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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 ). - PowerPoint PPT Presentation
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04/21/23
Cosmological aspects of neutrinos (III)
Sergio Pastor (IFIC Valencia)JIGSAW 2007
TIFR Mumbai, February 2007
ν
Cosmological aspects of neutrinos
3rd lecture
Bounds on mν from CMB, LSS and other data
Bounds on the radiation content (Neff)
Future sensitivities on mν from cosmology
keV sterile neutrinos as Dark Matter
Neutrino oscillations in the Early Universe
Neutrino oscillations are effective when medium effects get small enough
Compare oscillation term with effective potentials
Strumia & Vissani, hep-ph/0606054
Oscillation term prop. to Δm2/2E
First order matter effects prop. toGF[n(e-)-n(e+)]
Second order matter effects prop. toGF(E/MZ
2 )[ρ(e-)
+ρ(e+)]
Coupled neutrinos
keV sterile neutrinos mixed with active species
Consider 2ν active-sterile mixing with m2
of order keV2 and very small mixing angleProbability of
conversion in the primordial plasma (active neutrinos still interacting)
λosc=oscillation length λs=scattering length
Mixing angle suppressedby medium effectsuntil T falls belowT≈130 MeV(m2/keV2)1/6
The heavy state decaysradiatively (with lifetimelarger than the age of theUniverse): search for X-rayphoton line
Abazajian et al 2001, Dolgov & Hansen 2002
Kusenko, Neutrino 2006
keV states created in partial equilibrium with the right DM density
Would behave as WarmDark Matter: lower limits from Structure Formation
See e.g. Viel et al 2006
Dodelson & Widrow 1994 Shi & Fuller 1999
Abazajian et al 2001Dolgov & Hansen 2002
Bounds on mν from CMB, LSS and other data
Effect of massive neutrinos on the CMB and Matter Power
Spectra
Max Tegmark
www.hep.upenn.edu/~max/
Neutrinos as Hot Dark Matter
Massive Neutrinos can still be subdominant DM: limits on mν from Structure Formation (combined with other cosmological data)
How to get a bound (measurement) of neutrino masses from Cosmology
DATA
Fiducial cosmological model:(Ωbh2 , Ωmh2 , h , ns , τ, Σmν )
PARAMETERESTIMATES
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), …
Cosmological Parameters: example
SDSS Coll, PRD 69 (2004) 103501
Cosmological bounds on neutrino mass(es)
A unique cosmological bound on mν DOES NOT exist !
ν
Cosmological bounds on neutrino mass(es)
A unique cosmological bound on mν DOES 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
Cosmological bounds on neutrino masses using WMAP3
Fogli et al., hep-ph/0608060
Dependence on the data set used. An example:
Neutrino masses in 3-neutrino schemes
CMB + galaxy clustering
+ HST, SNI-a…
+ BAO and/or bias
+ including Ly-α
Lesgourgues & SP, Phys. Rep. 429 (2006) 307
Tritium decay, 02 and Cosmology
Fogli et al.,
hep-ph/0608060
02 and Cosmology
Fogli et al., hep-ph/0608060
At T<me, the radiation content of the Universe is
Effective number of relativistic neutrino speciesTraditional parametrization of the energy densitystored in relativistic particles
Relativistic particles in the Universe
• 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
Extra relativistic particles
Effect of Neff at later epochs
• Neff modifies the radiation content:
• Changes the epoch of matter-radiation equivalence
