NEUTRINO MASS FROM LARGE SCALE STRUCTURE

STEEN HANNESTAD CERN, 8 December 2008

e

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 either the kinematics of neutrino massor the spin-flip in neutrinoless double beta decay are the most efficient for measuring m0

catmospherimm 0

SOLAR KAMLAND

ATMO. K2KMINOS

LIGHTEST

INVERTED

NORMAL

HIERARCHICAL DEGENERATE

Lesgourgues and Pastor 2006

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

1eVFS Gpc 1~ md

SCALES SMALLER THAN dFS DAMPED AWAY, LEADS TOSUPPRESSION OF POWER ON SMALL SCALES

eV 932

mh FROM K2

11

43/1

TT

AVAILABLE COSMOLOGICAL DATA

WMAP-5 TEMPERATURE POWER SPECTRUM

M NOLTA ET AL., arXiv:0803.0593

LARGE SCALE STRUCTURE SURVEYS - 2dF AND SDSS

SDSS SPECTRUMTEGMARK ET AL. 2006

astro-ph/0608632

m = 0.3 eV

FINITE NEUTRINO MASSES SUPPRESS THE MATTER POWERSPECTRUM ON SCALES SMALLER THAN THE FREE-STREAMINGLENGTH

m = 1 eV

m = 0 eV

P(k

)/P

(k,m

EISENSTEIN ET AL. 2005 (SDSS)

THE SDSS MEASUREMENT OF BARYON OSCILLATIONS IN THEPOWER SPECTRUM PROVIDES PRECISE MEASURE OF THE ANGULAR DISTANCE SCALE AND TURNS OUT TO BE EXTREMELY USEFUL FOR PROBING NEUTRINO PHYSICS

NEUTRINO MASSES ISA POTENTIALLY IMPOR-TANT SYSTEMATIC ERROR NOT ACCOUNTEDFOR IN THE ANALYSIS

GOOBAR, HANNESTAD, MÖRTSELL, TU 2006

Astro-ph/0807.3551

FIRST MEASUREMENT OF THERADIAL BARYON ACOUSTICFEATURE

PROVIDES VERY PRECISE MEASUREMENT OF H(z)

NOW, WHAT ABOUT NEUTRINOPHYSICS?

WMAP-5 ONLY ~ 1.3 eVWMAP + OTHER 0.67 eV

Komatsu et al., arXiv:0803.0547

WHAT IS THE PRESENT BOUND ON THE NEUTRINO MASS?

GOOBAR, HANNESTAD, MÖRTSELL, TU (JCAP 2006)

NmbAnHwBM ,,,,,,,,, 010 FREE PARAMETERS

WMAP, BOOMERANG, CBISDSS, 2dFSNLS SNI-A

NmbAnHwBM ,,,,,,,,, 010 FREE PARAMETERS

WMAP, BOOMERANG, CBISDSS, 2dFSNLS SNI-A, SDSS BARYONS

sBM QNmbAnH ,,,,,,,,,, 012 FREE PARAMETERS

WMAP-3, BOOMERANG, CBISDSS, 2dF, HSTSNLS SNI-A, SDSS BARYONS

95% @ eV 62.0 m

No BAO

BAO

LY-BAO+LY-

USING THE BAO DATA THE BOUNDIS STRENGTHENED, EVEN FORVERY GENERAL MODELS

IN MORE RESTRICTED MODELS THE BOUND IS STRONGER(BUT BEWARE OF THE PARAMETER DEGENERACIES)

PRELIMINARY RESULT:

WITH WMAP-5 AND RADIAL BAO ALONE ONE FINDS AN UPPER BOUND OF ~ 0.4 – 0.5 eV FOR THE SUM OF NEUTRINO MASSES(STH & HAUGBØLLE, ARXIV:0812.????)

THIS IS A VERY ROBUST RESULT AND VERY INSENSITIVETO MODEL SPACE SELECTION!

ADDITIONAL RELATIVISTIC ENERGY DENSITY

COMPARISON WITHSH & RAFFELT ’04

,0

extraSM,eff

NN

COULD BY CAUSED BY A NUMBER OF DIFFERENT EFFECTS

ADDITIONAL PARTICLE SPECIES

DECAY OF HEAVY SPECIES

NEUTRINO CHEMICAL POTENTIAL

…..

USING WMAP3+SDSS-LRG+SNI-A

C.L.) (95% 9.3 0.26.1

N

HAMANN, STH, RAFFELT, WONG arXiv:0705.0979 (JCAP)

IS EXCLUDED AT ABOUT 5 SIGMA!0N

THIS RESULT IS CONSISTENT WITH WMAP-5

C.L.) (68% 4.4 4.14.1

N (WMAP-5 ONLY)

ALSO DE BERNARDIS ET AL 2008, HAMANN, LESGOURGUES & MANGANO 2008SELJAK, SLOSAR & MCDONALD 2007

WHAT IS IN STORE FOR THE FUTURE?

