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MASSIVE NEUTRINOS AND COSMOLOGY

MASSIVE NEUTRINOS AND COSMOLOGY. ν. Sergio Pastor (IFIC). CuTAPP 2005, Ringberg Castle. Outline. Neutrinos as DM. Effect of neutrino mass on cosmological observables. Current bounds and future sensitivities. Neutrinos decoupled at T~MeV, keeping a

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MASSIVE NEUTRINOS AND COSMOLOGY

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  1. MASSIVE NEUTRINOS AND COSMOLOGY ν Sergio Pastor (IFIC) CuTAPP 2005, Ringberg Castle

  2. Outline Neutrinos as DM Effect of neutrino mass on cosmological observables Current bounds and future sensitivities

  3. Neutrinos decoupled at T~MeV, keeping a spectrum as that of a relativistic species • Number density • Energy density Massless Massive mν>>T The Cosmic Neutrino Background

  4. Primordial Nucleosynthesis BBN Cosmic Microwave Background CMB Formation of Large Scale Structures LSS T ~ MeV T < eV Non-instantaneous ν decoupling (including oscillations) νevsνμ,τ Neff No flavor sensitivityNeff & mν T.Pinto et al, in preparation Relic neutrinos influence several cosmological epochs

  5. 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 n F b, cdm

  6. 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 • HDM ruled out by structure formation CDM

  7. Neutrinos as Hot Dark Matter Massive Neutrinos can still be subdominant DM: limits on mν from Structure Formation (combined with other cosmological data) • Effect of Massive Neutrinos: suppression of Power at small scales

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

  9. 2dFGRS Galaxy Redshift Surveys SDSS ~ 1300 Mpc

  10. Field of density Fluctuations CMB experiments SDSS Galaxy Surveys Matter power spectrum is the Fourier transform of the two-point correlation function Power Spectrum of density fluctuations

  11. SDSS kmax Power spectrum of density fluctuations Bias b2(k)=Pg(k)/Pm(k) Non-linearity 2dFGRS

  12. W. Hu Neutrinos as Hot Dark Matter Massive Neutrinos can still be subdominant DM: limits on mν from Structure Formation (combined with other cosmological data) • Effect of Massive Neutrinos: suppression of Power at small scales

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

  14. Cosmological bounds on neutrino mass(es) A unique cosmological bound on mνDOES NOT exist ! • Different analyses have found upper bounds on neutrino masses, since they depend on • The assumed cosmological model: number of parameters (problem of parameter degeneracies) • The combination of cosmological data used

  15. Cosmological Parameters: example SDSS Coll, PRD 69 (2004) 103501

  16. Cosmological Data • CMB Temperature: WMAP plus data from other experiments at large multipoles (CBI, ACBAR, VSA…) • CMB Polarization: WMAP • Large Scale Structure: • * Galaxy Clustering (2dF,SDSS) • * Bias (Galaxy, …): Amplitude of the Matter P(k) (SDSS,σ8) • *Lyman-α forest: independent measurement of power on small scales • Priors on parameters from other data: SNIa (Ωm), HST (h), …

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

  18. Absolute mass scale searches

  19. Cosmological bounds on neutrino mass since 2003

  20. + HST, SNI-a [σ8] + Ly-α [bias] Neutrino masses in 3-neutrino schemes CMB + galaxy clustering Fig from Strumia & Vissani, hep-ph/0503246

  21. Global analysis:  oscillations + tritium  decay + 02 + Cosmology CMB + 2dF Fogli et al., PRD 70 (2004) 113003

  22. WMAP + Other CMB + 2dF + HST + SN-Ia 3 ν 4 ν Hannestad JCAP 0305 (2003) 004 (also Elgarøy & Lahav, JCAP 0304 (2003) 004) 95% CL 5 ν Hannestad The bound depends on the number of neutrinos • Example: in the 3+1 scenario, there are 4 neutrinos (including thermalized sterile) • Calculate the bounds with Nν > 3 Abazajian 2002, di Bari 2002

  23. (0 eV,3) (0 eV,3) (0 eV,7) (0 eV,7) (2.25 eV,7) (2.25 eV,7) Σmν and Neff degeneracy

  24. Analysis with Σmν and Neff free Previous + priors (HST + SN-Ia) WMAP + ACBAR + SDSS + 2dF 2σ upper bound on Σmν (eV) Hannestad & Raffelt, JCAP 0404 (2004) 008 Crotty, Lesgourgues & SP, PRD 69 (2004) 123007

  25. ThermalFD spectrum Distortion from  decay Cuoco, Lesgourgues, Mangano & SP, astro-ph/0502465 Non-thermal relic neutrinos  The spectrum could be distorted after neutrino decoupling Example: decay of a light scalar after BBN • CMB + LSS data still compatible with large deviations from a thermal neutrino spectrum (degeneracy NT distortion – Neff) • * Better expectations for future CMB + LSS data, but model degeneracy NT- Neff remains

  26. Sensitivity to With current best-fit values Future sensitivities to 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) • Fisher matrix analysis: expected sensitivities assuming a fiducial cosmological model • Forecast analysis for • WMAP and ΩΛ=0 models Hu et al, PRL 80 (1998) 5255 Recent update:Lesgourgues, SP & Perotto, PRD 70 (2004) 045016 Fiducial cosmological model: (Ωbh2 , Ωmh2 , h , ns , τ, Σmν) = (0.0245, 0.148, 0.70 , 0.98, 0.12,Σmν)

  27. Ideal CMB+40xSDSS Σm Σm PLANCK+SDSS 2 sensitivity Fiducial value • 0.21 eV (PLANCK+SDSS) • 0.13 eV (CMBpol+SDSS) Σm detectable at 2σ if larger than Lesgourgues, SP & Perotto, PRD 70 (2004) 045016

  28. galaxy weak lensing and CMB lensing Future sensitivities to Σmν: new ideas no bias uncertainty small scales in linear regime makes CMB sensitive to much smaller masses

  29. galaxy weak lensing and CMB lensing Future sensitivities to Σmν: new ideas sensitivity of future weak lensing survey (4000º)2 to mν σ(mν) ~ 0.1 eV Abazajian & Dodelson PRL 91 (2003) 041301 sensitivity of CMB (primary + lensing) to mν σ(mν) = 0.15 eV (Planck) σ(mν) = 0.044 eV (CMBpol) Kaplinghat, Knox & Song PRL 91 (2003) 241301

  30. KATRIN PLANCK + SDSS CMBpol + SDSS CMBpol (including CMB lensing) Neutrino masses in 3-neutrino schemes CMB + galaxy clustering + HST, SNI-a [σ8] + Ly-α [bias] Fig from Strumia & Vissani, hep-ph/0503246

  31. Conclusions Cosmological observables efficiently constrain some properties of (relic) neutrinos ν Bounds on the sum of neutrino masses from CMB + 2dFGRS or SDSS, and other cosmological data (best Σmν<0.42 eV, conservative Σmν<1 eV) Sub-eV sensitivity in the next future (0.1-0.2 eV and better)  Test degenerate mass region and eventually the IH case

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