Cosmological neutrinos after WMAP

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Cosmological neutrinos after WMAP

(and BBN after NACRE)

G. Mangano INFN, Naples IFAE, Lecce 2003

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SUMMARY

•Cosmological v: standard features

•Ωbh2 and Nv after WMAP

•Ωbh2 and Nv and BBN: an updated code after NACRE, LUNA,…(preliminary)

•Observations vs data for D, 4He and 7Li

•Neutrino asymmetry

•Cosmological bounds on v mass scale

•Conclusions

A. Cuoco, F. Iocco, G.M.,

G. Miele, O. Pisanti, P. Serpico

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At decoupling (T =2-4 MeV):

(almost) black body radiation

ν ν

ρ π

n m

T T T E

E f

v CMB v

30 11

4 4

7

1 ) / exp(

) 1 , (

4 3 2

/ 4

0

 

= 

= +

(4)

γ

γ

ρ ρ ρ

ρ

ρ

 

 

 

 + 

= +

+

=

v x v

R

N

3 / 4

11 4 8

1 7

Effective number of neutrinos

For 3 standard neutrinos Nv=3.04 Partial entropy transfer during e+-e- annihilation phase

f=fv(p,Tν)[1+δf(p)]

Tν 0.15% larger ρ(νe) 1% larger

ρ(νµ,τ) 0.5% larger

G.M., Miele, Pastor and Peloso 2002

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WMAP vs COBE

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WMAP achievements

Cosmological parameters: Ωxh2= ωx TE Polarization

Constraints on models for inflation: first evidence for scale dependence of spectral index

Test of gaussianity of fluctuations

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m m m

m a a

1 2

a 1 a

C l l

l l l

l

l l

=

= +

=

m

) , ( Y a )

,

∆(θ ϕ l m lm θ ϕ

l l

l

=

=

=

m 0

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Nv influences the matter-radiation equality

•WMAP + other CMB + 2dF + HST (+ SN-Ia)

3.7 2.0

eff 3.5

N = + Crotty, Lesgourgues & Pastor, astro-ph/0302337 FLAT MODEL

2.0 1.9

eff 4.1

N = + Pierpaoli, astro-ph/0302465 NON FLAT MODEL

95 c.l.

The large number of cosmological parameters does not allow for a more stringent limit

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Preliminary (Cuoco et al. in progress)

0 2 4 6 8

0 5×10-94 1×10-93 1.5 ×10-93 2×10-93 2.5 ×10-93

L(N

v

)

N

v

A rbi tr ar y no rm al iz at io n

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PLANCK experiment forecast

0ptimistic! Lopez et al, PRL 82 (1999) 3952

WMAP

PLANCK

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WMAP: the most accurate determination of baryons:

ω

b

=0.023≤0.001 (1σ)

CMB can do better than BBN: a new perspective:

standard BBN does work: prediction for light nuclei number fractions

OR

standard BBN inadequate

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0.02 0.022 0.024 0.026 0.028 0

5×10-94 1×10-93 1.5×10-93 2×10-93 2.5×10-93 3×10-93

Preliminary (Cuoco et al. in progress)

Arbitrary normalization

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b

h

2

, N

v

and BBN

bh2: increasing the baryon density leads to more 4He and less D

Nv: increasing the relativistic energy density speeds up the expansion and increases the 4He mass fraction

DATA

XD (2.78 +0.44-0.38) 10-5 (Kirkman et al. 2003) Ym(4He)

0.244 ≤ 0.002 (Izotov and Thuan ’98) 0.234 ≤ 0.003 (Olive and Steigman ’95) 0.239 ≤ 0.007 (conservative)

7Li

(1.73 ≤0.25) 10-10 (Bonifacio and Molaro ’97) (1.23+0.7-0.3) 10-10 (Ryan et al. 99)

SYSTEMATICS!!

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Precision cosmology requires precision calculations BBN code:

Detailed n-p ratio (radiative corrs.)

Most recent results on nuclear reactions Historical compilations:

Caughlan and Fowler ‘88

Smith, Kawano and Malaney ‘93

NACRE (Nuclear Astrophysics Compilation of REaction rates) catalogue + recent experiments (LUNA…)

Important to reduce the nuclear uncertainties

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Work in progress:

Update of all nuclear reaction rates relevant for BBN

Investigation of possible new processes till now neglected

Re-analysis of overall uncertainties on D, 4He and 7Li abundancies

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An example:

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NACRE

LUNA coll.

