Primordial Nucleosynthesis (BBN) and the radiation content of the early universe

11/58/58PASCOS 2010, ValenciaPASCOS 2010, Valencia

Primordial Nucleosynthesis Primordial Nucleosynthesis (BBN) (BBN)

and the radiation content of the and the radiation content of the

early universeearly universe

Gennaro MieleGennaro MieleUniversity of Naples “Federico II” and University of Naples “Federico II” and

INFN - Sezione di NapoliINFN - Sezione di Napoli

Sofia, 2011Sofia, 2011 11/27/27

22/27/27

A short review of BBN: A short review of BBN: recent data and theoretical statusrecent data and theoretical status

Sixty years after the seminal Sixty years after the seminal paper (Alpher, Bethe, paper (Alpher, Bethe, Gamow, 1948):Gamow, 1948):

•Theoretical (standard) framework well establishedTheoretical (standard) framework well established

• Increasingly precise data on Deuterium, Increasingly precise data on Deuterium, 44He(?), and He(?), and 77LiLi

• Increasingly precise data on nuclear process rates from Increasingly precise data on nuclear process rates from lab experiments at low energies (10 KeV – MeV)lab experiments at low energies (10 KeV – MeV)

• Baryon fraction measured very accurately by CMB and Baryon fraction measured very accurately by CMB and Deuterium, and they agree!!Deuterium, and they agree!!

COSMOLOGYCOSMOLOGY

ASTROPHYSICSASTROPHYSICS

FUNDAMENTALFUNDAMENTAL

MICROPHYSICSMICROPHYSICS

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BBN Input:BBN Input:- baryon density: - baryon density: = n = nBB/n/n ≈ 274 10≈ 274 10-10 -10 bbhh22

(Now from (Now from

CMB)CMB)- energy density in relativistic degrees of freedom- energy density in relativistic degrees of freedomhistorically described as “effective number of neutrinos”, historically described as “effective number of neutrinos”, but it can account but it can account partiallypartially for: for: 1) non instantaneous decoupling effects1) non instantaneous decoupling effects2) non standard 2) non standard -interactions, -interactions, -asymmetries-asymmetries3) extra relativistic degrees of freedom,exotic physics 3) extra relativistic degrees of freedom,exotic physics

BBN Output: XBBN Output: Xaa (nuclide abundances) (nuclide abundances)

3/4

0, 11

4

8

7

3(?)

N

NX

We can get information about Cosmological Neutrinos + extra We can get information about Cosmological Neutrinos + extra relativistic d.o.f. !relativistic d.o.f. !

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Solving numerically BBN dynamicsSolving numerically BBN dynamics

Neutrino decouplingNeutrino decoupling can be computed independently of nuclear abundances can be computed independently of nuclear abundances

1.1. Weak interactions freeze out at Weak interactions freeze out at T T ~~1 MeV1 MeV

2.2. Deuterium forms via Deuterium forms via p n p n D D

at T at T ~~ 0.1 MeV 0.1 MeV

3.3. Nuclear chainNuclear chain

1.1. Weak interactions freeze out at Weak interactions freeze out at T T ~~1 MeV1 MeV

2.2. Deuterium forms via Deuterium forms via p n p n D D

at T at T ~~ 0.1 MeV 0.1 MeV

3.3. Nuclear chainNuclear chain

Main uncertainty: neutron lifetimeMain uncertainty: neutron lifetimeττnn= 885.7 ± 0.8 sec (PDG)= 885.7 ± 0.8 sec (PDG)ττnn=878.5 ± 0.8 sec (Serebrov et al 2005)=878.5 ± 0.8 sec (Serebrov et al 2005)

44He mass fraction YHe mass fraction YPP linearly increases linearly increases with τwith τnn: 0.246 - 0.249: 0.246 - 0.249

Nico & Snow, Nico & Snow, Ann.Rev.Nucl.Part.Sci.55:27-69,2005Ann.Rev.Nucl.Part.Sci.55:27-69,2005

BBN accuracy IBBN accuracy I

Weak rates:Weak rates:• radiative corrections O(α)radiative corrections O(α)• finite nucleon mass O(T/Mfinite nucleon mass O(T/MNN))• plasma effects O(αT/mplasma effects O(αT/mee))• neutrino decoupling O(Gneutrino decoupling O(GFF

2 2 TT33 m mPlPl))

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z=T a e x Nveff

1.4 0.73% 0.52% 3.046

Small effect on Small effect on 44He mass fraction: He mass fraction: YYpp=2 10=2 10-4-4

Neutrino decoupling in detailsNeutrino decoupling in details • Non standard neutrino-electron interactions Non standard neutrino-electron interactions NPBB756:100 (2006)NPBB756:100 (2006)

• Including oscillation effects Including oscillation effects NPB729:221 (2005)NPB729:221 (2005)

