MASSIVE NEUTRINOS AND COSMOLOGY

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MASSIVE NEUTRINOS AND COSMOLOGY
?
Electroweak Interactions and Unified
Theories, Moriond 2005

• Sergio Pastor (IFIC)

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The Cosmic Neutrino Background
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Relic neutrinos influence several cosmological
epochs
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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
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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

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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

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CMB DATA INCREASING PRECISION
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Galaxy Redshift Surveys
SDSS
1300 Mpc
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Power Spectrum of density fluctuations
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Power spectrum of density fluctuations
Bias b2(k)Pg(k)/Pm(k)
Non-linearity
2dFGRS
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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

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Effect of massive neutrinos on the CMB and Matter
Power Spectra
Max Tegmark www.hep.upenn.edu/max/
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Cosmological bounds on neutrino mass(es)
A unique cosmological bound on m? DOES NOT exist !

• Different analyses have found upper bounds on
  neutrino masses, but they depend on
• The assumed cosmological model number of
  parameters (problem of parameter degeneracies)
• The combination of cosmological data used

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Cosmological Parameters example
SDSS Coll, PRD 69 (2004) 103501
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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,s8)
• Lyman-a forest independent measurement of
  power on small scales
• Priors on parameters from other data SNIa (Om),
  HST (h),

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Neutrino masses in 3-neutrino schemes
From present evidences of atmospheric and solar
neutrino oscillations
eV
solar
atm
atm
solar
3 degenerate massive neutrinos Sm? 3m0
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Neutrino masses in 3-neutrino schemes
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Absolute mass scale searches
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Cosmological bounds on neutrino mass since 2003
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Neutrino masses in 3-neutrino schemes
Currently disfavored
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Global analysis ? oscillations tritium ?
decay 0?2? Cosmology
Fogli et al., PRD 70 (2004) 113003
CMB 2dF
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Future sensitivities to Sm?

• Next CMB data from WMAP and PLANCK ( other CMB
  experiments on large ls) 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 O?0 models

Hu et al, PRL 80 (1998) 5255
Recent update Lesgourgues, SP Perotto, PRD
70 (2004) 045016 Fiducial cosmological
model (Obh2 , Omh2 , h , ns , t, Sm? ) (0.0245
, 0.148 , 0.70 , 0.98 , 0.12, Sm? )
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PLANCKSDSS
2? sensitivity
Fiducial value
0.21 eV (PLANCKSDSS) 0.13 eV (CMBpolSDSS)
Sm detectable at 2s if larger than
Lesgourgues, SP Perotto, PRD 70 (2004) 045016
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Future sensitivities to Sm? new ideas
galaxy weak lensing and CMB lensing
no bias uncertainty small scales in linear regime
makes CMB sensitive to much smaller masses
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Future sensitivities to Sm? new ideas
galaxy weak lensing and CMB lensing
sensitivity of future weak lensing
survey (4000º)2 to m? s(m?) 0.1 eV Abazajian
Dodelson PRL 91 (2003) 041301
sensitivity of CMB (primary lensing) to
m? s(m?) 0.15 eV (Planck) s(m?) 0.04 eV
(CMBpol) Kaplinghat, Knox Song PRL 91 (2003)
241301
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Conclusions
Cosmological observables efficiently constrain
some properties of (relic) neutrinos
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Bounds on the sum of neutrino masses from CMB
2dFGRS or SDSS, and other cosmological data (best
Sm?lt0.42 eV, conservative Sm?lt1 eV)
Sub-eV sensitivity in the next future (0.1-0.2
eV and better) ? Test degenerate mass region and
eventually the IH case