WMAP – 3-year results
Fabio Finelli
INAF/OAB & INAF/IASF-BO
Lauro Moscardini
Dip. Astronomia UniBo
Bologna, 27 Aprile 2006
SOURCES
1. WMAP 1st year papers
2. WMAP 3rd papers
3. A. Lewis, astro-ph/0603753
4. Planck Bluebook, astro-ph/0604069
5. Wayne Hu’s webpage:
http://background.uchicago.edu/whu
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WMAP
• WMAP: spinning (~0.5 rpm),
precessing satellite orbiting L2
• dual Gregorian (1.4×1.6m) mirror
system
• passively cooled to <95K
• radiometers measuring phase and
amplitude of incoming waves
• Proposed in 1995; selected in
1996; launched in june 2001;
possibly 8-years mission
• 13 papers in 2003, 7311 citations
up today
• 4 new papers in march 2006, 160
citations up today
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Channels
• frequencies: 22, 30,
40, 60, 90 GHz (3.3
to 13.6 mm
wavelength)
• resolution: 0.230.93 degrees
• sensitivity: ~35µK
per 0.3×0.3 degree
pixel
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Channels
• frequencies: 22, 30,
40, 60, 90 GHz (3.3
to 13.6 mm
wavelength)
• resolution: 0.230.93 degrees
• sensitivity: ~35µK
per 0.3×0.3 degree
pixel
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Sky Maps
foregrounds:
synchrotron,
dust,
free-free
emission
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Temperature Map
• foreground
subtraction: spectra
differ from the
CMB's Planck
spectrum
• comparison of
signals from
different channels
• fitting of foreground
templates
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Power-Spectrum Analysis
• subtraction of mean
temperature; relative
temperature fluctuations
• expansion into spherical
harmonics; coefficients alm
• power spectrum
Cl=<|alm|2> , related to the
matter power spectrum P(k)
• principal effects:
– Sachs-Wolfe effect
– acoustic oscillations
– Silk damping
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Courtesy by W. Hu
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Mechanisms for anisotropies
gravity: gravitational red- or blue-shift
density: adiabatic process  compression increases T,
while expansion decreases T
velocity: Doppler effect
Different contributions must be summed up
Primary anisotropies: produced on the last scattering surface
Secondary anisotropies: produced along the trajectory to the
observer
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On scales larger than the horizon
(i.e. large angles, small l)
Velocity can be neglected (dipole), microphysics too,
gravity wins against density!
Temperature fluctuations are directly proportional to
the gravitational potential: Sachs-Wolfe effect
Notice: overdensity are colder than average!
Already observed by COBE in 1991!
Good estimates for amplitude and slope of P(k),
but problems of cosmic variance
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The cosmological parameters (I):
the density parameters i
• Matter:  m
• Dark energy:  DE (w  P/ c2=-1 is the
cosmological constant  ; w  -1 is the
quintessence)
• Baryons:  b
• Curvature:  K=1 -   i
• Total:  0 =1-  K
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The cosmological parameters (II):
the spectral parameters
Standard inflationary models predict that primordial
fluctuations are
• Gaussian
• Adiabatic
• Scale invariant, i.e. with logarithmic slope of the
power spectrum n=1: P(k)=A kn
The amplitude A is usually expressed in terms of the
variance computed on a scale of 8 Mpc/h: 8
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The cosmological parameters (III):
the other ones
• The Hubble constant H0 and its redshift evolution:
measures the expansion rate of the universe and enters the
distance definitions
• The optical depth  : it is related to the probability that a
CMB photon with an electron along the trajectory:
dP=ne T c dt=-d 
If there is re-ionization at a given redshift zre, photons are
diffuse  there is a suppression of fluctuations on scales
smaller than the horizon scale at zre (warning: degeneracy
with spectral index n). The higher is zre, the smaller is the
angular scale involved by diffusion.
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Power Spectra and Cosmological Parameters
Varying the baryonic density
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Power Spectra and Cosmological Parameters
Varying the Hubble constant
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Power Spectra and Cosmological Parameters
Varying the matter density
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Power Spectra and Cosmological Parameters
Varying the total density
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CMB Polarisation
• CMB photons have last
been Thomson
scattered
• directional dependence
of Thomson cross
section imprints
polarisation
• polarisation pattern has
similar, but shifted
power spectrum
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Polarisation and Reionisation
• Universe recombined when
CMB formed
• hydrogen was later
reionised
• ionised hydrogen damps
primordial fluctuations
• creates secondary
polarisation
• constraints on reionisation
from temperaturepolarisation and
polarisation power spectra
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Where were we?
