1. Latest Results from WMAP: Three-year Observations
Eiichiro Komatsu (UT Austin)
Univ.
February 7, 2007

2. Night Sky in Optical (~0.5nm)

3. Night Sky in Microwave (~1mm)

4. A. Penzias & R. Wilson, 1965

5. Helium Superfluidity
T = 2.17 K
CMB
T = 2.73 K

6. COBE/DMR, 1992
Isotropic?
CMB is anisotropic! (at the 1/100,000 level)

8. COBE to WMAP COBE 1989 Press Release from the Nobel Foundation WMAP
[COBE’s] measurements also marked the inception of cosmology as a precise science. It was not long before it was followed up, for instance by the WMAP satellite, which yielded even clearer images of the background radiation.
WMAP
WMAP
2001

9. So, It’s Been Three Years Since The First Data Release in 2003
So, It’s Been Three Years Since The First Data Release in What Is New Now?

10. CMB is not only anisotropic, but also polarized.
POLARIZATION DATA!!
CMB is not only anisotropic, but also polarized.

11. The Wilkinson Microwave Anisotropy Probe
A microwave satellite working at L2
Five frequency bands
K (22GHz), Ka (33GHz), Q (41GHz), V (61GHz), W (94GHz)
Multi-frequency is crucial for cleaning the Galactic emission
The Key Feature: Differential Measurement
The technique inherited from COBE
10 “Differencing Assemblies” (DAs)
K1, Ka1, Q1, Q2, V1, V2, W1, W2, W3, & W4, each consisting of two radiometers that are sensitive to orthogonal linear polarization modes.
Temperature anisotropy is measured by single difference.
Polarization anisotropy is measured by double difference. POLARIZATION DATA!!

12. WMAP Spacecraft 60K 90K 300K upper omni antenna back to back
line of sight
Gregorian optics,
1.4 x 1.6 m primaries
60K
passive thermal radiator
focal plane assembly
feed horns
secondary
90K
reflectors
thermally isolated
instrument cylinder
300K
warm spacecraft with:
- instrument electronics
medium gain antennae
- attitude control/propulsion
- command/data handling
deployed solar array w/ web shielding
- battery and power control
MAP990422

13. WMAP Focal Plane 10 DAs (K, Ka, Q1, Q2, V1, V2, W1-W4)
Beams measured by observing Jupiter.

14. WMAP Three Year Papers

15. K band (22GHz)

16. Ka Band (33GHz)

17. Q Band (41GHz)

18. V Band (61GHz)

19. W Band (94GHz)

20. The Angular Power Spectrum
CMB temperature anisotropy is very close to Gaussian (Komatsu et al., 2003); thus, its spherical harmonic transform, alm, is also Gaussian.
Since alm is Gaussian, the power spectrum:
completely specifies statistical properties of CMB.

21. WMAP 3-yr Power Spectrum

22. What Temperature Tells Us
Distance to z~1100
Baryon-to-Photon Ratio
Dark Energy/
New Physics?
Matter-Radiation Equality Epoch

23. ns: Tilting Spectrum
ns>1: “Blue Spectrum”

24. ns: Tilting Spectrum
ns<1: “Red Spectrum”

25. CMB to Cosmology Today’s Highlight! Constraints on Inflation Models
Low Multipoles (ISW)
&Third
Baryon/Photon Density Ratio
Today’s Highlight!
Constraints on Inflation Models

26. CMB: The Most Distant Light
CMB was emitted when the Universe was only 380,000 years old. WMAP has measured the distance to this epoch. From (time)=(distance)/c we obtained  0.16 billion years.

27. K Band (23 GHz)
Dominated by synchrotron; Note that polarization direction is perpendicular to the magnetic field lines.

28. Ka Band (33 GHz)
Synchrotron decreases as n-3.2 from K to Ka band.

29. Q Band (41 GHz)
We still see significant polarized synchrotron in Q.

30. V Band (61 GHz)
The polarized foreground emission is also smallest in V band. We can also see that noise is larger on the ecliptic plane.

31. W Band (94 GHz)
While synchrotron is the smallest in W, polarized dust (hard to see by eyes) may contaminate in W band more than in V band.

32. Polarization Mask
fsky=0.743

33. Jargon: E-mode and B-mode
Seljak & Zaldarriaga (1997); Kamionkowski, Kosowsky, Stebbins (1997)
Jargon: E-mode and B-mode
Polarization has directions!
One can decompose it into a divergence-like “E-mode” and a vorticity-like “B-mode”.
E-mode
B-mode

34. Polarized Light Un-filtered
Polarized Light Filtered

35. Physics of CMB Polarization
Thomson scattering generates polarization, if and only if…
Temperature quadrupole exists around an electron
Where does quadrupole come from?
Quadrupole is generated by shear viscosity of photon-baryon fluid.
electron
isotropic
no net polarization
anisotropic
net polarization

36. Boltzmann Equation
Temperature anisotropy, Q, can be generated by gravitational effect (noted as “SW” = Sachs-Wolfe, 1967)
Linear polarization (Q & U) is generated only by scattering (noted as “C” = Compton scattering).
Circular polarization (V) is not generated by Thomson scattering.

37. Primordial Gravity Waves
Gravity waves also create quadrupolar temperature anisotropy -> Polarization
Most importantly, GW creates B mode.

