Download - C. W. Kim KIAS The Johns Hopkins
C. W. Kim
KIAS
The Johns Hopkins
Neutrinos in Cosmology
October 27, 2008
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. (Charles Bennett in Nature in 2006) 1
Pauli to his friend Baade:1930
“Today I did something a physicist should never do. I predicted something which will never be observed experimentally…”
Neutrino : Pauli’particle
2
Fundamental Building Blocks
Quarks u c t
d s b (3 Colors )
Leptons
e μ τ
ν ν νe μ τ Neutrinos
3
4
Important Issues
1. Mass
2. Mixing
3. Number of flavors
4. CP violation
Oscillations
Lepto-genesis
5
From present evidences of oscillations from experiments measuring
atmospheric, solar, reactor and accelerator neutrinos
We know that flavour neutrino oscillations exist
Weak e.s.Mass e.s.
6
Neutrinos are mixed.
Production and detection
via Weak eigenstates
Propagation (Equ. Of motion)
via Mass eigenstates
νν
νµ
e
τ
=
U U Ue1 e2 e3
U U Uµ1 µ2 µ3
U U Uτ1 τ2 τ3
•
νν
ν2
1
3
(( They are massive. )
7
Mixing Matrix : Nuclear/Particle Physics
3
√
√2 2
2 22
sin θ13 ei δ
U≈
θ θθ ≈ ≈ < 35 4512 23 13
13o oo
Bi-large mixing with U =0, θ = θ , θ = θ = π /6e3 ATM23 12 SOL
√21
1
√2
√3 1
√22√21
√2
√3 1
2
8
• 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
Laboratory mass measurement experiments
e -33 eHe H
-2e2)Z(A, Z)(A,
9
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
11
If ∑ m j < 8 x 10 eV, the inverted hierarchy is ruled out !!
There are at least two neutrinos which are heavier than 8 X 10 eV .
-2
-3
No lower bound for the lightest neutrino !! 12
Tritium β
decay< 2.2 eV
2/1
22
iiei mUm
e
Neutrinoless
double betadecay<0.4-1.6 eV
i
ieiee mUm 2
<0.3-1.5 eV Cosmology
iim~
Absolute Mass Searches
13
T < eVT ~ MeV
Formation of Large Scale Structures
LSS
Cosmic Microwave Background
CMB
PrimordialNucleosynthesis
BBN
No flavour sensitivity Neff & mννevs νμ,τ Neff
Relic neutrinos influence several cosmological epochs
14
15
photons
neutrinos
cdm
baryons
Λ
Evolution of the background densities
m3=0.05 eV
m2=0.009 eV
m1≈ 0 eV
16
Number of Neutrino Flavors
17
Number of Neutrino flavors(in the Universe)
Decay of Z : data) (LEP 008.0984.2 N
N influences H :
Slow expansion ⇒ less He. Fast expansion ⇒ more He
+ 1.4- 1.2
4
4
(Particles such as sterile neutrinos are not included. m < 45 GeV).
BBN : N = 3.1 95% CL ( He + D data)
(Neutron life time = 14.76 minutes)
eff
eff
N = 3 ⇒ N = 3.046 (standard value)
(SM and neutrino oscillations : ν v.s. ν )
4
ν ν
e μ,τ
*
( Not relic!)*
18
N
inv
( Z → l l )
= 2.9840 ± 0.0082
This is valid for m < 45 GeV.
Particle Physics
Γ = Nν Γ( Z → ν ν )
= νinvΓ
ν
( Z → )ΓΓ ν ν
l l( Z → )
Z boson:
SM
19
Number of Neutrino flavors(in the Universe)
Decay of Z : data) (LEP 008.0984.2 N
N influences H :
Slow expansion ⇒ less He. Fast expansion ⇒ more He
+ 1.4- 1.2
4
4
(Particles such as sterile neutrinos are not included. m < 45 GeV).