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
Pierpaoli, MNRAS 342 (2003)
2.01.9eff 4.1N
95% CL
Crotty, Lesgourgues & SP, PRD 67 (2003)
3.32.1eff 3.5N
95% CL
Hannestad, JCAP 0305 (2003)
3.02.1eff 4.0N
Hannestad & Raffelt, astro-ph/06071014.6N2.7 eff
95% CL
Allowed ranges for Neff
Mangano et al, astro-ph/0612150
Using cosmological data (95% CL)
)-Ly and BAO( 6.2N 3.1
data) LSS(CMB 7.9N 3.0
eff
eff
2B10
B10 h274Ω
10
/nnη
γ
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 modelsLopez et al, PRL 82 (1999) 3952
WMAP
PLANCK
Future bounds on Neff
Updated analysis:Larger errors
Bowen et al 2002
ΔNeff ~ 3 (WMAP)
ΔNeff ~ 0.2 (Planck)
Bashinsky & Seljak 2003
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
Hannestad JCAP 0305 (2003) 004
(also Elgarøy & Lahav, JCAP 0304 (2003) 004)
3 ν4 ν
5 ν
Hannestad
95% CL
WMAP + Other CMB + 2dF + HST + SN-Ia
Σmν and Neff degeneracy
(0 eV,3)
(0 eV,7)
(2.25 eV,7)
(0 eV,3)
(0 eV,7)
(2.25 eV,7)
Analysis with Σmν and Neff free
Hannestad & Raffelt, JCAP 0404 (2004) 008
Crotty, Lesgourgues & SP, PRD 69 (2004) 123007
2σ upper bound on Σmν (eV)
WMAP + ACBAR + SDSS + 2dF Previous + priors (HST + SN-Ia)
BBN allowed region
Analysis with Σmν and Neff free
Crotty, Lesgourgues & SP, PRD 69 (2004) 123007
WMAP + ACBAR + SDSS + 2dF
Hannestad & Raffelt, JCAP 0611 (2006) 016
BBN allowed region
BBN allowed region
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
WMAP Coll, astro-ph/0603449
Λ
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)
Non-thermal relic neutrinos
The spectrum could be distorted after neutrino decoupling
Example: decay of a light scalar after BBN
Cuoco, Lesgourgues, Mangano & SP, PRD 71 (2005) 123501
Thermal FD spectrum
Distortion from Φ decay
* 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
/T p
Future sensitivities to Σmν
CMB (Temperature & Polarization anis.)
Galaxy redshift surveys
Galaxy cluster surveys
Weak lensing surveys
CMB lensing
Future cosmological data will be available from
WMAP, SPT, ACT, BICEP, QUaD, BRAIN, ClOVER, PLANCK, SAMPAN, Inflation Probe, SDSS, SDSS-II, ALHAMBRA, KAOS, DES, CFHTLS, SNAP, LSST, Pan-STARRS, DUO…
PLANCK+SDSS
Lesgourgues, SP & Perotto, PRD 70 (2004) 045016
Σm detectable at 2σ if larger than
0.21 eV (PLANCK+SDSS)
0.13 eV (CMBpol+SDSS)
Fiducial cosmological model:(Ωbh2 , Ωmh2 , h , ns , τ, Σmν ) =
(0.0245 , 0.148 , 0.70 , 0.98 , 0.12, Σmν )
• Fisher matrix analysis: expected sensitivities assuming a fiducial cosmological model, for future experiments with known specifications
Future sensitivities to Σmν: new ideas
weak gravitational and CMB lensing
lensing
No bias uncertaintySmall scales much closer
to linear regimeTomography:
3D reconstruction
Makes CMB sensitive to smaller neutrino masses
Future sensitivities to Σmν: new ideas
sensitivity of future weak lensing survey(4000º)2 to mν
σ(mν) ~ 0.1 eV
Abazajian & DodelsonPRL 91 (2003) 041301
sensitivity of CMB(primary + lensing) to mν
σ(mν) = 0.15 eV (Planck)
σ(mν) = 0.044 eV (CMBpol)
Kaplinghat, Knox & SongPRL 91 (2003) 241301
weak gravitational and CMB lensing
lensing
CMB lensing: recent analysis
σ(Mν) in eV for future CMB experiments alone : Lesgourgues et al, PRD 73 (2006) 045021
Summary of future sensitivities
Lesgourgues & SP, Phys. Rep. 429 (2006) 307
Future cosmic shear surveys
End of 3rd lecture