1 / 50

Cosmological Aspects of Neutrino Physics (II)

Cosmological Aspects of Neutrino Physics (II). ν. Sergio Pastor (IFIC) 61st SUSSP St Andrews, August 2006. Cosmological Aspects of Neutrino Physics. 2nd lecture. Degenerate relic neutrinos (Neutrino asymmetries). Massive neutrinos as Dark Matter.

kairos
Download Presentation

Cosmological Aspects of Neutrino Physics (II)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Cosmological Aspects of Neutrino Physics (II) ν Sergio Pastor (IFIC) 61st SUSSP St Andrews, August 2006

  2. Cosmological Aspects of Neutrino Physics 2nd lecture Degenerate relic neutrinos (Neutrino asymmetries) Massive neutrinos as Dark Matter Effects of neutrino masses on cosmological observables

  3. Neutrinos coupled by weak interactions Decoupled neutrinos (Cosmic Neutrino Background) Primordial Nucleosynthesis T~MeV t~sec

  4. Distribution function of particle momenta in equilibrium Thermodynamical variables Equilibrium thermodynamics Particles in equilibrium when T are high and interactions effective T~1/a(t)

  5.    /T Neutrinos coupled by weak interactions Primordial Nucleosynthesis T~MeV t~sec

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

  7. Degenerate Big Bang 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

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

  9. Flavor neutrino oscillations in the Early Universe • Density matrix • Mixing matrix • Expansion of the Universe • Charged lepton background (2nd order contribution) • Collisions (damping) • Neutrino background: diagonal and off-diagonal potentials Dominant term: Synchronized Neutrino Oscillations

  10. Serpico & Raffelt 2005 Evolution of neutrino asymmetries BBN Dolgov et al 2002 Abazajian et al 2002 Wong 2002 Lunardini & Smirnov 2001 Effective flavor equilibrium (almost) established 

  11. Massive Neutrinos and Cosmology

  12. Primordial Nucleosynthesis BBN Cosmic Microwave Background CMB Formation of Large Scale Structures LSS T ~ MeV T < eV νevsνμ,τ Neff No flavour sensitivityNeff & mν Relic neutrinos influence several cosmological epochs

  13. We know that flavour neutrino oscillations exist From present evidences of oscillations from experiments measuring atmospheric, solar, reactor and accelerator neutrinos Evidence of Particle Physics beyond the Standard Model !

  14. Mixing Parameters... From present evidences of oscillations from experiments measuring atmospheric, solar, reactor and accelerator neutrinos Mixing matrix U Maltoni, Schwetz, Tórtola, Valle, NJP 6 (2004) 122

  15. Mixing Parameters... From present evidences of oscillations from experiments measuring atmospheric, solar, reactor and accelerator neutrinos Mixing matrix U Maltoni, Schwetz, Tórtola, Valle, NJP 6 (2004) 122

  16. Mixing Parameters... From present evidences of oscillations from experiments measuring atmospheric, solar, reactor and accelerator neutrinos Maltoni, Schwetz, Tórtola, Valle, NJP 6 (2004) 122

  17. eV eV solar m0 NORMAL INVERTED atm atm solar ... and neutrino masses Data on flavour oscillations do not fix the absolute scale of neutrino masses What is the value of m0 ?

  18. 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 • Future experiments (KATRIN) m(νe) ~ 0.2-0.3 eV • Neutrinoless double beta decay: if Majorana neutrinos • experiments with 76Ge and other isotopes: ImeeI < 0.4hN eV

  19. Cosmology < 0.3-2.0 eV Absolute mass scale searches

  20. photons neutrinos Λ cdm m3=0.05 eV baryons m2=0.009 eV m1≈ 0 eV Evolution of the background densities: 1 MeV → now Ωi= ρi/ρcrit

  21. Neutrinos decoupled at T~MeV, keeping a spectrum as that of a relativistic species Contribution to the energy density of the Universe At present 112 per flavour The Cosmic Neutrino Background • Number density • Energy density Massless Massive mν>>T

  22. Neutrino Free Streaming ν Φ b, cdm 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

  23. 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

  24. Neutrinos as Hot Dark Matter • Effect of Massive Neutrinos: suppression of Power at small scales RAFFELT

  25. Neutrinos as Hot Dark Matter • Effect of Massive Neutrinos: suppression of Power at small scales RAFFELT

  26. Neutrinos as Hot Dark Matter Massive Neutrinos can still be subdominant DM: limits on mν from Structure Formation (combined with other cosmological data)