2002

BBN

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0.8 p(n, γ)D

2.6 D(p,γ)

3

He

21.5 D(D,p)

3

H

75 D(D,n)

3

He

σ

i2

/ σ

D2

(%) Reaction

σ

D2

/X

D

=6.5 % σ

4He2

/Y

m

=0.1 % σ

7Li2

/X

7Li

=20 %

Smith Kawano Malaney vs NACRE+New fit 10 –20 % difference for the rate

Reduction of the uncertainty: 10% 3%

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Y4=0.244 ±0.002

2 2.5 3 3.5 4

0.02 0.022 0.024 0.026

ω

b

N

v

CMB+D BBN (D+4He)

CMB+D

ωb=0.023±0.001 Nv=3±3

BBN

ωb=0.022±0.005 N=2.8 ±0.3

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2 2.5 3 3.5 4 0.018

0.02 0.022 0.024

Y4=0.234 ±0.003

ω

b

N

v

CMB+D

ωb=0.023±0.001 Nv=3±3

BBN

ωb=0.021±0.005 N=2.2 ±0.3

BBN (D+4He)

CMB+D

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Hannestad astro-ph/0303076

0.30.4

eff 2.6

N = +

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D (x105)

01 23 45 67 8

CMB (N=3.

04)

Q22 06-199

Q1009- 2956

HS0105-1619 Q0130-

4021

Q03 47-3819

Q03 47-3819

Q1243+

3047

PKS1937-1009

Average

D

-4 -3 -2 -1 0 1 2 3 4 5

D is presently in very good agreement with CMB

Unit: σtot = ( σexp2 + σth2 )1/2

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4He (Yp)

0,22 0,225 0,23 0,235 0,24 0,245 0,25

CMB (N=3.04)

Izotov &

Thuan '98

Olive &

Steigman '95

conservative

4He

-6 -5 -4 -3 -2 -1 0

Possible evidences for systematics ?

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7Li (x1010)

0 1 2 3 4 5 6 7

CMB (N=3.04) Bonifacio & Molaro '97

Ryan, Norris &

Beers '99

7Li

-8 -7 -6 -5 -4 -3 -2 -1 0

Significant

evidence for 7Li depletion

Dependence on metallicity

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2

2.5

3

3.5

4 0.02

0.021 0.022

0.023 0.024 3.5

4 4.5

5 5.5

2

2.5

3

3.5

4

7

Li/H versus ω

b

and N

v

(unit 10

-10

)

ω

b

N

v

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Degenerate neutrinos

Lepton – antilepton asymmetry From neutrality of the universe:

10

10

T

µ

e

No severe bounds on neutrino – antineutrino asymmetry.

What if µν ∫ 0 ?

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2 4

120 7 π T

ρ

ν

=

Non degenerate

 

 

= 

T T

ν

ν

µ ρ π 6

4

exp

2 Slightly degenerate

4

8

2

1 µ

ρ

ν

= π

Strongly degenerate

Notation: ξ

i

= µ

i

/T

Neutrino – antineutrino asymmetry!

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How neutrino chemical potentials affect BBN

1) chemical potentials contribute to Nν

2) a positive electron neutrino chemical potential (more neutrinos than

antineutrinos) favour n Ø p processes with respect to p Ø n processes.

From BBN alone: weak bounds

7 ....

15 7

3 30

4

4 2

2

 +

 

 +

+

= ∑

i

i

N

i

π ξ π

ξ

ν

Y

P

1 . 1 6

. 0

7 6

,

.

÷

≤ ξ

e

ξ

µ τ

Kang &

Steigman ‘92

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Hansen et al 2001 Hannestad 2003

4 . 2

22 . 0 01

.

0 ≤ ≤

,

− ξ

e

ξ

µ τ

Before WMAP After WMAP

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v oscillations (atmospheric + LMA solar like) mix neutrino asimmetries in

different flavors: more stringent bound

07 .

≤ 0

ξ

ν

Dolgov et al 2002

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LSS and cosmological bounds on neutrino masses

From bounds on total energy density

eV 46 m

1

eV

92.5 m h

i i

i i ν

ν 2 =

<

<

Massive

neutrinos free stream and

suppress small scale structures

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Tegmark’s Max homepage

www.hep.upenn.edu/~max/

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2dFGRS [Elgarøy et al] 2002

3 degenerate massive

neutrinos

WMAP+CBI+ACBAR+2dFGRS+Lyman α

Spergel et al astro-ph/0302209

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Conclusions

Precision era?

CMB provides the best extimate for baryon density

BBN: more careful analysis of nuclear network and big effort in experimental observations (systematics)

Neutrinos: 3, non degenerate is OK!

Future data (PLANCK, SDSS survey) may provide severe bounds on v masses:

v mass schemes, 2β0v decay (|<m>| <0.35 eV HM coll.) GENIUS |<m>|<0.01 eV

LSND

Σimi < 0.45 eV (WMAP+SDSS) Σimi < 0.12 eV (PLANCK+SDSS) m(ve) < 0.35 eV (KATRIN)

Hannestad astro-ph/0211106

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3 ν 4 ν

5 ν

Hannestad astro-ph/0303076

Elgarøy & Lahav, astro-ph/0303089)

figura

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