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Cosmological aspects of neutrinos (III)

Cosmological aspects of neutrinos (III). ν. Sergio Pastor (IFIC Valencia) JIGSAW 2007 TIFR Mumbai, February 2007. Cosmological aspects of neutrinos. 3rd lecture. keV sterile neutrinos as Dark Matter. Bounds on m ν from CMB, LSS and other data. Bounds on the radiation content (N eff ).

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Cosmological aspects of neutrinos (III)

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  1. Cosmological aspects of neutrinos (III) ν Sergio Pastor (IFIC Valencia) JIGSAW 2007 TIFR Mumbai, February 2007

  2. Cosmological aspects of neutrinos 3rd lecture keV sterile neutrinos as Dark Matter Bounds on mν from CMB, LSS and other data Bounds on the radiation content (Neff) Future sensitivities on mν from cosmology

  3. Neutrino oscillations in the Early Universe Neutrino oscillations are effective when medium effects get small enough Compare oscillation term with effective potentials Coupled neutrinos Oscillation term prop. to Δm2/2E Second order matter effects prop. to GF(E/MZ2 )[ρ(e-)+ρ(e+)] First order matter effects prop. to GF[n(e-)-n(e+)] Strumia & Vissani, hep-ph/0606054

  4. Mixing angle suppressed by medium effects until T falls below T≈130 MeV(m2/keV2)1/6 keV sterile neutrinos mixed with active species Consider 2ν active-sterile mixing with m2 of order keV2 and very small mixing angle Probability of conversion in the primordial plasma (active neutrinos still interacting) λosc=oscillation length λs=scattering length

  5. The heavy state decays radiatively (with lifetime larger than the age of the Universe): search for X-ray photon line Abazajian et al 2001, Dolgov & Hansen 2002 keV states created in partial equilibrium with the right DM density Would behave as Warm Dark Matter: lower limits from Structure Formation See e.g. Viel et al 2006 Dodelson & Widrow 1994 Shi & Fuller 1999 Abazajian et al 2001 Dolgov & Hansen 2002 Kusenko, Neutrino 2006

  6. Bounds on mν from CMB, LSS and other data

  7. Effect of massive neutrinos on the CMB and Matter Power Spectra Max Tegmark www.hep.upenn.edu/~max/

  8. Neutrinos as Hot Dark Matter Massive Neutrinos can still be subdominant DM: limits on mν from Structure Formation (combined with other cosmological data)

  9. DATA How to get a bound (measurement) of neutrino masses from Cosmology Fiducial cosmological model: (Ωbh2 , Ωmh2 , h , ns , τ, Σmν) PARAMETER ESTIMATES

  10. 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,σ8) • *Lyman-α forest: independent measurement of power on small scales • * Baryon acoustic oscillations (SDSS) • Bounds on parameters from other data: SNIa (Ωm), HST (h), …

  11. Cosmological Parameters: example SDSS Coll, PRD 69 (2004) 103501

  12. ν Cosmological bounds on neutrino mass(es) A unique cosmological bound on mνDOES NOT exist !

  13. Cosmological bounds on neutrino mass(es) A unique cosmological bound on mνDOES NOT exist ! • Different analyses have found upper bounds on neutrino masses, since they depend on • The combination of cosmological data used • The assumed cosmological model: number of parameters (problem of parameter degeneracies) • The properties of relic neutrinos

  14. Cosmological bounds on neutrino masses using WMAP3 Dependence on the data set used. An example: Fogli et al., hep-ph/0608060

  15. + HST, SNI-a… + BAO and/or bias + including Ly-α Neutrino masses in 3-neutrino schemes CMB + galaxy clustering Lesgourgues & SP, Phys. Rep. 429 (2006) 307

  16. Tritium  decay, 02 and Cosmology Fogli et al., hep-ph/0608060

  17. 02 and Cosmology Fogli et al., hep-ph/0608060

  18. Relativistic particles in the Universe At T<me, the radiation content of the Universe is Effective number of relativistic neutrino species Traditional parametrization of the energy density stored in relativistic particles

  19. Extra relativistic particles • 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 on Neff from BBN and from CMB+LSS

  20. Effect of Neff at later epochs • Neff modifies the radiation content: • Changes the epoch of matter-radiation equivalence

