the universe is expanding

• 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 …

(n/p)eq BBN “Begins”

Decay

“Freeze – Out” ? Wrong!

Rates set by n

Statistical Errors

versus

Systematic Errors !

History of n measurements

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

(ηB not predicted (yet) by fundamental theory)

“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

10

More nucleons less D

Evolution of mass - 2

More nucleons less mass - 3

Two pathways to mass - 3

Two pathways to mass - 7

For η10 ≥ 3, more

nucleons more mass - 7

BBN abundances of masses – 6, 9 – 11

Abundances Are Very Small !

n / p 1 / 7 Y 2n / (n + p) 0.25

All / most neutrons are incorporated in 4He

Y is very weakly dependent on the nucleon abundance

Y 4He Mass Fraction

Y 4y/(1 + 4y)

y n(He)/n(H)

YP DOES depend on the competition between Γwk & H

BBN Abundances of D, 3He, 7Li

are RATE (DENSITY) LIMITED

D, 3He, 7Li are potential BARYOMETERS

SBBN – Predicted Primordial Abundances

7Li 7Be

4He Mass Fraction

Mostly H & 4He

• 4He (mass fraction Y) is NOT Rate Limited

• Expansion Rate Parameter : S H´/ H

S H´/ H (´ / )1/2 (1 + 7N / 43)1/2

where ´ + N and N 3 + N

• 4He IS n/p Limited Y is sensitive to the

EXPANSION RATE ( H 1/2 )

• S2 (H/ H)2 = G/ G 1 + 7N / 43

* S may be parameterized by N

The Expansion Rate Parameter (S)

Is A Probe Of Non-Standard Physics

• 4He is sensitive to S (N) ; D probes B

NOTE : G/ G = S2 1 + 7N / 43

N ( - ) / and N 3 + N

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 (S)

N = 2, 3, 4

4He is an early – Universe Chronometer

(S = 0.91, 1.00, 1.08)

Y 0.013 N 0.16 (S – 1)

Y vs. D / H

0.23

0.24

0.25

4.0 3.0 2.0

YP & yDP 105 (D/H)P

D & 4He Isoabundance Contours

Kneller & Steigman (2004)

Isoabundance Contours for 105(D/H)P & YP

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)

Kneller & Steigman (2004) & Steigman (2007)

Post – BBN Evolution

• As gas cycles through stars, D is only DESTROYED

• Stars burn H to 4He (and produce heavy elements)

4He INCREASES (along with CNO …)

• As gas cycles through stars, 3He is DESTROYED ,

PRODUCED and, some 3He SURVIVES

• Cosmic Rays and SOME Stars PRODUCE 7Li BUT,

7Li 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)

• H and D are observed in Absorption in High – z,

Low – Z, QSO Absorption Line Systems (QSOALS)

• (D/H) P is sensitive to the baryon density ( B

− )

“Measure” ( D / H ) P

Use BBN ( D / H ) P vs. 10 to constrain B

Infer B (B) at ~ 20 Min.

Predict (D/H)P

Ly - Absorption

Observing D in QSOALS

Observations of Deuterium In 7

High - Redshift, Low - Metallicity QSOALS

(Pettini et al. 2008)

log (D/H) vs. Oxygen Abundance

Where is the D – Plateau ?

log(105(D/H)P) = 0.45 ± 0.03

log (D/H) vs. Oxygen Abundance

10 (SBBN) = 5.81 ± 0.28

Caveat Emptor !

3He/H vs. O/H

No Clear Correlation With O/H

Stellar Produced ?

3He Consistent With SBBN

3He Observed In Galactic H Regions

(3He/H)P for B = B(SBBN + D)

Oxygen Gradient In The Galaxy

More gas cycled through stars

Less gas cycled through stars

3He Observed In Galactic HII Regions

SBBN

No clear correlation with R

Stellar Produced ?

More gas cycled through stars

Less gas cycled through stars

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)

Izotov & Thuan 2010

4He Observed in Low – Z Extragalactic H Regions

YP(IT10) = 0.2565 ± 0.0010 ± 0.0050

YP = 0.2565 ± 0.0060

Aver, Olive, Skillman 2010

Izotov & Thuan 2010

YP(IT10) = 0.2565 ± 0.0010 ± 0.0050

YP(AOS10) = 0.2573 ± 0.0028 ± ??

For SBBN (N = 3)

If : log(D/H)P = 0.45 ± 0.03

η10 = 5.81 ± 0.28 YP = 0.2482 ± 0.0005

YP(OBS) − YP(SBBN) = 0.0083 ± 0.0060

YP(OBS) = YP(SBBN) @ ~ 1.4 σ

But ! Lithium – 7 Is A Problem

[Li] ≡ 12 + log(Li/H)

[Li]SBBN = 2.66 ± 0.06

Where is the Lithium Plateau ?

Asplund et al. 2006

Boesgaard et al. 2005

Aoki et al. 2009

Lind et al. 2009

SBBN

Li/H vs. Fe/H

For BBN (with η10 & N (S) as free parameters)

BBN Abundances Are Functions of η10 & S

SBBN Predictions Agree With Observations Of

D, 3He, 4He, But NOT With 7Li

YP vs. (D/H)P for N = 2, 3, 4

N 3 ?

But, new (2010) analyses now claim

YP = 0.257 ± 0.006 !


