DESY, 30 September 2008 Julien Lesgourgues (CERN & EPFL)

DESY, 30 September 2008

Julien Lesgourgues (CERN & EPFL)

MAIN STREAM

DM = CDM + 3 flavor neutrinos, with 2 or 3 massive eigenstates

2 unknown “cosmological parameters”: m, IH or NH

detectable negligible

SIDE WAYS

Sterile, non-thermal, coupled, decaying, mass-varying, …

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inflation radiation matière énergie noire

??

Effect of Effect of neutrino neutrino

massmass

Effect of neutrino massEffect of neutrino mass Background effect: parameter different from cdm

(also DM today, but radiation in the past)

e.g. increase with fixed dm

decrease cdm

postpone M/R equality

change CMB peak height (and position) and

shape of matter power spectrum P(k)

non-degenerate effect for flat CDM

Effect on perturbations: free-streaming slows down

structure formation

Perfect versus free-streaming fluidPerfect versus free-streaming fluid Perfect fluid = strongly coupled particles with bulk velocity

(in the linear regime: single-valued velocity field)

Free-streaming particles = collisionless particles with f(x,p,t) ≈ f(p,t)

x

p

x

p|v| = |p| /m = velocity dispersion

CDM (WIMPS) in the approximation v << c

HDM (light neutrinos) with 0.01 < v/c < 1

Free-streaming scaleFree-streaming scale

distances

time

a

inflati

on

RADIATIONDOMINATION

eq

MATTERDOMINATION

acausal

causal

RH

perturb

ation wavelength

Free-streaming scaleFree-streaming scale

distances

time

a

inflati

on

RADIATIONDOMINATION

eq

MATTERDOMINATION

acausal

causal

RH

perturb

ation wavelength

maximumcomoving f.s.s.

free-streaming scale

(10-4 eV < m < 1 eV)

nrheavy light

Effect of neutrino massesEffect of neutrino masseson (linear) structure formationon (linear) structure formation

m + H m = 4G m m

expansion gravitational force

Below critical scale, neutrinos contribute to expansion but not

to gravitational force: m(a) slows down, [d ln m / d ln a – 1]

m

. ..

cdm

b

metric

a

J.L.

& S

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Free-streaming and structure Free-streaming and structure formationformation

cdm

b

metric

a

1-3/5fa

J.L.

& S

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Free-streaming and structure Free-streaming and structure formationformation

(f = /m)

A. characteristic shape of matter power spectrum today

Signature of massive neutrinos on Signature of massive neutrinos on P(k)P(k)

P(k) = m2

(today)

kk

Light neutrinos step-like suppression

-8f-8f (from 3% to 60% (from 3% to 60% for 0.05eV to 1eV)for 0.05eV to 1eV)

B. linear growth factor


P(k,a)/a2

=(1+z)2 P(k,z)

kk

sCDM no linear growth factor

sCDM (no DE, no m)



P(k,a)/a2

=(1+z)2 P(k,z)

kk

DE+CDM scale-independent linear growth factor

sCDM (no DE, no m)

DE+CDM (no m)



P(k,a)/a2

=(1+z)2 P(k,z)

kk

DE+CDM+m scale-dependent linear growth factor

sCDM (no DE, no m)

DE+CDM+HDM

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??

currentcurrentobservationobservation

s s till 2007:

best constraints from free-streaming

since WMAP-5yr: background effect

better seen

future: free-streamingmore powerful

mass bounds from 7-parameter fits (MDM = minimal CDM+M)

BoundsBounds o onn neutrino neutrino mass massA

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rom

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. &

S. Past

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s 0

6

(95% CL)

+ SNIa / BAO

+ Ly



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(95% CL)

+ SNIa / BAO

+ Ly

CMB only WMAP5Dunkley et al. 08



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WMAP5 + BAO (SDSS, 2dF) + + SNIa (SNLS, ESSENCE) Komatsu et al. 08

+ SNIa / BAO

+ Ly

+ background (dA, dL)

(95% CL)



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WMAP3 + SDSS-LRG/BAO + 2dF + SNIaHannestad et al. 07, Kristiansen et al. 07