  21. 95% CL Crotty, Lesgourgues & SP, PRD 67 (2003) Hannestad, JCAP 0305 (2003) Pierpaoli, MNRAS 342 (2003) 95% CL CMB+LSS: allowed ranges for Neff • Set of parameters: ( Ωbh2 , Ωcdmh2 , h , ns , A , b , Neff ) • DATA: WMAP + other CMB + LSS + HST (+ SN-Ia) • Flat Models • Non-flat Models • Recent result Hannestad & Raffelt, astro-ph/0607101 95% CL

  22. Allowed ranges for Neff Using cosmological data (95% CL) Mangano et al, astro-ph/0612150

  23. Future bounds on Neff • Next CMB data from WMAP and PLANCK (other CMB experiments on large l’s) temperature and polarization spectra • Forecast analysis in ΩΛ=0 models Lopez et al, PRL 82 (1999) 3952 PLANCK WMAP

  24. Future bounds on Neff Updated analysis: Larger errors ΔNeff ~ 3 (WMAP) ΔNeff ~ 0.2 (Planck) Bowen et al 2002 Bashinsky & Seljak 2003

  25. WMAP + Other CMB + 2dF + HST + SN-Ia 3 ν 4 ν Hannestad JCAP 0305 (2003) 004 (also Elgarøy & Lahav, JCAP 0304 (2003) 004) 95% CL 5 ν Hannestad The bound on Σmν 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

  26. (0 eV,3) (0 eV,3) (0 eV,7) (0 eV,7) (2.25 eV,7) (2.25 eV,7) Σmν and Neff degeneracy

  27. BBN allowed region Analysis with Σmν 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

  28. BBN allowed region BBN allowed region Analysis with Σmν and Neff free WMAP + ACBAR + SDSS + 2dF Hannestad & Raffelt, JCAP 0611 (2006) 016 Crotty, Lesgourgues & SP, PRD 69 (2004) 123007

  29. Λ WMAP Coll, astro-ph/0603449 Parameter degeneracy: Neutrino mass and w In cosmological models with more parameters the neutrino mass bounds can be relaxed. Ex: quintessence-like dark energy with ρDE=w pDE

  30. Non-standard relic neutrinos The cosmological bounds on neutrino masses are modified if relic neutrinos have non-standard properties (or for non-standard models) Two examples where the cosmological bounds do not apply • Massive neutrinos strongly coupled to a light scalar field: they could annihilate when becoming NR • Neutrinos coupled to the dark energy: the DE density is a function of the neutrino mass (mass-varying neutrinos)

  31. ThermalFD spectrum Distortion from Φdecay Cuoco, Lesgourgues, Mangano & SP, PRD 71 (2005) 123501 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

  32. Future sensitivities to Σmν Future cosmological data will be available from CMB (Temperature & Polarization anis.) Galaxy redshift surveys Galaxy cluster surveys Weak lensing surveys CMB lensing WMAP, SPT, ACT, BICEP, QUaD, BRAIN, ClOVER, PLANCK, SAMPAN, Inflation Probe, SDSS, SDSS-II, ALHAMBRA, KAOS, DES, CFHTLS, SNAP, LSST, Pan-STARRS, DUO…

  33. Σm detectable at 2σ if larger than • 0.21 eV (PLANCK+SDSS) • 0.13 eV (CMBpol+SDSS) Lesgourgues, SP & Perotto, PRD 70 (2004) 045016 PLANCK+SDSS • Fisher matrix analysis: expected sensitivities assuming a fiducial cosmological model, for future experiments with known specifications Fiducial cosmological model: (Ωbh2 , Ωmh2 , h , ns , τ, Σmν) = (0.0245, 0.148, 0.70 , 0.98, 0.12,Σmν)

  34. weak gravitational and CMB lensing lensing Future sensitivities to Σmν: new ideas No bias uncertainty Small scales much closer to linear regime Tomography: 3D reconstruction Makes CMB sensitive to smaller neutrino masses

  35. weak gravitational and CMB lensing 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

  36. CMB lensing: recent analysis σ(Mν) in eV for future CMB experiments alone : Lesgourgues et al, PRD 73 (2006) 045021

  37. Summary of future sensitivities Lesgourgues & SP, Phys. Rep. 429 (2006) 307 Future cosmic shear surveys

  38. End of 3rd lecture

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