C. W. Kim KIAS The Johns Hopkins

1. Neutrinos in Cosmology C. W. Kim KIAS The Johns Hopkins October 27, 2008

2. It is truly remarkable that we should have come so far in determining, from the passive collection of a small fraction of the photons that chance to come our way, the properties of neutrinos better than nuclear/particle physics has ever attempted in many decades. (CharlesBennett in Naturein 2006) 1

3. Neutrino : Pauli’particle Pauli to his friend Baade:1930 “Today I did something a physicist should never do. I predicted something which will never be observed experimentally…” 2

4. Fundamental Building Blocks Quarks u c t d s b (3 Colors ) Leptons e μτ ννν Neutrinos μ τ e 3

5. 4

6. Important Issues • Mass • Mixing • Number of flavors • CP violation Oscillations Lepto-genesis 5

7. From present evidences of oscillations from experiments measuring atmospheric, solar, reactor and accelerator neutrinos Mass e.s. Weak e.s. We know that flavour neutrino oscillations exist 6

8. Neutrinos are mixed. ( They are massive. ) ( Production and detection via Weak eigenstates Propagation (Equ. Of motion) via Mass eigenstates ν U U U ν e e1 e2 e3 1 ν ν U U U = • µ 2 µ1 µ2 µ3 ν ν U U U τ 3 τ1 τ2 τ3 7

9. √ √ √ √ √ √ √ Mixing Matrix : Nuclear/Particle Physics i δ sin θ13 e 3 1 2 2 1 1 3 U ≈ 2 2 2 √ 2 2 1 1 3 2 2 2 √ 2 2 o o o θ θ θ ≈ 45 < 13 ≈ 35 23 12 13 Bi-large mixing with U =0, θ = θ , θ = θ = π/6 e3 23 12 SOL ATM 8

10. Laboratory mass measurement 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 with76Ge and other isotopes: ImeeI < 0.4hN eV 9

11. m ( ν ) < 0.17 Mev (95%CL) from π → μ + ν m ( ν ) < 18.2 MeV (95%CL) from τ → 3 π + 2 π + ν μ μ τ + τ Particle Physics 10

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13. -2 If ∑ m j < 8 x 10 eV, theinverted hierarchy is ruled out !! There are at least two neutrinos which are heavier than 8 X 10 eV . -3 No lower bound for the lightest neutrino !! 12

14. Cosmology <0.3-1.5 eV Absolute Mass Searches 13

15. 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 14

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17. photons neutrinos Λ cdm m3=0.05 eV baryons m2=0.009 eV m1≈ 0 eV Evolution of the background densities 16

18. Number of Neutrino Flavors 17

19. Number of Neutrino flavors(in the Universe) * ( Not relic!) Decay of Z : (Particles such as sterile neutrinos are not included. m < 45 GeV). + 1.4 4 BBN : N = 3.1 95% CL ( He + D data) eff - 1.2 N influences H : Slow expansion ⇒ less He. Fast expansion ⇒ more He eff 4 4 (Neutron life time = 14.76 minutes) * N = 3 ⇒ N = 3.046 (standard value) ν ν (SM and neutrino oscillations : νv.s.ν ) e μ,τ 18

20. Γ inv Particle Physics νν ) ( Z → Γ Γ = N Z boson: ν inv Γ ( Z → ) l l N = ν Γ νν ( Z → ) ( Z → l l ) SM = 2.9840 ± 0.0082 This is valid form < 45 GeV. ν 19

21. Number of Neutrino flavors(in the Universe) * ( Not relic!) Decay of Z : (Particles such as sterile neutrinos are not included. m < 45 GeV). + 1.4 4 BBN : N = 3.1 95% CL ( He + D data) eff - 1.2 N influences H : Slow expansion ⇒ less He. Fast expansion ⇒ more He eff 4 4 (Neutron life time = 14.76 minutes) * N = 3 ⇒ N = 3.046 (standard value) ν ν (SM and neutrino oscillations : νv.s.ν ) e μ,τ 20