• E.M. plasma effects E.M. plasma effects PLB534:8 (2002)PLB534:8 (2002)

• Neutrino chemical potentials Neutrino chemical potentials NPB590:539 (2000)NPB590:539 (2000)

but revisited after S.Pastor et al but revisited after S.Pastor et al PRL102:241302 (2009)PRL102:241302 (2009)

Neglecting Neglecting -asymmetries -asymmetries

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BBN accuracy IIBBN accuracy II

Nuclear rate benchmarks:Nuclear rate benchmarks:Caughlan and Fowler ‘88Caughlan and Fowler ‘88Smith, Kawano and Malaney ‘93Smith, Kawano and Malaney ‘93NACRENACRE

Recent efforts: reanalysis of the whole network Recent efforts: reanalysis of the whole network including recent experimental results (e.g. LUNA) and including recent experimental results (e.g. LUNA) and theoretical calculations (e.g. theoretical calculations (e.g. p n p n → → D D )). Main . Main improvements: underground measurements in low improvements: underground measurements in low energy range (100 KeV)energy range (100 KeV)


p n p n →→ D D

Pionless effective field Pionless effective field theory at Ntheory at N22LO and LO and NN44LO (Rupak)LO (Rupak)

error in 1-2% rangeerror in 1-2% range

D p D p →→ 33He He

error error reduced reduced from 13 to from 13 to 3%3%

LUNA 06LUNA 06Weizmann Inst. 04Weizmann Inst. 04

44He He 33He He →→ 77Be Be

results seem to results seem to worsen the worsen the 77Li Li problem problem


Nuclides consideredNuclides considered

PArthENoPEPublic Algorithm Evaluating Nucleosynthesis

of Primordial Elements

Comput.Phys.Commun.178:95Comput.Phys.Commun.178:956,20086,2008

http://parthenope.na.infn.it/http://parthenope.na.infn.it/

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Main problemMain problem

We cannot observe directly primordial abundances, since We cannot observe directly primordial abundances, since stars have changed the chemical composition of the universestars have changed the chemical composition of the universe

1)1) Observations in systems Observations in systems negligibly contaminated by stellar negligibly contaminated by stellar evolution;evolution;

2)2) Carefull account for galactic Carefull account for galactic chemical evolution.chemical evolution.

ASTROPHYSICAL OBSERVATIONSASTROPHYSICAL OBSERVATIONS

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The astrophysical environments which seem the most appropriate The astrophysical environments which seem the most appropriate are the hydrogen-rich clouds absorbing the light of background are the hydrogen-rich clouds absorbing the light of background QSO’s at high redshifts. QSO’s at high redshifts.

To apply the method one must require:To apply the method one must require:

(i)(i) neutral hydrogen column density in the range neutral hydrogen column density in the range 17 17 < < log[N(Hlog[N(HII))//cmcm-2-2] ] < < 21; 21;

(H(HI I regions are interstellar cloud made of neutral atomic hydrogen)regions are interstellar cloud made of neutral atomic hydrogen)

(ii)(ii) low metallicity [M/H] to reduce the chances of deuterium low metallicity [M/H] to reduce the chances of deuterium astration; astration;

(iii)(iii) low internal velocity dispersion of the atoms of the clouds, low internal velocity dispersion of the atoms of the clouds, allowing the isotope shift of only 81.6 km/s to be resolved.allowing the isotope shift of only 81.6 km/s to be resolved.

Only a few QASs pass the exam!Only a few QASs pass the exam!

DeuteriumDeuterium

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Our determinationOur determination 22H/H = (2.87H/H = (2.87 +0.22 +0.22-0.21-0.21) 10) 10-5-5

Iocco et al. PR472, 1 (2009)Iocco et al. PR472, 1 (2009)

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44HeHe

Observation of ionized gas (HeII Observation of ionized gas (HeII HeI HeI recombination lines in Hrecombination lines in HII II regions) regions)

in Blue Compact Galaxies (BCGs) in Blue Compact Galaxies (BCGs)

which are the least chemically evolved which are the least chemically evolved known galaxiesknown galaxies

YYP P in different galaxies plotted as in different galaxies plotted as

function of O and N abundances. function of O and N abundances.