  27. accélération décélération lente décélération rqpide accélération inflation radiation matière énergie noire Cosmological observables accélération acceleration décélération lente slow deceleration décélération rqpide fast deceleration accélération acceleration ? inflation RD (radiation domination) MD (matter domination) dark energy domination

  28. Field of density Fluctuations Matter power spectrum is the Fourier transform of the two-point correlation function Power Spectrum of density fluctuations

  29. 2dFGRS Galaxy Redshift Surveys SDSS ~ 1300 Mpc

  30. accélération décélération lente décélération rqpide accélération bias uncertainty 60 Mpc inflation radiation matière énergie noire linear non-linear δρ/ρ<1 δρ/ρ~ 1 matter power spectrum P(k)  Cosmological observables: LSS accélération acceleration décélération lente slow deceleration décélération rqpide fast deceleration accélération acceleration 0<z<0.2 ? inflation RD (radiation domination) MD (matter domination) dark energy domination Distribution of large-scale structures at low z galaxy redshift surveys

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

  32. accélération décélération lente décélération rqpide accélération various systematics inflation radiation matière énergie noire matter power spectrum P(k)  Cosmological observables : LSS accélération acceleration décélération lente slow deceleration décélération rqpide fast deceleration accélération acceleration ? 2<z<3 inflation RD (radiation domination) MD (matter domination) dark energy domination Distribution of large-scale structures at medium z Lyman-α forests in quasar spectra

  33. fν 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

  34. Structure formation after equality baryons and CDM experience gravitational clustering

  35. Structure formation after equality baryons and CDM experience gravitational clustering

  36. Structure formation after equality baryons and CDM experience gravitational clustering • growth ofdr/r (k,t)fixed by • « gravity vs. expansion » balance •  dr/ra

  37. Structure formation after equality baryons and CDM experience gravitational clustering neutrinos experience free-streaming with v = c or <p>/m

  38. Structure formation after equality baryon and CDM experience gravitational clustering baryons and CDM experience gravitational clustering neutrinos experience free-streaming with v = c or <p>/m neutrinos cannot cluster below a diffusion length l = ∫ v dt < ∫ c dt

  39. for (2p/k) <l , • free-streaming supresses growth of structures during MD •  dr/r a1-3/5 fnwith fn = rn /rm ≈ (Smn)/(15 eV) Structure formation after equality baryon and CDM experience gravitational clustering baryons and CDM experience gravitational clustering neutrinos experience free-streaming with v = c or <p>/m • neutrinos cannot cluster below a diffusion length l = ∫ v dt < ∫ c dt

  40. a dcdm Massless neutrinos db dn dg metric Structure formation after equality J.Lesgourgues & SP, Phys Rep 429 (2006) 307 [astro-ph/0603494]

  41. Structure formation after equality a dcdm db 1-3/5fn a Massive neutrinos fν=0.1 dn dg metric J.Lesgourgues & SP, Phys Rep 429 (2006) 307 [astro-ph/0603494]

  42. Effect of massive neutrinos on P(k) Observable signature of the total mass on P(k) : P(k) massive P(k) massless various fν Lesgourgues & SP, Phys. Rep. 429 (2006) 307

  43. accélération décélération lente décélération rqpide accélération inflation radiation matière énergie noire Cosmological observables: CMB accélération acceleration décélération lente slow deceleration décélération rqpide fast deceleration accélération acceleration ? z≈1100 inflation RD (radiation domination) MD (matter domination) dark energy domination Anisotropies of the Cosmic Microwave Background  photon power spectra CMB temperature/polarization anisotropies

  44. Map of CMBR temperature Fluctuations Multipole Expansion Angular Power Spectrum CMB TT DATA

  45. Map of CMBR temperature Fluctuations Multipole Expansion Angular Power Spectrum CMB TT DATA

  46. TT TE EE BB WMAP 3 CMB Polarization DATA

  47. Effect of massive neutrinos on the CMB spectra • Direct effect of sub-eV massive neutrinos on the evolution of the baryon-photon coupling is very small • Impact on CMB spectra is indirect: non-zero Ωνtoday implies a change in the spatial curvature or other Ωi . The background evolution is modified • Ex: in a flat universe, • keep ΩΛ+Ωcdm+Ωb+Ων=1 • constant

  48. Effect of massive neutrinos on the CMB spectra Problem with parameter degeneracies: change in other cosmological parameters can mimic the effect of nu masses

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

  50. End of 2nd lecture

More Related