NEUTRINO COSMOLOGY
STEEN HANNESTAD UNIVERSITY OF AARHUSPLANCK ’06, 31 MAY 2006
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LIMITS ON THE PROPERTIES OF LIGHT NEUTRINOS FROM COSMOLOGICAL DATA
THE MASS OF THE ACTIVE SPECIESBOUNDS ON OTHER LIGHT SPECIES
BOUNDS ON NEW NEUTRINO INTERACTIONSTHE NEUTRINOLESS UNIVERSE?BOUNDS ON THE DECAY OF LIGHT NEUTRINOS
NEUTRINOS, THE MICROWAVE BACKGROUND,AND LARGE SCALE STRUCTURE
WMAP PROJECT, PUBLISHED CMB DATA MARCH 2006
THE TEMPERATURE MAP IN THE 94 GHZ CHANNEL
THE AVAILABLECMB DATAAS OF 5/2006
LARGE SCALE STRUCTURE DATA FROM SDSS AND 2dFGRS
SDSS
OTHER AVAILABLE STRUCTURE FORMATION DATA:
THE LYMAN ALPHA FOREST (THE FLUX POWER SPECTRUMON SMALL SCALES AT HIGH REDSHIFT)
McDonald et al. astro-ph/0407377 (SDSS)Viel et al.
THE BARYON ACOUSTIC PEAK (SDSS) – THE CMB OSCILLATIONPATTERN, SEEN IN BARYONS
WEAK GRAVITATIONAL LENSINGCFHTLS
Power Spectrum of CosmicDensity Fluctuations
FROM MAX TEGMARK
EISENSTEIN ET AL. 2005 (SDSS)
THE SDSS MEASUREMENT OF BARYON OSCILLATIONS IN THEPOWER SPECTRUM PROVIDE A FANTASTICALLY PRECISEMEASURE OF THE ANGULAR DISTANCE SCALE AND TURNS OUT TO BE EXTREMELY USEFUL FOR PROBING NEUTRINO PHYSICS
WHAT ABOUT NEUTRINO PHYSICS?
NEUTRINO MASS HIERARCHY AND MIXING MATRIX
ABSOLUTE NEUTRINO MASSES
NUMBER OF RELIC NEUTRINOS / RELATIVISTIC ENERGY
EXOTIC NEUTRINO PROPERTIESNEW INTERACTIONSSTERILE STATES…….
Normal hierarchy Inverted hierarchy
If neutrino masses are hierarchical then oscillation experimentsdo not give information on the absolute value of neutrino masses
However, if neutrino masses are degenerate
no information can be gained from such experiments.Experiments which rely on the kinematics of neutrino massare the most efficient for measuring m0 (or 0n2b decays)
SOLAR nKAMLAND
ATMO. nK2K
Tritium decay endpoint measurements have reached limitson the electron neutrino mass
This translates into a limit on the sum of the three mass eigenstates
! " eV 7im
Mainz experiment, final analysis (Kraus et al.)
THE ABSOLUTE VALUES OF NEUTRINO MASSESFROM COSMOLOGY
NEUTRINOS AFFECT STRUCTURE FORMATIONBECAUSE THEY ARE A SOURCE OF DARK MATTER
HOWEVER, eV NEUTRINOS ARE DIFFERENT FROM CDM BECAUSE THEY FREE STREAM
SCALES SMALLER THAN dFS DAMPED AWAY, LEADS TOSUPPRESSION OF POWER ON SMALL SCALES
Sm = 0 .3 eV
FINITE NEUTRINO MASSES SUPPRESS THE MATTER POWERSPECTRUM ON SCALES SMALLER THAN THE FREE-STREAMINGLENGTH
Sm = 1 eV
Sm = 0 eV
COMBINED ANALYSIS OF WMAP AND LSSDATA (Spergel et al. 2006)
WMAP-3 ONLY ~ 2.0 eVWMAP + LSS 0.68 eV
COMPARE WITH WMAP-I:
WMAP-1 ONLY ~ 2.1 eVWMAP + LSS ~ 0.7 eV(without information on bias)
WHAT IS THE PRESENT BOUND ON THE NEUTRINO MASS?
HOW CAN THE BOUND BE AVOIDED?
