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MASSIVE NEUTRINOS AND COSMOLOGY. ν. Sergio Pastor (IFIC). CuTAPP 2005, Ringberg Castle. Outline. Neutrinos as DM. Effect of neutrino mass on cosmological observables. Current bounds and future sensitivities. Neutrinos decoupled at T~MeV, keeping a

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Massive neutrinos and cosmology

MASSIVE NEUTRINOS AND COSMOLOGY

ν

Sergio Pastor (IFIC)

CuTAPP 2005,

Ringberg Castle


Outline
Outline

Neutrinos as DM

Effect of neutrino mass

on cosmological observables

Current bounds and

future sensitivities


The cosmic neutrino background

Neutrinos decoupled at T~MeV, keeping a

spectrum as that of a relativistic species

  • Number density

  • Energy density

Massless

Massive mν>>T

The Cosmic Neutrino Background


Primordial

Nucleosynthesis

BBN

Cosmic Microwave Background

CMB

Formation of Large Scale Structures

LSS

T ~ MeV

T < eV

Non-instantaneous ν decoupling

(including oscillations)

νevsνμ,τ Neff

No flavor sensitivityNeff & mν

T.Pinto et al, in preparation

Relic neutrinos influence several cosmological epochs


Neutrinos as dark matter
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


Neutrinos as dark matter1
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


Neutrinos as hot dark matter
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


Cmb data increasing precision

Map of CMBR temperature

Fluctuations

Multipole Expansion

Angular Power Spectrum

CMB DATA: INCREASING PRECISION


Galaxy redshift surveys

2dFGRS

Galaxy Redshift Surveys

SDSS

~ 1300 Mpc


Power spectrum of density fluctuations

Field of density

Fluctuations

CMB experiments

SDSS

Galaxy Surveys

Matter power spectrum is

the Fourier transform of the

two-point correlation function

Power Spectrum of density fluctuations


Power spectrum of density fluctuations1

SDSS

kmax

Power spectrum of density fluctuations

Bias b2(k)=Pg(k)/Pm(k)

Non-linearity

2dFGRS


Neutrinos as hot dark matter1

W. Hu

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


Effect of massive neutrinos on the cmb and matter power spectra
Effect of massive neutrinos on the CMB and Matter Power Spectra

Max Tegmark

www.hep.upenn.edu/~max/


Cosmological bounds on neutrino mass es
Cosmological bounds on neutrino mass(es) Spectra

A unique cosmological bound on mνDOES NOT exist !

  • Different analyses have found upper bounds on neutrino masses, since they depend on

  • The assumed cosmological model: number of parameters (problem of parameter degeneracies)

  • The combination of cosmological data used


Cosmological parameters example
Cosmological Parameters: example Spectra

SDSS Coll, PRD 69 (2004) 103501


Cosmological data
Cosmological Data Spectra

  • 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,σ8)

  • *Lyman-α forest: independent measurement of power on small scales

  • Priors on parameters from other data: SNIa (Ωm), HST (h), …


Neutrino masses in 3 neutrino schemes

eV Spectra

m0

Neutrino masses in 3-neutrino schemes

From present evidences of atmospheric and solar neutrino oscillations

eV

solar

atm

atm

solar

3 degenerate massive neutrinos

Σmν = 3m0




Neutrino masses in 3 neutrino schemes1

+ HST, SNI-a [ Spectraσ8]

+ Ly-α [bias]

Neutrino masses in 3-neutrino schemes

CMB + galaxy clustering

Fig from Strumia & Vissani, hep-ph/0503246


Global analysis oscillations tritium decay 0 2 cosmology
Global analysis: Spectra oscillations + tritium  decay + 02 + Cosmology

CMB + 2dF

Fogli et al., PRD 70 (2004) 113003


The bound depends on the number of neutrinos

WMAP + Other CMB + 2dF + HST + SN-Ia Spectra

3 ν

4 ν

Hannestad JCAP 0305 (2003) 004

(also Elgarøy & Lahav, JCAP 0304 (2003) 004)

