RELIC NEUTRINOS: NEUTRINO PROPERTIES FROM COSMOLOGY Sergio Pastor (IFIC) ν

Massive neutrinos Standard neutrinos Extra radiation and Neutrino asymmetries RELIC NEUTRINOS: OUTLINE

RELIC NEUTRINOS Massive neutrinos Standard neutrinos Extra radiation and Neutrino asymmetries

Neutrinos in equilibrium f ν (p,T)=f FD (p,T) Standard Relic Neutrinos

T ν = T e = T γ 1 MeV  T  m μ Neutrinos in Equilibrium

Neutrinos in equilibrium f ν (p,T)=f FD (p,T) Standard Relic Neutrinos

Neutrino decoupling

Decoupled Neutrinos f ν (p)=f FD (p,T ν ) T dec ( ν e ) ~ 2.3 MeV T dec ( ν μ,τ ) ~ 3.5 MeV Neutrino decoupling

At T~m e, electron-positron pairs annihilate heating photons but not the decoupled neutrinos Decoupled neutrinos stream freely until non-relativistic Neutrino and Photon temperatures

Number density Energy density Neutrinos after decoupling Massless Massive m ν >>T

Neutrinos and Cosmology Neutrinos influence several cosmological scenarios Primordial Nucleosynthesis BBN Cosmic Microwave Background CMB Formation of Large Scale Structures LSS z~10 10 z~1000

RELIC NEUTRINOS Massive neutrinos Standard neutrinos Extra radiation and Neutrino asymmetries

At T<<m e, the radiation content of the Universe is Effective number of relativistic neutrino species Traditional parametrization of the energy density stored in relativistic particles Neff is not exactly 3 for standard neutrinos (if m ν <<T) Relativistic particles in the Universe

But, since T dec ( ν e ) ~ m e, neutrinos slightly share a small part of the entropy release At T~m e, e + e - pairs annihilate heating photons Non-instantaneous neutrino decoupling

But, since T dec ( ν e ) ~ m e, neutrinos slightly share a small part of the entropy release T ν 0.15% larger ρ(ν e ) 1% larger ρ(ν μ,τ ) 0.5% larger f ν =f FD (p,T ν )[1+δf(p)] Non-instantaneous decoupling + QED corrections to e.m. plasma Neff= Mangano et al 2002 Non-instantaneous neutrino decoupling

Extra radiation can be: scalars, pseudoscalars, sterile neutrinos (totally or partially thermalized, bulk), neutrinos in very low-energy reheating scenarios, relativistic decay products of heavy particles… Particular case: relic neutrino asymmetries Constraints from BBN and from CMB+LSS Extra relativistic particles

Produced elements: D, 3 He, 4 He, 7 Li and small abundances of others BBN: Creation of light elements Standard BBN: the baryon density is the sole parameter

Fields & Sarkar PDG 2002 BBN: Predictions vs Observations After WMAP Ω B h 2 =0.023±0.001

Effect of N eff on BBN N eff fixes the expansion rate during BBN  (N eff )>  0   4 He Burles, Nollett & Turner

Cyburt et al, astro-ph/ BBN: allowed ranges for N eff Hannestad astro-ph/ Not significantly different from previous analyses Lisi et al 1999, Esposito et al 2000, Burles et al 2001, Cyburt et al 2002… Hannestad astro-ph/

CMB DATA: FIRST YEAR WMAP vs COBE

Map of CMBR temperature Fluctuations Multipole Expansion CMB DATA: INCREASING PRECISION Angular Power Spectrum

CMB DATA: INCREASING PRECISION Degrees (θ)

CMB DATA: FIRST YEAR OF WMAP

Effect of N eff on CMB N eff modifies the radiation content: Changes the epoch of matter-radiation equivalence

Pierpaoli astro-ph/ CMB+LSS: allowed ranges for N eff Crotty, Lesgourgues & SP, astro-ph/ Problem: parameter degeneracies Set of parameters: ( Ω b h 2, Ω cdm h 2, h, n s, A, b, N eff ) DATA: WMAP + other CMB + 2dF + HST (+ SN-Ia) Upper bound on h important to fix upper limit on N eff Flat Models Non-flat Models 95% CL

Future bounds on N eff Next CMB data from WMAP and PLANCK (other CMB experiments on large l’s) temperature and polarization spectra Forecast analysis in Ω Λ =0 models Lopez et al, PRL 82 (1999) 3952 WMAP PLANCK Recent analysis: Larger errors Bowen et al 2002 ΔN eff ~ 3 (WMAP) ΔN eff ~ 0.2 (Planck)

Neutrinos in equilibrium f ν (p,T)=f FD (p,T) Degenerate Relic Neutrinos    /T

Relic neutrino asymmetries Raffelt Fermi-Dirac spectrum with temperature T and chemical potential  More radiation