CHANGE THE PRIMORDIAL SPECTRUMYES, BUT LEADS TO OTHER PROBLEMS
TOPOLOGICAL DEFECTS?NO
MAKE THE NEUTRINOS STRONGLY INTERACTINGNO (TO COME)
CHANGE THE DARK ENERGY EQUATION OF STATEYES (BUT NO)
……
STH, ASTRO-PH/0505551 (PRL)
EXAMPLE:
THERE IS A VERY STRONG DEGENERACY BETWEEN NEUTRINOMASS AND THE DARK ENERGY EQUATION OF STATETHIS SIGNIFICANTLY RELAXES THE COSMOLOGICAL BOUND ONNEUTRINO MASS
MAKING THE BOUND SIGNIFICANTLY STRONGER REQUIRES THE USE OF OTHER DATA:
EITHER ADDITIONAL DATA TO FIX THE Wm – w DEGENERACYTHE BARYON ACOUSTIC PEAK
OR
FIXING THE SMALL SCALE AMPLITUDELYMAN – ALPHA DATA
GOOBAR, HANNESTAD, MÖRTSELL, TU (astro-ph/0602155, JCAP)
10 FREE PARAMETERS
WMAP, BOOMERANG, CBISDSS, 2dFSNLS SNI-A
10 FREE PARAMETERS
WMAP, BOOMERANG, CBISDSS, 2dFSNLS SNI-A, SDSS BARYONS
11 FREE PARAMETERS
WMAP, BOOMERANG, CBISDSS, 2dFSNLS SNI-A, SDSS BARYONS
WITH THE INCLUSION OF LYMAN-ALPHA DATA THE BOUND STRENGTHENSTO
No BAO
BAO
LY-aBAO+LY-a
USING THE BAO DATA THE BOUNDIS STRENGTHENED, EVEN FORVERY GENERAL MODELS
SELJAK, SLOSAR & MCDONALD (ASTRO-PH/0604335) FIND
IN THE SIMPLEST 8-PARAMETER MODEL FRAMEWORK WITH NEW SDSSLYMAN-ALPHA ANALYSIS.NOTE, HOWEVER, THAT THIS DATA IS (EVEN MORE) INCOMPATIBLE WITHTHE WMAP NORMALIZATION.VIEL ET AL. FIND DIFFERENT NORMALIZATION BASED ON DIFFERENT ANALYSIS OF THE SAME DATA.
SELJAK, SLOSAR & MCDONALD
SDSS LYMAN-ALPHA
WMAP-3 NORMALIZATION
SELJAK, SLOSAR & MCDONALD (ASTRO-PH/0604335) FIND
IN THE SIMPLEST 8-PARAMETER MODEL FRAMEWORK WITH NEW SDSSLYMAN-ALPHA ANALYSIS.NOTE, HOWEVER, THAT THIS DATA IS (EVEN MORE) INCOMPATIBLE WITHTHE WMAP NORMALIZATION.VIEL ET AL. FIND DIFFERENT NORMALIZATION BASED ON DIFFERENT ANALYSIS OF THE SAME DATA.
SELJAK, SLOSAR & MCDONALD
SDSS LYMAN-ALPHA
WMAP-3 NORMALIZATION
GOOBAR, HANNESTAD, MORTSELL, TU (ASTRO-PH/0602155)
OLD SDSS LYMAN-ALPHA
NEW SDSS LYMAN-ALPHA
VIEL ET AL. LYMAN-ALPHA
SELJAK, SLOSAR & MCDONALD (ASTRO-PH/0604335) FIND
IN THE SIMPLEST 8-PARAMETER MODEL FRAMEWORK WITH NEW SDSSLYMAN-ALPHA ANALYSIS.NOTE, HOWEVER, THAT THIS DATA IS (EVEN MORE) INCOMPATIBLE WITHTHE WMAP NORMALIZATION.VIEL ET AL. FIND DIFFERENT NORMALIZATION BASED ON DIFFERENT ANALYSIS OF THE SAME DATA.
SELJAK, SLOSAR & MCDONALD
SDSS LYMAN-ALPHA
WMAP-3 NORMALIZATION
GOOBER, HANNESTAD, MORTSELL, TU (ASTRO-PH/0602155)
OLD SDSS LYMAN-ALPHA
NEW SDSS LYMAN-ALPHA
VIEL ET AL. LYMAN-ALPHA
BOTTOM LINE: SYSTEMATICS IN LYMAN-ALPHA ARE STILL NOTPROPERLY UNDERSTOOD!IT INVOLVES COMPLICATED GAS DYNAMICS AT HIGH REDSHIFTTHE DATA SHOULD BE USED WITH EXTREME CAUTION.
HANNESTAD, TU, WONG (2006)
WHAT IS TO COME IN THE FUTURE?
WITHIN THE NEXT 5-10YEARS NEW OBSERVA-TIONS WILL PUSH THEBOUND ON NEUTRINOMASS BELOW 0.05 Ev
WE WILL KNOW IF NEUTRINO MASSES AREHIERARCHICAL!