BETTER CMB TEMPERATURE AND POLARIZATIONMEASUREMENTS (PLANCK)

LARGE SCALE STRUCTURE SURVEYS AT HIGH REDSHIFT

MEASUREMENTS OF WEAK GRAVITATIONAL LENSINGON LARGE SCALES

Distortion of background images by foreground matter

Unlensed Lensed

WEAK LENSING – A POWERFUL PROBE FOR THE FUTURE

H

drPa

gHC m

0

2

240 ),/(

)(

16

9

H

dng

0

''

)'()'(2)(

FROM A WEAK LENSING SURVEY THE ANGULAR POWER SPECTRUMCAN BE CONSTRUCTED, JUST LIKE IN THE CASE OF CMB

),/( rP MATTER POWER SPECTRUM (NON-LINEAR)

WEIGHT FUNCTION DESCRIBING LENSINGPROBABILITY

(SEE FOR INSTANCE JAIN & SELJAK ’96, ABAZAJIAN & DODELSON ’03,SIMPSON & BRIDLE ’04)

STH, TU, WONG 2006

STH, TU & WONG 2006 (ASTRO-PH/0603019, JCAP)

THE SENSITIVITY TO NEUTRINO MASS WILL IMPROVE TO < 0.1 eVAT 95% C.L. USING WEAK LENSINGCOULD POSSIBLY BE IMPROVED EVEN FURTHER USING FUTURELARGE SCALE STRUCTURE SURVEYS

FUTURE SURVEYS LIKE LSST WILL PROBE THE POWER SPECTRUM TO ~ 1-2 PERCENT PRECISION

WE SHOULD BE ABLE TO CALCULATE THE POWER SPECTRUM TO AT LEAST THE SAME PRECISION!

”LSST” ERROR BARS

-1

512 h-1 Mpc

z = 0

z = 4

EVOLUTION OF NEUTRINO DENSITY FIELD

mP

P

6.9~

FULL NON-LINEAR

mP

P

8~

LINEAR THEORY

Brandbyge, STH, Haugbølle, Thomsen, arXiv:0802.3700 (ApJ)

NON-LINEAR EVOLUTION PROVIDES AN ADDITIONAL AND VERY CHARACTERISTIC SUPPRESSION OF FLUCTUATION POWER DUE TO NEUTRINOS (COULD BE USED AS A SMOKING GUN SIGNATURE)

LIGHT NEUTRINOS ARE ALMOST IMPOSSIBLE TO FOLLOW AT HIGH ZBECAUSE OF THERMAL NOISE

SOLUTION: FOLLOW NEUTRINOS USING LINEAR THEORY WITH A GRID-BASED METHOD, SIMULTANEOUSLY WITH THE CDM / BARYONN-BODY SOLVER

BRANDBYGE & STH 2008 (IN PREPARATION)

eV 6.0m

DIFFERENCE BETWEEN GRID AND PARTICLE METHOD

eV 2.1m eV 3.0m

THIS METHOD WORKS FOR REALISTIC NEUTRINO MASSES (BELOW0.5-0.6 eV) AT BETTER THAN 0.5% PRECISION

THE COMPUTATIONAL SPEED IS ESSENTIALLY THE SAME AS FOR A PURE CDM SIMULATION (FACTOR ~ 10 OR MORE FASTER THAN WITHNEUTRINOS AS PARTICLES)

THE GRID METHOD IS NOT USEFUL FOR CALCULATING THE LOCALRELIC NEUTRINO DENSITYFOR THIS THE 1-PARTICLE BOLTZMANN EQUATION SHOULD BE USED(RINGWALD & WONG 2004, STH, RINGWALD, TU & WONG 2005)

CDM -PARTICLE -GRID

z = 49

z = 4

z = 0

z = 49

z = 4

z = 0

WONG 2008

FOR RELATIVELY SMALL NEUTRINO MASSES THE RESULTS CAN BE REPRODUCED USING HIGHER ORDER PERTURBATION THEORYFOR SCALES UP TO k ~ 0.1 h / Mpc (SAITO ET AL. 2008, WONG 2008)THESE CALCULATIONS ALSO ASSUME THAT NEUTRINO STRUCTURESARE LINEAR

CONCLUSIONS

NEUTRINO PHYSICS IS PERHAPS THE PRIME EXAMPLE OF HOW TO USE COSMOLOGY TO DO (ORDINARY) PARTICLE PHYSICS

THE BOUND ON NEUTRINO MASSES IS SIGNIFICANTLYSTRONGER THAN WHAT CAN BE OBTAINED FROM DIRECT EXPERIMENTS, ALBEIT MUCH MORE MODEL DEPENDENT

FUTURE OBSERVATIONS WILL CONTINUE TO IMPROVE THESENSITIVITY TO NEUTRINO PROPERTIES