Alessandro MelchiorriUniversita’

di Roma, “La Sapienza”

INFN, Roma-1

Neutrino Telescopes, Venice, 13 March 2009

Cosmic

Microwave

Background Anisotropies

and Polarization

Current

Status and Perspectives

(on neutrino physics)

The Cosmic Microwave Background

Discovered

By

Penzias

and Wilson in1965.It

is

an

image

of the universe

at the

time of recombination

(nearbaryon-photons

decoupling), when

the

universe

was

just a few thousand

yearsold (z~1000).The CMB frequency

spectrum

is

a perfect

blackbody

at T=2.73 K:this

is

an

outstanding

confirmation

of the hot big bang model.

Uniform...

Dipole...

Galaxy (z=0)

The Microwave Sky

COBE

Imprint

left

by

primordialtiny

density inhomogeneities

(z~1000)..

2121 )12(

21

PCTT

TT

NASA/GSFCChuck Bennett (PI)Michael GreasonBob Hill Gary HinshawAl KogutMichele LimonNils OdegardJanet WeilandEd Wollack

PrincetonChris Barnes Norm JarosikEiichiro KomatsuMichael Nolta

UBCMark Halpern

ChicagoStephan Meyer

BrownGreg Tucker

UCLANed Wright

Science Team:

Wilkinson Microwave Anisotropy ProbeA partnership between NASA/GSFC and Princeton

Lyman PageDavid Spergel

B03 Polarization Power Spectra

[MacTavish

et al. 2005]

New Results

fromQUAD: Astrophysical

Journal

692 (2009) 1247-1270

Temperature Angular spectrum varies with tot

b

chns, …

We

can measure

cosmological

parameters

with

CMB !

How to get a bound on a cosmological parameter

DATA

Fiducial

cosmological model:(Ωb

h2 , Ωm

h2 , h , ns , τ, Σmν

)

PARAMETERESTIMATES

Dunkley

et

al., 2008

CMB Anisotropies

Four

mechanisms

are responsable

for

CMB anisotropies:

• Gravity

(Sachs-Wolfe

effect)

• Intrinsic

(Adiabatic) Fluctuations

• Doppler effect

• Time-Varying

Potentials

(Integrated

Sachs-Wolfe

Effect)

dzHenzgnTT

0

1b0 v

GravityAdiabatic Doppler ISW

Assuming

we

have: recDirac zzzg

dzHennTT

reczz

0

1b0 v

Neglecting

the ISW term

(potential

constant

with

time), and working in Fourier space we

have:

RkcR recsrec cos)31(

31

0

where

43 bR

recsb kcvnrec

sin31

Why

oscillations

?

Hu, Sugiyama, Silk, Nature 1997, astro-ph/9604166

General

theoretical

prediction: Oscillations

in the angular

power spectrum.However

we

don’t have

an

harmonic

series

of peaks

! There

is

a scale-dependent

Shift

due to

pre-recombination

effects

(Early

Integrated

Sachs Wolfe).

)( mam mll

1''

m

mmm l

l

Data (and properlyComputed

theory)

See

e.g. Corasaniti

& MelchiorriPhys. Rev. D 77, 103507 (2008)

Pre-recombination

effects

from

radiation

(Early

ISW) are suggested

from

WMAP5 !

Harmonic

series

Integrated Sachs-Wolfe effectwhile most cmb

anisotropies arise on the last scattering surface, some

may be induced by passing through a time varying gravitational potential before and after recombination.

when does the linear potential change?

22 4 aG Poisson’s equation

• changes during radiation

domination or if radiation componentis not negligible. (Early ISW)• decays after curvature or dark energy come to dominate (z~1)(Late ISW).

Radiation

Photons

Neutrinos

Cosmological NeutrinosNeutrinos

are in equilibrium

with

the primeval

plasma through weak

interaction reactions. They

decouple

from

the plasma at a temperature

MeVTdec 1We

then

have

today

a Cosmological

Neutrino Background at a temperature:

eVkTKTT 43/1

1068.1945.1114

With

a density of:

33,

32 1121827.0)3(

43 cmTnTgn

kkfff

That, for

massless

neutrinos

the total radiation

energy

density is:

v

effv

R NTT

4

871

Effect of Radiation in the CMB: Early ISWChanging the number of neutrinos (assuming them as massless) shifts the epoch of equivalence, increasing the Early ISW:

Latest

results

from

WMAP5 Neff

>0 at 95 % c.l.

fromCMB DATA alone (Komatsu

et

al., 2008).

First

evidence

for

a neutrino background from

CMB data

Komatsu

et

al.2008WMAP5 paper

Massless

neutrinos, like photons, have anisotropies which follow a Liouville

differential equation:

02

kjjkii h

xat

As in the case of photons, these anisotropies can be computed integrating a hierarchy of differential equations.

Can we

see

them

?

Hu

et

al., astro-ph/9505043

Not

directly!But

we

can see

the

effects

on theCMB angularspectrum

!

CMB photons

seethe NB anisotropiesthrough gravity.

Hu

et

al., astro-ph/9505043

The Neutrino anisotropies

can be

parameterized

through the “speed viscosity”

cvis. which

controls

the relationship

between

velocity/metric

shear

and anisotropic

stress in the NB.

Hu, Eisenstein, Tegmark

and White, 1999

Current

CMB+SLOANdata provide

evidence

at 2.4

for

anisotropiesin the NeutrinoBackground.Standard Model o.k.R. Trotta, AMPhys

Rev

Lett.

95 011305 (2005)

But

that

was

with

WMAPFirst year…

Komatsu

et

al.2008WMAP5 paper

F. De Bernardis

et al, JCAP06(2008)013

Latest

analysis

including

WMAP5 year…more

or less

the same

r

F. De Bernardis

et al, JCAP06(2008)013

Evidence

for

CNB not

due to

neutrino anisotropies

!

Age of the Universe

Gyrs23.084.138.91

04

100

rm aaadaHt

CMB data are able

to

tightly

constrain

the age

of the Universe

(see

e.g. Ferreras, AM, Silk, 2002). For

WMAP+all

and LCDM:

Spergel

et

al., 2007

Direct and “modelindependent”age

aestimates

have

muchlargererror bars

!

Not

so goodfor

constraining

DE

Gyrs3.083.13

(if

w is

included)

Age of the Universe

effrel N

…however

the WMAP constrain

is

model dependent. Key parameter: energy

density in relativistic

particles.

Gyrs8.13 3.22.30

t

Error barson agea factor

10

larger

whenExtra Relativisticparticles

are

Included.

F. De Bernardis, A. Melchiorri, L. Verde, R. Jimenez, JCAP 03(2008)020

F. De Bernardis, A. Melchiorri, L. Verde, R. Jimenez, JCAP 03(2008)020

Independent

age

aestimates

are important.Using

Simon, Verde, Jimenez

aestimates

plus WMAP we

get:

1.17.3 effN

F. De Bernardis, A. Melchiorri, L. Verde, R. Jimenez, JCAP 03(2008)020

Cosmological

Bounds on

Neutrino Mass

Fogli et

al., arXiv:0805.2517 , Phys.Rev.D78:033010,2008 New WMAP5+ACBAR data improves

CMB constraint

Planck

Satellite in Kouru,French

Guyana

Planck

Launch: April

12 2009: stay tuned

Planck

Launch: April

12 2009: stay tuned(two

weeks

delay

April

29 ?)

First Hadronic

collisions

at LHC….