WEAK GRAVITATIONALLENSING IS THE BESTPROBE (COMBINED WITHCMB)
NEW PROJECTS ARE UNDERWAYPanSTARRS, LSST, ETC
FOR ANY THERMALLY PRODUCED PARTICLE IT ISSTRAIGHTFORWARD TO CALCULATE THE DECOUPLINGEPOCH ETC.THE ONLY IMPORTANT PARAMETERS ARE
WHERE g* IS THE EFECTIVE NUMBER OF DEGREES OFFREEDOM WHEN X DECOUPLES.
AND
CONTRIBUTION TO DENSITY
FREE-STREAMING LENGTH
WHAT ABOUT OTHER LIGHT, THERMALLYPRODUCED PARTICLES?
EW transition (~ 100 GeV)g* = 106.75
Density bound for a Majorana fermion
STH, hep-ph/0409108 (See also STH & G Raffelt, JCAP 0404, 008)
Based on WMAP-1, SDSS, SNI-a and Lyman-a data
MASS BOUND FOR SPECIES DECOUPLINGAROUND EW TRANSITION
DECOUPLING AFTERQCD PHASE TRANSITIONLEADS TO
Below QCD transition(~ 100 MeV) g* < 20
COULD NEUTRINOS BE STRONGLY INTERACTING?
BEACOM, BELL & DODELSON (2004) SUGGESTED A WAY TO EVADETHE COSMOLOGICAL NEUTRINO MASS BOUND:
IF NEUTRINOS COUPLE STRONGLY ENOUGH WITH A MASSLESSSCALAR OR PSEUDO-SCALAR THEY CAN BE VERY MASSIVE, BUTHAVE NO EFFECT ON THE MATTER POWER SPECTRUM,EXCEPT FOR A SLIGHT SUPPRESSION DUE TO MORE RELATIVISTICENERGY DENSITY
WHY? BECAUSE NEUTRINOS WOULD ANNIHILATE AND DISAPPEARAS SOON AS THEY BECOME NON-RELATIVISTIC
BEACOM, BELL & DODELSON 2004
HOWEVER, NEUTRINOS WHICH ARE STRONGLY INTERACTING DURINGRECOMBINATION ARE NOT AFFECTED BY SHEAR (EFFECTIVELY THEYBEHAVE LIKE A FLUID).THIS HAS IMPLICATIONS FOR CMB BECAUSE THE NEUTRINO POTENTIAL FLUCTUATIONS SOURCING THE CMB FLUCTUATIONS DO NOT DECAY
THIS INCREASES THE CMB AMPLITUDE ON ALL SCALES SMALLER THANTHE HORIZON AT RECOMBINATION
Sth, astro-ph/0411475
Strongly interacting neutrinos
Standard model neutrinos
SUCH STRONGLY INTERACTING NEUTRINOS ARE HIGHLYDISFAVOURED BY DATA
(STH 04, BELL, PIERPAOLI & SIGURDSON 05)ALTHOUGH THE EXACT VALUE OF THE DISCREPANCYIS NOT FULLY SETTLED (but at least by Dc2 > 20 even with more d.o.f.)
THIS CAN BE USED TO PUT THE STRONGEST KNOWN CONSTRAINTSON NEUTRINO COUPLINGS TO MASSLESS SCALARS OR PSEUDOSCALARS (STH & RAFFELT HEP-PH/0509278 (PRD))
WE FIND
Diagonal elements
Off-diagonal elements
FOR DERIVATIVE COUPLINGS THE BOUND WOULD BECOME EVENSTRONGER
THE BOUND ON g CAN BE TRANSLATED INTO A BOUND ONTHE NEUTRINO LIFETIME
THIS BOUND FOR INSTANCE EXCLUDES THAT THERE SHOULD BE SIGNIFICANT NEUTRINO DECAY IN BEAMS FROM HIGH-ENERGYASTROPHYSICAL SOURCES (STH & RAFFELT 2005)
CONCLUSIONS
NEUTRINO PHYSICS IS PERHAPS PRIME EXAMPLE OF HOW TO USE COSMOLOGY TO DO PARTICLE PHYSICS
THE BOUND ON NEUTRINO MASSES IS ALREADY AN ORDER OF MAGNITUDE STRONGER THAN THAT FROM DIRECT EXPERIMENTS, ALBEIT MORE MODEL DEPENDENT
WITHIN THE NEXT 5-10 YEARS THE MASS BOUND WILLREACH THE LEVEL NEEDED TO DETECT HIERARCHICALNEUTRINO MASSES
THE FACT THAT CMB DOES NOT ALLOW STRONGLY INTERACTING NEUTRINOS SETS VERY INTERESTING CONSTRAINTS ON NEUTRINO PROPERTIES