+ SNIa / BAO

+ Ly

+ galaxy power spectrum

(95% CL)



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WMAP3 + SDSS-LRG/BAO + 2dF + SNIaHannestad et al. 07, Kristiansen et al. 07

+ SNIa / BAO

+ Ly

+ galaxy power spectrum

(95% CL)

limited to scales still linear today:

suppression effectin power spectrum P(k)



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WMAP5 + other CMB + SDSS-LRG/BAO + SNIa + SDSS-LyFogli et al. 08

+ SNIa / BAO

+ Lyman- forest

(95% CL)

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futurefuturetechniques techniques

Weak lensing: galaxy Weak lensing: galaxy shearshear

Future:Future:many dedicated many dedicated surveys surveys (CFHTLS, DES, SNAP, (CFHTLS, DES, SNAP, Pan-STARRS, LSST, Pan-STARRS, LSST, Dune, …)Dune, …)

Map of gravitational potentialMap of gravitational potentialprojected along line-of-sightprojected along line-of-sight

COSMOSCOSMOS

Massey et al., Nature 05497, 7 january 2007Massey et al., Nature 05497, 7 january 2007

tomographtomographyy

Weak lensing: CMB Weak lensing: CMB deflectiondeflection

map of gravitational potentialmap of gravitational potentialprojected along line-of-sight, especially around z~3projected along line-of-sight, especially around z~3

Weak lensing: theoretical Weak lensing: theoretical predictionprediction

Lensing spectrum (= convergence spectrum)expected power spectrum of lensing potential

from sources at z ~ 0.2, 0.6, … 3.0(error for LSST)

from sources at z ~ 1100 (CMB)(error for CMBpol)

linea

r

Song & Knox

[astro-ph/0312175]

Weak lensing: theoretical Weak lensing: theoretical predictionprediction

Lensing potential spectrum

Weak lensing: observation with Weak lensing: observation with PlanckPlanck

JL, Perotto, Pastor, PiatPhys.Rev.D73:045021,2006

Weak lensing: forecastsWeak lensing: forecastsJ.L.

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LSST

SNAPPlanck+DUNEKitching et al 08

Perotto et al. 06Lesgourgues et al. 05

Song & Knox 2003

Other promising techniquesOther promising techniques ISW effect induced by free-streaming during MD/DED

Detectable with CMB x LSS cross-correlation

Ichikawa & Takahashi 05

Lesgourgues, Valkenburg & Gaztanaga 07

Cluster redshift surveys

Wang et al. 05

21cm surveys

(21cm line emission by residual cosmic hydrogen after reionization)

Wyithe & Loeb 08

=0.006 eV (differentiate NH / IH) Pritchard & Pierpaoli 08

Ly forests in quasar spectra

Gratton et al. 07

Impact of massive neutrinos on Impact of massive neutrinos on

non-linear gravitational non-linear gravitational clusteringclustering

… … is a crucial to understand, in order to:is a crucial to understand, in order to:

- Extend analysis of galaxy / cluster/ cosmic shear surveys to larger kExtend analysis of galaxy / cluster/ cosmic shear surveys to larger k

- Perform proper analysis of Ly-Perform proper analysis of Ly- / BAO / 21cm data / BAO / 21cm data

- Properly extract / interpret CMB foregrounds (thermal SZ)Properly extract / interpret CMB foregrounds (thermal SZ)

- Precisely address small-scale CDM distribution problem (satellites)Precisely address small-scale CDM distribution problem (satellites)



Brandbyge et al. 0802.3700 [astro-ph]

N-body simulations including thermal velocities



Saito, Takada, Taruya 0801.0607 [astro-ph]

Semi-analytical method (approximation to one-loop order)

z=0



Y.Y.Y.Wong 0809.0693 [astro-ph]

Semi-analytical method (one-loop order)

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?? The end The end

DESY, 30 September 2008 Julien Lesgourgues (CERN & EPFL)

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Transcript of DESY, 30 September 2008 Julien Lesgourgues (CERN & EPFL)