BBN, NEUTRINOS, AND THE CBR

Gary Steigman

(with J. P. Kneller & V. Simha)

Center for Cosmology and Astro-Particle Physics

Ohio State University

PPC 2007, TAMU, May 14 – 18, 2007

~ 0.1 s after the Big BangNeutrinos Decouple

~ 380 kyr after the Big BangRelic Photons (CBR) are free

~ 100 s after the Big BangPrimordial Nucleosynthesis

BBN (~ 20 Minutes) & The CBR (~ 400 kyr)

Provide Complementary Probes Of The

Early Evolution Of The Universe

Do predictions and observations of the baryon

density (10 (nB/nγ)0 = 274 Bh2 ) and

expansion rate (H) of the Universe agree

at these different epochs?

* Neutrinos Play Important Roles At Both Epochs

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 end BBN at T 30 keV

tBBN 4 24 min.

The Early, Hot, Dense Universe Is A

Cosmic Nuclear Reactor

BBN Abundances of D, 3He, 7Li

are RATE (Density) LIMITED

D, 3He, 7Li are potential BARYOMETERS

BBN – Predicted Primordial Abundances

7Li 7Be

4He Mass Fraction

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)

• 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) P is sensitive to the baryon density ( )

D/H vs. Metallicity

Deuterium Plateau ?

Real variations,systematic differences, statistical uncertainties ?

Low – Z / High – z QSOALS

105(D/H)P = 2.68 ± 0.27

For Primordial D/H adopt the mean

For the error adopt the dispersion around the mean

D/H vs. Metallicity

D + SBBN 10 = 6.0 ± 0.4

SBBN

CBR

CBR Temperature Anisotropy Spectrum

(T2 vs. ) Depends On The Baryon Density

The CBR is an early - Universe Baryometer

10 = 4.5, 6.1, 7.5

CBR constrains 10

V. Simha & G.S.

CBR 10 = 6.1 ± 0.2

V. Simha & G.S. (2007)

CBR

SBBN

CBR & SBBN (D) Agree !

• S H/ H (/)1/2 (1 + 7N / 43)1/2

The Expansion Rate (H Hubble Parameter)

provides a probe of Non-Standard Physics

• 4He is sensitive to S while D probes

+ N and N 3 + N

4He provides a Chronometer

D provides a Baryometer

SBBN Prediction

As O/H 0, Y 0

Do SBBN Predictions of D and 4He Agree ?

Likelihoods (SBBN) from D and 4He

AGREE ?

0.23

0.24

0.25

4.0 3.0 2.0

YP & yD 105 (D/H)

D & 4He Isoabundance Contours

Kneller & Steigman (2004)

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)

NSBBN

NSBBN (D & 4He) 10 = 5.7 ± 0.4

BBN (20 min) & CBR (380 kyr) AGREE on 10

NSBBN

NSBBN (D & 4He) N = 2.4 ± 0.4

CBR Temperature Anisotropy Spectrum

Depends on the Radiation Density R (S or N)

The CBR is an early - Universe Chronometer

N = 1, 3, 5

V. Simha & G.S.

CBR constrains N (S)

CBR

N = 2.3 (1.2 ≤ N ≤ 4.4 @ 68 %)

CBR

BBN

BBN (20 min) & CBR (380 kyr) AGREE on N

BBN (D & 4He)

V. Simha & G.S.

BBN Constrains N

N < 4

N > 1

CBR

V. Simha & G.S.

CBR Constrains 10

BBN (D & 4He) & CBR AGREE !

V. Simha & G.S.

Lithium ( “Spite” ) Plateau (?)

[Li] 12 + log(Li/H) 2.1

[Li] 12 + log(Li/H) 2.6 – 2.7

Li too low ?

BBN and Primordial (Pop ) Lithium

4.0 3.0 2.0

0.25

0.24

0.23

yLi 1010 (Li/H)

4.0

Even for N 3

Y + D H

Li H 4.0 0.7 x 10 10

log (Li) 2.6 0.1

(vs. log (Li)obs 2.2)

Li depleted / diluted

in Pop stars ?

Summary : Baryon Density Determinations

N < 3 ?

Depleted ?

D & 3He agree with the CBR

Summary : N Determinations

95% Ranges

BBN (D & 4He) and the CBR Agree !

(The Theorist’s Mantra)

More & Better Data Are Needed !

SUCCESS

CHALLENGE

(Lithium ?)