 kyr ?

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

Several consequences of the good agreement between BBN and CMB + LSS
Entropy Conservation : N  (CMB) / N  (BBN) = 0.92 ± 0.07
Modified Radiation Density (late decay of massive particle)
ρ
R
CMB / ρ
R
BBN = 1.07 +0.16
-0.13
Variation in the Gravitational Constant ?
G
BBN
/ G
0
= 0.91 ± 0.07 ; G
CMB
/ G
0
= 0.99 ± 0.12

BBN + CMB + LSS Combined Fit
N
 vs.

10
( Y
P
< 0.255 @ 2 σ )
N  = 2.5 ± 0.4

10
= 6.1 ± 0.1
V. Simha & G.S.

N

&
 e
BOTH FREE, BBN + CMB/LSS
Consistent with
 e
= 0 & N

= 3
 e
N  = 3.3 ± 0.7
= 0.056 ± 0.046
V. Simha & G.S.

BBN (D, 3 He, 4 He) Agrees With
The CMB + LSS (For N

≈ 3 &  e
≈
0 )
(But, 7 Li is a problem)
BBN + CMB + LSS Combined Can Constrain
Non-Standard Cosmology & Particle Physics