Cosmological Aspects of Neutrino Physics (II) - PowerPoint PPT Presentation

About This Presentation
Title:

Cosmological Aspects of Neutrino Physics (II)

Description:

Degenerate relic neutrinos (Neutrino asymmetries) ... BOSE. NON REL. RELATIVISTIC. VARIABLE. T~MeV. t~sec. Primordial. Nucleosynthesis. Neutrinos coupled ... – PowerPoint PPT presentation

Number of Views:26
Avg rating:3.0/5.0
Slides: 51
Provided by: sergio122
Category:

less

Transcript and Presenter's Notes

Title: Cosmological Aspects of Neutrino Physics (II)


1
Cosmological Aspects of Neutrino Physics (II)
?
  • 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
TMeV tsec
4
Equilibrium thermodynamics
Distribution function of particle momenta in
equilibrium Thermodynamical variables
VARIABLE RELATIVISTIC RELATIVISTIC NON REL.
VARIABLE BOSE FERMI NON REL.
Particles in equilibrium when T are high and
interactions effective
T1/a(t)
5
Neutrinos coupled by weak interactions
Primordial Nucleosynthesis
TMeV tsec
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
?(??)gt?(0) ? ? 4He
Plus the direct effect on n?p if ??(?e)?0
?egt0 ? ? 4He
Pairs ?(?e,?N?) that produce the same observed
abundances for larger ?B
Kang Steigman 1992
8
Combined bounds BBN CMB-LSS
Degeneracy direction (arbitrary ?e)
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
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
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
... 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 m?
Searching for non-zero neutrino mass in
laboratory experiments
  • Tritium beta decay measurements of endpoint
    energy
  • m(?e) lt 2.2 eV (95 CL) Mainz
  • Future experiments (KATRIN) m(?e) 0.2-0.3 eV
  • Neutrinoless double beta decay if Majorana
    neutrinos
  • experiments with 76Ge and other isotopes ImeeI
    lt 0.4hN eV

19
Absolute mass scale searches
Tritium ß decay lt 2.2 eV
Neutrinoless double beta decay lt 0.4-1.6 eV
20
Evolution of the background densities 1 MeV ? now
Oi ?i/?crit
21
The Cosmic Neutrino Background
  • Number density
  • Energy density

Massless
Massive m?gtgtT
22
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 m? from Structure Formation (combined
with other cosmological data)
27
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
Power Spectrum of density fluctuations
29
Galaxy Redshift Surveys
SDSS
1300 Mpc
30
Cosmological observables LSS
accélération
acceleration
décélération lente
slow deceleration
décélération rqpide
fast deceleration
accélération
acceleration
0ltzlt0.2
?
inflation
RD (radiation domination)
MD (matter domination)
dark energy domination
Distribution of large-scale structures at low z
galaxy redshift surveys
31
Power spectrum of density fluctuations
Bias b2(k)Pg(k)/Pm(k)
32
Cosmological observables LSS
accélération
acceleration
décélération lente
slow deceleration
décélération rqpide
fast deceleration
accélération
acceleration
?
2ltzlt3
inflation
RD (radiation domination)
MD (matter domination)
dark energy domination
Distribution of large-scale structures at
medium z
Lyman-a forests in quasar spectra
33
Neutrinos as Hot Dark Matter
Massive Neutrinos can still be subdominant DM
limits on m? 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 clusterin
g
35
Structure formation after equality
baryons and CDM experience gravitational clusterin
g
36
Structure formation after equality
baryons and CDM experience gravitational clusterin
g
growth of dr/r (k,t) fixed by  gravity vs.
expansion  balance ? dr/r ? a
37
Structure formation after equality
baryons and CDM experience gravitational clusterin
g
neutrinos experience free-streaming with v c
or ltpgt/m
38
Structure formation after equality
baryon and CDM experience gravitational clustering
baryons and CDM experience gravitational clusterin
g
neutrinos experience free-streaming with v c
or ltpgt/m
  • neutrinos cannot cluster below a diffusion
    length
  • l ? v dt lt ? c dt

39
Structure formation after equality
baryon and CDM experience gravitational clustering
baryons and CDM experience gravitational clusterin
g
neutrinos experience free-streaming with v c
or ltpgt/m
  • neutrinos cannot cluster below a diffusion
    length
  • l ? v dt lt ? c dt

40
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 f?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 f?
Lesgourgues SP, Phys. Rep. 429 (2006)
307
43
Cosmological observables CMB
accélération
acceleration
décélération lente
slow deceleration
décélération rqpide
fast deceleration
accélération
acceleration
?
z1100
inflation
RD (radiation domination)
MD (matter domination)
dark energy domination
Anisotropies of the Cosmic Microwave Background
? photon power spectra
CMB temperature/polarization anisotropies
44
CMB TT DATA
45
CMB TT DATA
46
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 O?
    today implies a change in the spatial curvature
    or other Oi . The background evolution is
    modified
  • Ex in a flat universe,
  • keep O?OcdmObO?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
Write a Comment
User Comments (0)
About PowerShow.com