Regression to “zero metallicity”Regression to “zero metallicity”

Nuclear stellar processes through successive generations of stars have burned Nuclear stellar processes through successive generations of stars have burned hydrogen into hydrogen into 44He and heavier elements, hence increasing the primordial He and heavier elements, hence increasing the primordial 44HeHe

Since the history of stellar processing is measured by Since the history of stellar processing is measured by metallicity metallicity ((ZZ) the ) the primordial value of primordial value of 44He mass fraction YHe mass fraction Ypp can be derived by extrapolating to O/H can be derived by extrapolating to O/H

and N/Hand N/H 00

Main sources of systematics:Main sources of systematics:i) interstellar reddeningi) interstellar reddeningii) temperature of cloudsii) temperature of cloudsiii) electron densityiii) electron densityPossible developments: using Possible developments: using more H linesmore H lines

Small statistical error but large systematicsSmall statistical error but large systematics

Recent analyses:Recent analyses:Izotov & Thuan 2010Izotov & Thuan 2010Aver, Olive & Skillmann 2010Aver, Olive & Skillmann 2010Aver, Olive & Skillmann Aver, Olive & Skillmann arXiv:1012.2385arXiv:1012.2385

1414/27/27

1515/27/27

All recent determinations are dominated by systematics. All recent determinations are dominated by systematics.

CMB anisotropies are sensitive to the reionization history, and CMB anisotropies are sensitive to the reionization history, and thus to fraction of baryons in the form of thus to fraction of baryons in the form of 44He. He.

Ony a marginal detection of a non-zero YOny a marginal detection of a non-zero Ypp, and even with , and even with

PLANCK the uncertainty will be larger than the present PLANCK the uncertainty will be larger than the present systematic spread of the astrophysical determinations.systematic spread of the astrophysical determinations.

• YYp p = 0.250 ± 0.003 = 0.250 ± 0.003 Iocco et al. PR472, 1 (2009)Iocco et al. PR472, 1 (2009)

• YYp p = 0.2565 ± 0.0010(stat)= 0.2565 ± 0.0010(stat) ± 0.0050(syst) ± 0.0050(syst) Izotov & Thuan 2010Izotov & Thuan 2010

• YYp p = 0.2561 ± 0.0108 = 0.2561 ± 0.0108 Aver et al. 2010Aver et al. 2010

• YYp p = 0.2573 ± 0.0033 = 0.2573 ± 0.0033 Aver et al. Aver et al. arXiv:1012.2385arXiv:1012.2385

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Likelihood analysisLikelihood analysis• Run a Run a BBNBBN code (PArthENoPE) to get Y code (PArthENoPE) to get YPP(N(N,,), X), XDD(N(N,,))

• Construct for each abundance the likelihood function:Construct for each abundance the likelihood function:

• Define a total likelihhod function L=LDefine a total likelihhod function L=L4He4He L LD D

• Plot the 68%, 95% and 99% cl contours in the (NPlot the 68%, 95% and 99% cl contours in the (N,,) plane) plane..

2

2

2

2

2

)(exp

),(2

)),((exp

),(2

1),(

exi

exi

thi

thi

exi

thi

i

Yx

N

NYxdx

NNL

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4He

2H

• Only Only 22H H ΩΩBBhh22 = 0.021 ± 0.001 = 0.021 ± 0.001

• Only Only 44He He ΩΩBBhh22 = 0.028 = 0.028+0.011+0.011-0.007-0.007

• WMAP 7-years WMAP 7-years ΩΩBBhh22 = 0.0226 ± 0.0005 = 0.0226 ± 0.0005

Compatible results at Compatible results at order 1.5 σorder 1.5 σ


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After marginalizationAfter marginalization

NN = 3.18 = 3.18 +0.22+0.22-0.21-0.21

(68% CL)(68% CL) 2.8 ≤ N2.8 ≤ N ≤ 3.6 (95% CL) ≤ 3.6 (95% CL)

BB h h22 =0.021 ± 0.001 (68% CL) =0.021 ± 0.001 (68% CL)Using YP from IT10

3.0 ≤ N3.0 ≤ N ≤ 4.5 (95% CL) ≤ 4.5 (95% CL)

Due to the largest value Due to the largest value of Yof YPP

Again Tension in BBN?Again Tension in BBN?


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Large neutrino chemical potentials are not Large neutrino chemical potentials are not forbidden. They affect BBN!forbidden. They affect BBN!

1) chemical potentials contribute to N1) chemical potentials contribute to N (if no extra (if no extra

d.o.f. and assuming T.E.)d.o.f. and assuming T.E.)

2) a positive electron neutrino chemical potential 2) a positive electron neutrino chemical potential ξξee

(more neutrinos than antineutrinos) favour (more neutrinos than antineutrinos) favour n np with respect to p p with respect to p n processes. n processes.

3) Neutrino oscillations mix3) Neutrino oscillations mix ξ ξee , ξ , ξxx . .They equilibrate if They equilibrate if θθ13 13

is not too smallis not too small

€

Nν = 3+30ξi

2

7π 2 +15ξ i

4

7π 4

⎛

⎝ ⎜

⎞

⎠ ⎟

i

∑YYPP

BBN and Neutrino Asymmetry: a leptometerBBN and Neutrino Asymmetry: a leptometer

YYPP

Dolgov et al 2002Dolgov et al 2002Iocco et al 2009Iocco et al 2009

2020/27/27

€

−0.021≤ ξα ≤ 0.005

€ €

€

ΔNν =30ξ i

2

7π 2 +15ξ i

4

7π 4

⎛

⎝ ⎜

⎞

⎠ ⎟

i

∑ ≤ 0.006

Even smaller than 0.046 due to non instantaneous decouplingEven smaller than 0.046 due to non instantaneous decoupling

However..However...v decouple from the thermal v decouple from the thermal bath, and scatterings & pair bath, and scatterings & pair processes may be inefficient to processes may be inefficient to re-adjust their distribution. re-adjust their distribution. Not a perfect FD (in general)!Not a perfect FD (in general)!

