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