CMB anisotropies
WMAP 1st year results (Feb.03): TT & TE
EE detection by DASI (02), CBI (04), CAPMAP (05), Boomerang (05)
Galaxy surveys
2dF: Percival et al. (02), Cole et al. (05).
SDSS: Tegmark et al. (04), Seljak et al. (05).
Ly used heavily in WMAP1, but not in WMAP3:
“… further study is needed if the new values are consistent with
Ly data.” See however Viel et al. (06), Seljak et al. (06) for WMAP3 + Ly
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Issues after WMAP 1st year
High value for 
Sticky points out of the CDM fit
Low amplitude for low multipoles of the Cl pattern
Weird alignment of the l=2,3 of alm
Evidence of running of the spectral index ?
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Will these “waves” in 1st year data persist?
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Temperature WMAP3 plus small scale CMB data
The spectrum is cosmic
variance limited to l=400
(354 1st year)and S/N>1 up
to l=850 (658 1st year)
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Red: WMAP1
Black: WMAP3
Points: ratio of WMAP3
over WMAP1 value
Red line: ratio of window function
WMAP1 over WMAP3
Red: WMAP1 with 06 analysis and
06 windows function
Black: WMAP3
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WMAP1
WMAP3
Anomaly on the octupole alleviated; quadrupole remains low
TE in better agreement with CDM;  is almost half of 1st yr value
Some (but not all) of the sticky points remain
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Lines:
Red: WMAP1
Orange: WMAP1 + CBI +ACBAR
Black: WMAP3
Points:
Grey: WMAP1
Black: WMAP3
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CDM plus  constraints
courtesy from Spergel et al., 2006
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CDM plus  is a good fit to WMAP
courtesy from Hinshaw et al., 2006
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CMB Polarization
Polarization only useful for measuring tau for near future
Polarization probably best way to detect tensors
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Cosmological Parameters: Main WMAP3 parameter results rely on polarization
courtesy from A. Lewis, 2006
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WMAP3 TT with tau = 0.10 ± 0.03 prior (equiv to WMAP EE)
Black: TT+prior
Red: full WMAP
courtesy from A. Lewis, 2006
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Implications for Nucleosynthesis
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
From
=0.170.04 (1st year)
To
=0.090.03 (3 years)
courtesy from Page et al., 2006
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1 e 2 contours:
Light Blue: WMAP1
Red: WMAP1 + CBI +ACBAR
Blue: WMAP3
courtesy from Spergel et al., 2006
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Is Harrison-Zeldovich Ruled out?
ns =1
So:
ns < 1
or tau is high
or there are tensors
or the model is wrong
or we are quite unlucky
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Dark Energy: wDE≠ w = -1
for CMB anisotropies we need
DE perturbations
wDE constant in time
cDE =1
(pDE=c2DE DE+…).
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WMAP 3 years results without DE perturbations are flawed
Effect known since Caldwell,Dave, Steinhardt PRL 1998
Abramo, Finelli, Pereira PRD 2004
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Massive Neutrinos
courtesy from Spergel et al., 2006
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Curvature K≠0
courtesy from Spergel et al., 2006
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Curvature K≠0 plus Dark Energy
courtesy from Spergel et al., 2006
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Gravity Waves
Baldi,Finelli,Matarrese, PRD72 (2005)
rk* = PT(k*)/PS(k*)
r0.002 < 0.55 (2)
r0.002 < 0.28 (2)
WMAP3 only
r0.002 < 1.28 (2)
WMAP1 only
WMAP3 plus SDSS
r0.002 < 1.14 (2)
WMAP1 plus 2dFGRS
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LCDM+
Tensors
No evidence from tensor modes
-is not going to get much better
from TT!
courtesy from A. Lewis, 2006
Single standard scalar field inflation: r = - 8 nT
Leach & Liddle, PRD (2003)
Finelli et al., in preparation (2006)
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WMAP-3 yr twist: SZ
SZ Marginalization
Spergel et al.
Black: SZ marge; Red: no SZ
Slightly LOWERS ns
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CMB lensing and WMAP3
Black: with
red: without
- increases ns
not included in Spergel et al analysis
opposite effect to SZ marginalization
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And Planck?
• to be launched in 2008
• improved frequency
coverage (30-857 GHz) for
improved foreground
subtraction
• improved resolution (>5')
and sensitivity (~µK)
• more accurate polarisation
measurement
• foregrounds!
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Planck vs WMAP:1
courtesy from C. Burigana
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Planck vs WMAP:2
courtesy from C. Burigana
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Planck vs WMAP:3
courtesy from Planck Bluebook, astro-ph/0604069
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Planck vs WMAP:4
courtesy from Spergel et al., 2006
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Planck vs WMAP:5
courtesy from Planck Bluebook, astro-ph/0604069
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