22. T ( ) ~ 2 MeV : CC & NC T ( ) ~ 3 MeV : NC only No μ & τ in plasma ν dec e ν dec μ,τ Neutrino Oscillations in plasma before decoupling 21

23. * ΩΩΩΩ = 1 + + + γ ν Λ m To be determined 22

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25. * ΩΩΩΩ = 1 + + + γ ν Λ m To be determined 24

26. Effect of Neff at later epochs Neff modifies the radiation content: Changes the epoch of matter-radiation equivalence Anisotropy Spectrum Galaxy Mass Spectrum 25

27. b WMAP 3 26

28. WMAP 5 ↑ m 27

29. Results: WMAP 5-year data _ = 4.4 + 1.5 (68%C.L.) N eff eff 1.9 < N < 7.8 (95%C.L.) even after breaking degeneracy using BAO, SN and HST 28

30. Neutrino Mass Values 29

31. 30 Neutrino Free Streaming ν Φ b, cdm 30

32. m ν 31

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35. 5 34

36. Λ WMAP Coll, astro-ph/0603449 Parameter degeneracy: Neutrino mass and w In cosmological models with more parameters the neutrino mass bounds can be relaxed. Ex: quintessence-like dark energy with ρDE=w pDE 35

37. WMAP 5 year Data WMAP -5 WMAP5 plus BAO + SN 36

38. Neutrino Mass from Cosmology • CMB alone: Σm < 1.5 eV (95% CL) • With BAO and SN: • Σm < 0.61 eV (95% CL) with w = 1 • Σm ν ν < 0.66 eV (95% CL) without w = 1 ν (Remember that Σm and H are degenerate for CMB but no degeneracy between w and Σm) ν o ν 3.To go beyond, we need SDSS, Lyman-α, … But bias, … 37

39. Σ m j j Σ m j j Neutrinos as HDM ● As long as HDM is relativistic, HDM perturbations within the horizon are erased by “ Free – Streaming”. ● Free-streaming stops when HDM becomes non-relativistic at Zn-r . → If HDM dominates, top-down structure formation but, observation→ bottom-up. → limit on ΔP(k) 0.1 _ ● ~ ( ( ) ) 0 P(k) 1 eV ΩM h2 Reduces small scale amplitude of Mass Fluctuations 38

40. Horizon distance at matter = radiation Enters in matter dominated era Enters in rad. Dominated era Σ m = 1 eV i 39

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42. Neutrino Mass from Cosmology • CMB alone: Σm < 1.5 eV (95% CL) • With BAO and SN: • Σm < 0.61 eV (95% CL) with w = 1 • Σm ν ν < 0.66 eV (95% CL) without w = 1 ν (Remember that Σm and H are degenerate for CMB but no degeneracy between w and Σm) ν o ν 3.To go beyond, we need SDSS, Lyman-α, sdFGRs … But galaxy bias, … :Non-linear effects Let’s pull it down to 0.08 eV (Two ν are heavier than this value)

43. Star Gazer

44. m ν WMAP

46. Lyman-α forest data Absorption lines in the spectrum of distant quasars due to intermediate H clouds which absorb Lyman-α lines at λα = 1215.67 A o

47. Lyman-α forest data Absorption lines in the spectrum of distant quasars due to intermediate H clouds which absorb Lyman-α lines at λα = 1215.67 A o Layers of H Clouds ⇒ forest

48. Lyman-α forest spectrum from Q2139-4434 (z= 3.23)

49. Lyman-α forest data Absorption lines in the spectrum of distant quasars due to intermediate H clouds which absorb Lyman-α lines at λα = 1215.67 A o Layers of H Clouds ⇒ forest Absorption lines ⇒ Study of change of power spectrum of δρ/ρ for small λ But this is very difficult and model dependent ( bias ). o o ΔP(k)/P(k) ~ -10 Ω / Ω: afactor of 2suppression for Σm = 1 eV(7% of CDM) ν M j