YP & yD 105

(D/H)

4.0 3.0 2.0

0.24

0.25

0.26

YP & yD 105

(D/H)

0.26

0.25

0.24


4.0 3.0 2.0

log(D/H)P = 0.45 ± 0.03 & YP = 0.2565 ± 0.0060

η10 = 6.07 ± 0.34 & N = 3.62 ± 0.46

N = 3 @ ~ 1.3 σ

2.6 2.7 2.8

Lithium Isoabundance Contours

[Li]P = 12 + log(Li/H)

2.6 2.7 2.8

Even for N 3 , [Li]P > 2.6


Lithium – 7 Is STILL A Problem

[Li] ≡ 12 + log(Li/H)

[Li]BBN = 2.66 ± 0.07

BBN

[Li]OBS too low by ~ 0.5 – 0.6 dex

* 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 S (N) agree ?

• Is SBBN = SCMB = 1 ?

BBN (~ 3 Minutes) , The CMB (~ 400 kyr) ,

LSS (~ 10 Gyr) Provide Complementary Probes

Of The Early Evolution Of The Universe

CMBΔT

Δ

ΔTrms vs. Δ : Temperature Anisotropy Spectrum

CMB Temperature Anisotropy Spectrum

(T2 vs. ) Depends On The Baryon Density

The CMB provides an early - Universe Baryometer

10 = 4.5, 6.1, 7.5

V. Simha & G. S.

10 (CMB) = 6.190 ± 0.145 (Komatsu et al. 2010)

For N = 3 , is B (CMB) = B (SBBN) ?

10 (SBBN) = 5.81 ± 0.28

SBBN & CMB Agree Within ~ 1.2 σ


Depends On The Baryon Density

Likelihood Distributions For η10

SBBN CMB

At BBN, With η10 & N As Free Parameters

η10 (BBN) = 6.07 ± 0.34

At REC, With CMB (WMAP 7 Year Data) + LSS

η10 (REC) = 6.190 ± 0.145

η10 (BBN) & η10 (REC) Agree

η10 (REC) − η10 (BBN) = 0.12 ± 0.37

Likelihood Distributions For η10

BBN CMB


Depends on the Radiation Density R (S or N)

The CMB / LSS is an early - Universe Chronometer

N = 1, 3, 5

V. Simha & G. S.

At BBN, With η10 & N As Free Parameters

N(BBN) = 3.62 ± 0.46 N(BBN) = 3 @ ~ 1.3 σ

At REC, With CMB (WMAP 7 Year Data) + LSS

N(REC) = 4.30 ± 0.87 N(REC) = 3 @ ~ 1.5 σ

N(BBN) & N(REC) Agree

N (REC) − N (BBN) = 0.68 ± 0.98

BBN CMB

Likelihood Distributions For N

Likelihood Distributions For N

BBN CMB

N = 3

SBBN IS Consistent With D, 3He, 4He

And Agrees With The CMB + LSS + H0

CONCLUSION # 1

(But , Lithium Is A Problem !)

• Post – BBN Decay of Massive Particles ?

• Annihilation of Dark Matter Relics ?

• Li depleted / diluted in Pop Stars ?

Non - standard BBN (N ≠ 3, S ≠ 1) With

10 = 6.07 ± 0.34 & N = 3.62 ± 0.46

IS Consistent With D, 3He, & 4He

And With The CMB + LSS (But, 7Li ?)

CONCLUSION # 2

BBN + CMB Combined Can Constrain

Non-standard Cosmology & Particle Physics

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

Comparing BBN And The CMB

Variation of the Gravitational Constant

Between BBN, Recombination, and Today ?

G / G = S2 = 1 + 7N / 43

G (BBN) / G0 = 1.10 ± 0.08

G (REC) / G0 = 1.21 ± 0.14

“Extra” Radiation Density ?

Example : Late decay of a massive particle

Recall that : ρR / ρ R = S2 1 + 7N / 43

In the absence of the creation of new

radiation (via decay ?), S (BBN) = S (REC)

Comparing N at BBN and at Recombination

N (REC) − N (BBN) = 0.68 ± 0.98

For N ≈ 3, BBN (D, 3He, 4He)

Agrees With The CMB + LSS

CONCLUSIONS

BBN + CMB + LSS Constrain

Cosmology & Particle Physics

(But , Lithium Is A Problem !)

CHALLENGES

• Why is the spread in D abundances so large ?

• Why is 3He/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 7Li (6Li) ?

We (theorists) need more (better) data !

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

Lepton Asymmetry

YP probes e (Lepton Asymmetry)

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 + 5 e / 4

He 10 – 574 e / 4

Li 10 – 7 e / 4

Kneller & Steigman (2004) & Steigman (2007)


4.0 3.0 2.0

0.24

0.25

0.26

YP & yD 105

(D/H)

log(D/H)P = 0.45 ± 0.03 & YP = 0.2565 ± 0.0060

η10 = 5.82 ± 0.28 & e = − 0.036 ± 0.026

4.0 3.0 2.0

0.24

0.25

0.26


YP & yD 105

(D/H)

Likelihood Distribution for ξe

BBN

2.6 2.7 2.8

Lithium Isoabundance Contours[Li]P = 12 + log(Li/H)

2.82.6 2.7


Even for e 0 , [Li]P > 2.6

Lithium – 7 Is STILL A Problem

[Li] ≡ 12 + log(Li/H)

[Li]BBN = 2.66 ± 0.07

BBN

[Li]OBS too low by ~ 0.5 – 0.6 dex

BBN (D, 3He, 4He) Agrees With

The CMB + LSS (For N ≈ 3 & e ≈ 0)

CONCLUSIONS

BBN + CMB + LSS Combined Can Constrain

Non-Standard Cosmology & Particle Physics

(But, 7Li is a problem)

the universe is expanding

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