95% CL

5 ν

Hannestad

The bound depends on the number of neutrinos

  • Example: in the 3+1 scenario, there are 4 neutrinos (including thermalized sterile)

  • Calculate the bounds with Nν > 3

Abazajian 2002, di Bari 2002


M and n eff degeneracy

(0 eV,3) Spectra

(0 eV,3)

(0 eV,7)

(0 eV,7)

(2.25 eV,7)

(2.25 eV,7)

Σmν and Neff degeneracy


Analysis with m and n eff free
Analysis with SpectraΣmν and Neff free

Previous + priors (HST + SN-Ia)

WMAP + ACBAR + SDSS + 2dF

2σ upper bound on Σmν (eV)

Hannestad & Raffelt, JCAP 0404 (2004) 008

Crotty, Lesgourgues & SP, PRD 69 (2004) 123007


Non thermal relic neutrinos

Thermal SpectraFD spectrum

Distortion from  decay

Cuoco, Lesgourgues, Mangano & SP, astro-ph/0502465

Non-thermal relic neutrinos

 The spectrum could be distorted after neutrino decoupling

Example: decay of a

light scalar after BBN

  • CMB + LSS data still compatible with large deviations from a thermal neutrino spectrum (degeneracy NT distortion – Neff)

  • * Better expectations for future CMB + LSS data, but model degeneracy NT- Neff remains


Future sensitivities to m

Sensitivity to Spectra

With current best-fit values

Future sensitivities to Σmν

  • Next CMB data from WMAP and PLANCK (+ other CMB experiments on large l’s) 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 ΩΛ=0 models

Hu et al, PRL 80 (1998) 5255

Recent update:Lesgourgues, SP & Perotto, PRD 70 (2004) 045016

Fiducial cosmological model:

(Ωbh2 , Ωmh2 , h , ns , τ, Σmν) = (0.0245, 0.148, 0.70 , 0.98, 0.12,Σmν)


Planck sdss

Ideal CMB+40xSDSS Spectra

Σm

Σm

PLANCK+SDSS

2 sensitivity

Fiducial value

  • 0.21 eV (PLANCK+SDSS)

  • 0.13 eV (CMBpol+SDSS)

Σm detectable at 2σ if larger than

Lesgourgues, SP & Perotto, PRD 70 (2004) 045016


Future sensitivities to m new ideas

galaxy weak lensing Spectra and CMB lensing

Future sensitivities to Σmν: new ideas

no bias uncertainty

small scales in linear regime

makes CMB sensitive to

much smaller masses


Future sensitivities to m new ideas1

galaxy weak lensing Spectra and CMB lensing

Future sensitivities to Σmν: new ideas

sensitivity of future weak lensing survey

(4000º)2 to mν

σ(mν) ~ 0.1 eV

Abazajian & Dodelson

PRL 91 (2003) 041301

sensitivity of CMB

(primary + lensing)

to mν

σ(mν) = 0.15 eV (Planck)

σ(mν) = 0.044 eV (CMBpol)

Kaplinghat, Knox & Song

PRL 91 (2003) 241301


Neutrino masses in 3 neutrino schemes2

KATRIN Spectra

PLANCK + SDSS

CMBpol + SDSS

CMBpol (including

CMB lensing)

Neutrino masses in 3-neutrino schemes

CMB + galaxy clustering

+ HST, SNI-a [σ8]

+ Ly-α [bias]

Fig from Strumia & Vissani, hep-ph/0503246


Conclusions
Conclusions Spectra

Cosmological observables efficiently constrain some properties of (relic) neutrinos

ν

Bounds on the sum of neutrino masses from CMB + 2dFGRS or SDSS, and other cosmological data (best Σmν<0.42 eV, conservative Σmν<1 eV)

Sub-eV sensitivity in the next future

(0.1-0.2 eV and better)  Test degenerate

mass region and eventually the IH case


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