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RELIC NEUTRINOS: NEUTRINO PROPERTIES FROM COSMOLOGY

RELIC NEUTRINOS: NEUTRINO PROPERTIES FROM COSMOLOGY. ν. Sergio Pastor (IFIC). RELIC NEUTRINOS: OUTLINE. Standard neutrinos. Extra radiation and Neutrino asymmetries. Massive neutrinos. RELIC NEUTRINOS. Standard neutrinos. Extra radiation and Neutrino asymmetries. Massive neutrinos.

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RELIC NEUTRINOS: NEUTRINO PROPERTIES FROM COSMOLOGY

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  1. RELIC NEUTRINOS: NEUTRINO PROPERTIES FROM COSMOLOGY ν Sergio Pastor (IFIC)

  2. RELIC NEUTRINOS: OUTLINE Standard neutrinos Extra radiation and Neutrino asymmetries Massive neutrinos

  3. RELIC NEUTRINOS Standard neutrinos Extra radiation and Neutrino asymmetries Massive neutrinos

  4. Standard Relic Neutrinos Neutrinos in equilibrium fν(p,T)=fFD(p,T)

  5. Neutrinos in Equilibrium 1 MeV  T mμ Tν= Te = Tγ

  6. Standard Relic Neutrinos Neutrinos in equilibrium fν(p,T)=fFD(p,T)

  7. Neutrino decoupling

  8. Neutrino decoupling Tdec(νe) ~ 2.3 MeV Tdec(νμ,τ) ~ 3.5 MeV Decoupled Neutrinos fν(p)=fFD(p,Tν)

  9. Neutrino and Photon temperatures At T~me, electron-positron pairs annihilate heating photons but not the decoupled neutrinos Decoupled neutrinos stream freely until non-relativistic

  10. Neutrinos after decoupling • Number density • Energy density Massless Massive mν>>T

  11. Neutrinos and Cosmology Neutrinos influence several cosmological scenarios

  12. RELIC NEUTRINOS Standard neutrinos Extra radiation and Neutrino asymmetries Massive neutrinos

  13. Relativistic particles in the Universe At T<<me, the radiation content of the Universe is Effective number of relativistic neutrino species Traditional parametrization of the energy density stored in relativistic particles Neff is not exactly 3 for standard neutrinos (if mν<<T)

  14. Non-instantaneous neutrino decoupling At T~me, e+e- pairs annihilate heating photons But, since Tdec(νe) ~ me, neutrinos slightly share a small part of the entropy release

  15. Non-instantaneous neutrino decoupling fν=fFD(p,Tν)[1+δf(p)] Tν 0.15% larger ρ(νe) 1% larger ρ(νμ,τ) 0.5% larger Non-instantaneous decoupling + QED corrections to e.m. plasma Neff=3.0395 But, since Tdec(νe) ~ me, neutrinos slightly share a small part of the entropy release Mangano et al 2002

  16. Extra relativistic particles • Extra radiation can be: • scalars, pseudoscalars, sterile neutrinos (totally or partially • thermalized, bulk), neutrinos in very low-energy reheating • scenarios, relativistic decay products of heavy particles… • Particular case: relic neutrino asymmetries Constraints from BBN and from CMB+LSS

  17. BBN: Creation of light elements Produced elements: D, 3He, 4He, 7Li and small abundances of others Standard BBN: the baryon density is the sole parameter

  18. BBN: Predictions vs Observations After WMAP ΩBh2=0.023±0.001 Fields & Sarkar PDG 2002

  19. Effect of Neff on BBN Neff fixes the expansion rate during BBN 3.4 3.2 3.0 (Neff)>0 4He Burles, Nollett & Turner 1999

  20. BBN: allowed ranges for Neff Hannestad astro-ph/0303076 Not significantly different from previous analyses Hannestad astro-ph/0303076 Lisi et al 1999, Esposito et al 2000, Burles et al 2001, Cyburt et al 2002… Hannestad astro-ph/0303076 Cyburt et al, astro-ph/0302431

  21. CMB DATA: FIRST YEAR WMAP vs COBE

  22. CMB DATA: INCREASING PRECISION Map of CMBR temperature Fluctuations Multipole Expansion Angular Power Spectrum

  23. CMB DATA: INCREASING PRECISION Degrees (θ) 10 1 0.1

  24. CMB DATA: FIRST YEAR OF WMAP Degrees (θ) 10 1 0.1

  25. Effect of Neff on CMB • Neff modifies the radiation content: • Changes the epoch of matter-radiation equivalence

  26. CMB+LSS: allowed ranges for Neff Problem: parameter degeneracies • Set of parameters: ( Ωbh2 , Ωcdmh2 , h , ns , A , b , Neff ) • DATA: WMAP + other CMB + 2dF + HST (+ SN-Ia) • Upper bound on h important to fix upper limit on Neff • Flat Models • Non-flat Models 95% CL Crotty, Lesgourgues & SP, astro-ph/0302337 Pierpaoli astro-ph/0302465 95% CL

  27. Future bounds on Neff • Next CMB data from WMAP and PLANCK (other CMB experiments on large l’s) temperature and polarization spectra • Forecast analysis in ΩΛ=0 models Lopez et al, PRL 82 (1999) 3952 PLANCK Recent analysis: Larger errors Bowen et al 2002 WMAP ΔNeff ~ 3 (WMAP) ΔNeff ~ 0.2 (Planck)

  28. Degenerate Relic Neutrinos    /T Neutrinos in equilibrium fν(p,T)=fFD(p,T)

  29. Relic neutrino asymmetries Fermi-Dirac spectrum with temperature T and chemical potential  Raffelt More radiation

  30. Degenerate Nucleosynthesis If 0 , for any flavor ()>(0) 4He Plus thedirect effecton np if(e)0 e>0  4He Pairs (e,N)that produce the same observed abundances forlarger B Kang & Steigman 1992

  31. Combined bounds BBN & CMB-LSS Degeneracy direction (arbitrary ξe) Hansen et al 2001 Hannestad 2003 In the presence of flavor oscillations ?

