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….
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