38. Power Spectrum
Scalar T
Tensor T
Scalar E
Tensor E
Tensor B

39. Polarization From Reionization
CMB was emitted at z~1100.
Some fraction of CMB was re-scattered in a reionized universe.
The reionization redshift of ~11 would correspond to 365 million years after the Big-Bang. e- e- e- e- e- e-
IONIZED
z=1100, t～1 e- e- e- e- e-
NEUTRAL
First-star formation
z～11, t～0.1
REIONIZED e- e- e- e-
z=0

40. Measuring Optical Depth
Since polarization is generated by scattering, the amplitude is given by the number of scattering, or optical depth of Thomson scattering:
which is related to the electron column number density as

41. Temperature Damping, and Polarization Generation2
“Reionization Bump”

43. Masking Is Not Enough: Foreground Must Be Cleaned
Outside P06
EE (solid)
BB (dashed)
Black lines
Theory EE
tau=0.09
Theory BB
r=0.3
Frequency = Geometric mean of two frequencies used to compute Cl
Rough fit to BB FG in 60GHz

44. Clean FG Only two-parameter fit! Dramatic improvement in chi-squared.
The cleaned Q and V maps have the reduced chi-squared of ~1.02 per DOF=4534 (outside P06)

45. 3-sigma detection of EE.
The “Gold” multipoles: l=3,4,5,6.
BB consistent with zero after FG removal.

46. Parameter Determination (ML): First Year vs Three Years
(w/SZ)
(w/o SZ)
The simplest LCDM model fits the data very well.
A power-law primordial power spectrum
Three relativistic neutrino species
Flat universe with cosmological constant
The maximum likelihood values very consistent
Matter density and sigma8 went down slightly

47. Parameter Determination (Mean): First Year vs Three Years
(w/SZ)
(w/o SZ)
ML and Mean agree better for the 3yr data.
Degeneracy broken!

48. Tau is Constrained by EE
The stand-alone analysis of EE data gives
tau =
The stand-alone analysis of TE+EE gives
tau =
The full 6-parameter analysis gives
tau = (Spergel et al.; no SZ)
This indicates that the stand-alone EE analysis has exhausted most of the information on tau contained in the polarization data.
This is a very powerful statement: this immediately implies that the 3-yr polarization data essentially fixes tau independent of the other parameters, and thus can break massive degeneracies between tau and the other parameters.

49. Degeneracy Broken: Negative Tilt
Parameter Degeneracy Line from Temperature Data Alone
Polarization Data Nailed Tau

50. Constraints on GW
Our ability to constrain the amplitude of gravity waves is still coming mostly from the temperature spectrum.
r<0.55 (95%)
The B-mode spectrum adds very little.
WMAP would have to integrate for at least 15 years to detect the B-mode spectrum from inflation.

51. What Should WMAP Say About Inflation Models?
Hint for ns<1
Zero GW
The 1-d marginalized constraint from WMAP alone is ns=
GW>0
The 2-d joint constraint still allows for ns=1.

52. What Should WMAP Say About Flatness?
Flatness, or very low Hubble’s constant?
If H=30km/s/Mpc, a closed universe with Omega=1.3 w/o cosmological constant still fits the WMAP data.

53. What Should WMAP Say About Dark Energy?
Not much!
The CMB data alone cannot constrain w very well. Combining the large-scale structure data or supernova data breaks degeneracy between w and matter density.

54. What Should WMAP Say About Neutrino Mass?
3.04)

55. Summary Tau=0.09+-0.03 Understanding of Analysis techniques
Noise,
Systematics,
Foreground, and
Analysis techniques
have significantly improved from the first-year release.
A simple LCDM model fits both the temperature and polarization data very well.
Summary
Tau=
To-do list for the next data release (now working on the 5-year data; operation funded for 8 years)
Understand FG and noise better.
We are still using only 1/2 of the polarization data.
These improvements, combined with more years of data, would further
reduce the error on tau.
Full 3-yr would give delta(tau)~0.02; Full 6-yr would give delta(tau)~0.014
This will give us a better estimate of the tilt, and better constraints on inflation.

56. Low-l TE Data: Comparison between 1-yr and 3-yr
1-yr TE and 3-yr TE have about the same error-bars.
1yr used KaQVW and white noise model
Errors significantly underestimated.
Potentially incomplete FG subtraction.
3yr used QV and correlated noise model
Only 2-sigma detection of low-l TE.

57. High-l TE Data Amplitude Phase Shift
The amplitude and phases of high-l TE data agree very well with the prediction from TT data and linear perturbation theory and adiabatic initial conditions. (Left Panel: Blue=1yr, Black=3yr)

58. High-l EE Data WMAP: QVW combined
When QVW are coadded, the high-l EE amplitude relative to the prediction from the best-fit cosmology is
Expect ~4-5sigma detection from 6-yr data.

59. t1st year vs 3rd year
Tau is almost entirely determined by the EE from the 3-yr data.
TE adds very little.
Dotted: Kogut et al.’s stand-alone tau analysis from TE
Grey lines: 1-yr full analysis (Spergel et al. 2003)

60. Degeneracy Finally Broken: Negative Tilt & Low Fluctuation Amplitude
Temperature Data Constrain “s8exp(-t)”
Degeneracy Line from Temperature Data Alone
Polarization Nailed Tau
Polarization Data Nailed Tau
Lower t
Lower 3rd peak