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We must follow neutrino We must follow neutrino decoupling during BBNdecoupling during BBN

For vanishing ϑ13

G. Mangano, G. M., S. Pastor, Pisanti, S. Sarikas G. Mangano, G. M., S. Pastor, Pisanti, S. Sarikas JCAP 1103 (2011) 035JCAP 1103 (2011) 035

2222/27/27

We evolve We evolve ρρνν starting from initial values of the total neutrino starting from initial values of the total neutrino

asymmetry asymmetry ηηνν and and ηηνeνe. The oscillation parameters are fixed . The oscillation parameters are fixed

at the fitted values apart of at the fitted values apart of θθ1313. .

Case for an intial Case for an intial ηηνν = −0.41 = −0.41, and , and ηηνeνeinin = =

0.820.82. The total neutrino asymmetry is . The total neutrino asymmetry is constant and equal to three times the constant and equal to three times the value shown (value shown (blue dotted lineblue dotted line).).

Same initial asymmetries. The Same initial asymmetries. The blue blue dotted line dotted line shows the case of shows the case of vanishing asymmetries vanishing asymmetries

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Spanning on the initial values of asymmetries and including Spanning on the initial values of asymmetries and including the neutrino dynamics in PArthENoPE we can performe a the neutrino dynamics in PArthENoPE we can performe a likelihood analysis for likelihood analysis for 22H and H and 44HeHe

The 95% C.L. contours from BBN analysis for θThe 95% C.L. contours from BBN analysis for θ1313 = 0 (left) and sin = 0 (left) and sin22 θ θ13 13 = 0.04 = 0.04

(right). The two contours correspond to the different choices for the primordial (right). The two contours correspond to the different choices for the primordial 4He abundances. The (red) dot-dashed line is the set of values which evolve 4He abundances. The (red) dot-dashed line is the set of values which evolve towards a vanishing final value of electron neutrino asymmetry. annihilation towards a vanishing final value of electron neutrino asymmetry. annihilation stage.stage.

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Deuterium removes the degeneracyDeuterium removes the degeneracy

Areas between the lines correspond to 95% C.L. regions Areas between the lines correspond to 95% C.L. regions singled out by the singled out by the 44He mass fraction (solid lines), and He mass fraction (solid lines), and Deuterium (dashed lines) Deuterium (dashed lines)

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The same but for final asymmetries: at the onset of BBNThe same but for final asymmetries: at the onset of BBN

For small values of θFor small values of θ1313, N, Neff eff can be as large as 3.4 still can be as large as 3.4 still

being compatible with BBN being compatible with BBN

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- Planck satellite will reach a sensitivity for NPlanck satellite will reach a sensitivity for Neffeff of the order of of the order of 0.40.4 at 2σ at 2σ- A detection of aA detection of a ΔNΔNeffeff = 0.4 – 0.5 = 0.4 – 0.5 could imply a large degeneracy but could imply a large degeneracy but

only for almost vanishing only for almost vanishing θθ1313, but in this case a measurement of such , but in this case a measurement of such

angle larger than almost angle larger than almost 0.030.03 would mean extra d.o.f. would mean extra d.o.f.- A detection of a A detection of a ΔNΔNeffeff > 0.5 would mean in anycase extra d.o.f. > 0.5 would mean in anycase extra d.o.f. - We have a robust limit from BBN: We have a robust limit from BBN: ΔNΔNeffeff ≤ 1.2 ≤ 1.2 at 2σ arXiv:1103:1261v1 at 2σ arXiv:1103:1261v1

[astro-ph.CO][astro-ph.CO]

ConclusionsConclusions

• BBN theory quite accurate, at BBN theory quite accurate, at

% level (or better) for main nuclides;% level (or better) for main nuclides;• Problem: systematics in Problem: systematics in 44He measurements, He measurements,

and Lithium still puzzling; new observational and Lithium still puzzling; new observational strategies ! strategies !

• BBN + CMB (PLANCK): a tool to constrain new BBN + CMB (PLANCK): a tool to constrain new physics.physics.

• Relevant the interplay with measurements in Relevant the interplay with measurements in lab which could fix better the range for θlab which could fix better the range for θ1313

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Primordial Nucleosynthesis (BBN) and the radiation content of the early universe