  32. Flavor neutrino oscillations in the Early Universe • Density matrix • Mixing matrix • Expansion of the Universe • Charged lepton background (finite T contribution) • Collisions (damping) • Neutrino background: diagonal and off-diagonal potentials Dominant term: Synchronized Neutrino Oscillations

  33. Evolution in ATM + solar LMA (13=0) BBN Effective flavor equilibrium (almost) established  Dolgov et al 2002

  34. Evolution in ATM + solar LOW (13=0) BBN Synchronized neutrino oscillations Small conversion before the onset of BBN

  35. RELIC NEUTRINOS Standard neutrinos Extra radiation and Neutrino asymmetries Massive neutrinos

  36. Neutrinos as Dark Matter • Neutrinos are natural DM candidates • They stream freely until non-relativistic (collisionless phase mixing) Neutrinos are HOT Dark Matter • First structures to be formed when Universe became matter -dominated • Ruled out by structure formation CDM Neutrino Free Streaming

  37. Neutrinos as Dark Matter • Neutrinos are natural DM candidates • They stream freely until non-relativistic (collisionless phase mixing) Neutrinos are HOT Dark Matter • First structures to be formed when Universe became matter -dominated • Ruled out by structure formation CDM

  38. Power Spectrum of density fluctuations Massive Neutrinos can still be subdominant DM: limits on mν from Structure Formation CMB experiments Galaxy Surveys

  39. Neutrinos as Hot Dark Matter • Effect of Massive Neutrinos: suppression of Power at small scales W. Hu

  40. Effect of massive neutrinos on the CMB and Matter Power Spectra Max Tegmark’s homepage www.hep.upenn.edu/~max/

  41. 2dFGRS Galaxy Survey

  42. 2dFGRS Galaxy Survey ~ 1300 Mpc

  43. Power spectrum of density fluctuations from 2dF Non-linearity Bias b2(k)=Pg(k)/Pm(k) 2dFGRS [Elgarøy et al] 2002

  44. Neutrino mass in 3-neutrino schemes From present evidences of atmospheric and solar neutrino oscillations eV eV solar m0 atm atm solar 3 degenerate massive neutrinos Σmν = 3m0`

  45. Direct laboratory bounds on mν Searching for non-zero neutrino mass in laboratory experiments • Tritium beta decay: measurements of endpoint energy • m(νe) < 2.2 eV (95% CL) Mainz-Troitsk • Future experiments (KATRIN) m(νe) ~ 0.3 eV • Neutrinoless double beta decay: if Majorana neutrinos • 76Ge experiments: ImeeI < 0.35 eV

  46. Bound on mν after first year WMAP data 3 degenerate massive neutrinos Σmν < 0.71 eV Ωνh2 < 0.0076 95% CL m0 < 0.23 eV WMAP+CBI+ACBAR+2dFGRS+Lyman α Spergel et al astro-ph/0302209

  47. Is the 3+1 LSND scenario ruled out ? Pierce & Murayama hep-ph/0302131 Strumia hep-ph/0201134 (v4) Giunti hep-ph/0302173 3+1 solution strongly disfavored Σmν < 0.71 eV Ωνh2 < 0.0076 More conservative Σmν < 1.01 eV Hannestad astro-ph/0303076 Elgarøy & Lahav astro-ph/0303089 Small marginally allowed region

  48. Real bound on the 3+1 LSND scenario • Take into account the number of neutrino species • 3+1 scenario: 4 neutrinos (including thermalized sterile) • Calculate the bounds with Nν > 3 Abazajian 2002, di Bari 2002 WMAP + Other CMB + 2dF + HST + SN-Ia 3 ν 4 ν Hannestad astro-ph/0303076 (also Elgarøy & Lahav, astro-ph/0303089) 95% CL 5 ν 1 massive + 3 massless case not yet considered Crotty, Lesgourgues & SP, in preparation Hannestad

  49. Future bounds on Σmν • Next CMB data from WMAP and PLANCK (other CMB experiments on large l’s) temperature and polarization spectra • SDSS galaxy survey: 106 galaxies (250,000 for 2dF) • Forecast analysis in WMAP and ΩΛ=0 models Hu et al, PRL 80 (1998) 5255 With current best-fit values

  50. Future bounds on Σmν • Updated analysis: Hannestad astro-ph/0211106 • Σm detectable at 2σ if larger than • With a galaxy survey ~10 times SDSS 0.03-0.06 eV • From weak gravitational lensing: sensitive to both dark energy and neutrino mass. Future ~ 0.1 eV • 0.45 eV (WMAP+SDSS) • 0.12 eV (PLANCK+SDSS) Abazajian and Dodelson astro-ph/0212216

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