Degenerate Nucleosynthesis If   0, for any flavor  (  )>  (0)   4 He Plus the direct effect on n  p if  ( e )  0  e >0   4 He Pairs  (  e,  N ) that produce the same observed abundances for larger  B Kang & Steigman 1992

Hansen et al 2001Hannestad 2003 Combined bounds BBN & CMB-LSS In the presence of flavor oscillations ? Degeneracy direction (arbitrary ξ e )

Flavor neutrino oscillations in the Early Universe Density matrix Mixing matrix Expansion of the Universe Charged lepton background (finite T contribution) Collisions (damping) Neutrino background: diagonal and off-diagonal potentials Dominant term: Synchronized Neutrino Oscillations

Effective flavor equilibrium (almost) established  BBN Evolution in ATM + solar LMA (  13 =0) Dolgov et al 2002

Synchronized neutrino oscillations Small conversion before the onset of BBN BBN Evolution in ATM + solar LOW (  13 =0)

RELIC NEUTRINOS Extra radiation and Neutrino asymmetries Standard neutrinos Massive neutrinos

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

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

Power Spectrum of density fluctuations Massive Neutrinos can still be subdominant DM: limits on m ν from Structure Formation Galaxy Surveys CMB experiments

Neutrinos as Hot Dark Matter W. Hu Effect of Massive Neutrinos: suppression of Power at small scales

Max Tegmark’s homepage Effect of massive neutrinos on the CMB and Matter Power Spectra

2dFGRS Galaxy Survey

~ 1300 Mpc

Power spectrum of density fluctuations from 2dF 2dFGRS [Elgarøy et al] 2002 Bias b 2 (k)=P g (k)/P m (k) Non-linearity

3 degenerate massive neutrinos Σm ν = 3m 0` Neutrino mass in 3-neutrino schemes eV From present evidences of atmospheric and solar neutrino oscillations atm solar m0m0

Direct laboratory bounds on m ν Searching for non-zero neutrino mass in laboratory experiments Tritium beta decay: measurements of endpoint energy m(ν e ) < 2.2 eV (95% CL) Mainz-Troitsk Future experiments (KATRIN) m(ν e ) ~ 0.3 eV Neutrinoless double beta decay: if Majorana neutrinos 76 Ge experiments: Im ee I < 0.35 eV

WMAP+CBI+ACBAR+2dFGRS+Lyman α Spergel et al astro-ph/ Σm ν < 0.71 eV Ω ν h 2 < m 0 < 0.23 eV 95% CL 3 degenerate massive neutrinos Bound on m ν after first year WMAP data

Pierce & Murayama hep-ph/ Strumia hep-ph/ (v4) Giunti hep-ph/ Σm ν < 0.71 eV Ω ν h 2 < Small marginally allowed region 3+1 solution strongly disfavored Is the 3+1 LSND scenario ruled out ? More conservative Σm ν < 1.01 eV Hannestad astro-ph/ Elgarøy & Lahav astro-ph/

Real bound on the 3+1 LSND scenario Take into account the number of neutrino species 3+1 scenario: 4 neutrinos (including thermalized sterile) Calculate the bounds with N ν > 3 Abazajian 2002, di Bari 2002 Hannestad astro-ph/ (also Elgarøy & Lahav, astro-ph/ ) 3 ν 4 ν 5 ν Hannestad 95% CL WMAP + Other CMB + 2dF + HST + SN-Ia 1 massive + 3 massless case not yet considered Crotty, Lesgourgues & SP, in preparation

Future bounds on Σm ν Next CMB data from WMAP and PLANCK (other CMB experiments on large l’s) temperature and polarization spectra SDSS galaxy survey: 10 6 galaxies (250,000 for 2dF) Forecast analysis in WMAP and Ω Λ =0 models Hu et al, PRL 80 (1998) 5255 With current best-fit values

Future bounds on Σm ν Updated analysis: Hannestad astro-ph/ Σm detectable at 2σ if larger than With a galaxy survey ~10 times SDSS eV From weak gravitational lensing: sensitive to both dark energy and neutrino mass. Future ~ 0.1 eV 0.45 eV (WMAP+SDSS) 0.12 eV (PLANCK+SDSS) Abazajian and Dodelson astro-ph/

Stringent limits on potential relic neutrino asymmetries from flavor equilibrium before BBN (lξ ν l<0.07), fixing the cosmic neutrino density to 1% Cosmological observables efficiently constrain some properties of (relic) neutrinos Bounds on the radiation content of the Universe (N eff ) from BBN (with η B input from CMB) and CMB+LSS (N eff <7 at 95%CL) Conclusions Bounds on the sum of neutrino masses from CMB + 2dFGRS (conservative Σm ν <1 eV), with sub-eV sensitivity in the next future