BBN : N = 3.1 95% CL ( He + D data)
(Neutron life time = 14.76 minutes)
eff
eff
N = 3 ⇒ N = 3.046 (standard value)
(SM and neutrino oscillations : ν v.s. ν )
4
ν ν
e μ,τ
*
( Not relic!)*
20
T ( ) ~ 2 MeV : CC & NC
T ( ) ~ 3 MeV : NC only
No μ & τ in plasma
dec
dec νe
νμ ,τ
Neutrino Oscillations in plasma before decoupling
21
311
4
8
71
158
73
15
3/44
24
2
r TT
Ω Ω Ω Ω = 1 Λ m γ ν+ + +
*
To be determined22
1/3
411
T
T
ν
γ
23
311
4
8
71
158
73
15
3/44
24
2
r TT
Ω Ω Ω Ω = 1 Λ m γ ν+ + +
*
To be determined 24
Effect of Neff at later epochsNeff modifies the radiation content: Changes the epoch of matter-radiation equivalence
Galaxy Mass SpectrumAnisotropy Spectrum
25
WMAP 3b
26
↑
m
WMAP 5
27
Results: WMAP 5-year data
N eff = 4.4 + 1.5 (68%C.L.)_
1.9 < N < 7.8 (95%C.L.)eff
even after breaking degeneracy using
BAO, SN and HST28
Neutrino Mass Values
29
eV 93.2
mh Ω i
i2
ν
eV 15 m 0.3Ω Ω
eV 46 m 1 Ω eV 93.2
mhΩ
iimν
iiν
ii
2ν
MpceV 30
m 41
-1
ν
Neutrino Free Streaming
Φ
b, cdm
ν
30
30
mν
32
33
5
34
Parameter degeneracy: Neutrino mass and wIn cosmological models with more parameters the neutrino mass bounds can be relaxed.
Ex: quintessence-like dark energy with ρDE=w pDE
WMAP Coll, astro-ph/0603449
Λ
35
WMAP 5 year Data
WMAP -5
WMAP5 plus
BAO + SN
36
Neutrino Mass from Cosmology
1. CMB alone: Σm < 1.5 eV (95% CL)
2. With BAO and SN:
Σm < 0.61 eV (95% CL) with w = 1
Σm
ν
ν
ν < 0.66 eV (95% CL) without w = 1
( Remember that Σm and H are degenerate for CMB
but no degeneracy between w and Σ m )
ν o
3. To go beyond, we need SDSS, Lyman-α, … But bias, …
ν
37
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 Σ m j j
P(k)ΔP(k)
~ (1 eV
Σ m j j) (
ΩM h2 )0.10● _
Reduces small scale amplitude of Mass Fluctuations38
Horizon distance at matter = radiationEnters in matter dominated era
Enters in rad. Dominated era
Σ m = 1 eVi
39
13
40
Neutrino Mass from Cosmology
1. CMB alone: Σm < 1.5 eV (95% CL)
2. With BAO and SN:
Σm < 0.61 eV (95% CL) with w = 1
Σm
ν
ν
ν < 0.66 eV (95% CL) without w = 1
( Remember that Σm and H are degenerate for CMB but
no degeneracy between w and Σ m )ν o
3. To go beyond, we need SDSS, Lyman-α, sdFGRs … But galaxy bias, … :Non-linear effects
ν
Let’s pull it down to 0.08 eV
(Two ν are heavier than this value)
Star Gazer
m ν
WMAP
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 Ao
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 Ao
Layers of H Clouds ⇒ forest
Lyman-α forest spectrum from Q2139-4434 (z= 3.23)
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 Ao
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 ).
ΔP(k)/P(k) ~ -10 Ω / Ω : a factor of 2 suppression for Σm = 1 eV(7% of CDM)
νo
Mo
j
WMAP3
* m < 0.7 eV (95% CL)
*H and m degeneracy
νO
Unknown m ⇒ one of the largest systematic errors for estimating cosmological parameters from CMB
* m > 0.3 eV favors smaller Hubble constant.
ν
( Clean and Robustν
ν
*To improve the limit, need data other than WMAP !
SDSS, 2dFGRS, Lyman-α forest, Gravitational lensing,…
But inherent systematic errors need to be understood.
Conclusions
even with WMAP1 alone)