Three-Year WMAP Observations: Method and Results

1. Three-Year WMAP Observations: Method and Results Eiichiro Komatsu (UT Austin) Colloquium at U. of Florida October 13, 2006

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

3. POLARIZATION DATA!!

4. WMAP Three Year Papers

5. Full Sky Microwave Map COBE/FIRAS: T=2.725 K Uniform, “Fossil” Light from the Big Bang Cosmic Microwave Background Radiation

6. G. Gamow, 1948

7. Determination of Physical Conditions in the Early Universe n+pD+g

8. Why was it so important? • Gamow has shown that the baryon number density was ~1018 cm-3, when the temperature was 109 K. • It’s ~10-7 cm-3now. What is the temperature now? • Since the baryon number density scales as (radius of the universe)–3 ~(temperature)3, we get for the present-day temperature: • Who calculated this first?

9. R. Alpher & R. Herman, 1949 ~5K ~109 K Deuterium formation Log TIME (sec)

10. A. Penzias & R. Wilson, 1965

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

12. COBE/FIRAS, 1990 Perfect blackbody = Thermal equilibrium = Big Bang

13. COBE/DMR, 1992 Gravity is STRONGER in cold spots: DT/T~F

15. David Wilkinson (1935~2002) • Science Team Meeting, July, 2002 • Plotted the “second point” (3.2cm) on the CMB spectrum • The first confirmation of a black-body spectrum (1966) • Made COBE and MAP happen and be successful • “Father of CMB Experiment” • MAP has become WMAP in 2003

16. The Wilkinson Microwave Anisotropy Probe • A microwave satellite working at L2 • Five frequency bands • K (22GHz), Ka (33GHz), Q (41GHz), V (61GHz), W (94GHz) • 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.

17. WMAP Spacecraft 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: medium gain antennae - instrument electronics - attitude control/propulsion - command/data handling deployed solar array w/ web shielding - battery and power control MAP990422

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

19. WMAP Goes To L2 0.010 • June 30, 2001 • Launch • Phasing loop • July 30, 2001 • Lunar Swingby • October 1, 2001 • Arrive at L2 • October 2002 • 1st year data • February 11, 2003 • 1st data release • October 2003 • 2nd year data • October 2004 • 3rd year data • March 16, 2006 • 2nd data release 0.005 Earth Y (AU) L2 0.000 -0.005 -0.010 1.000 1.005 1.010 X (AU)

20. K band (22GHz)

21. Ka Band (33GHz)

22. Q Band (41GHz)

23. V Band (61GHz)

24. W Band (94GHz)

25. 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.

26. WMAP 3-yr Power Spectrum

27. Physics of CMB Anisotropy • SOLVE GENERAL RELATIVISTIC BOLTZMANN EQUATIONS TO THE FIRST ORDER IN PERTURBATIONS

28. Use temperature fluctuations, Q=DT/T, instead off: Expand the Boltzmann equation to the first order in perturbations: where describes the Sachs-Wolfe effect: purely GR fluctuations.

29. For metric perturbations in the form of: Newtonian potential Curvature perturbations the Sachs-Wolfe terms are given by wheregis the directional cosine of photon propagations. • The 1st term = gravitational redshift • The 2nd term = integrated Sachs-Wolfe effect h00/2 (higher T) Dhij/2

30. Small-scale Anisotropy (<2 deg) • When coupling is strong, photons and baryons move together and behave as a perfect fluid. • When coupling becomes less strong, the photon-baryon fluid acquires shearviscosity. • So, the problem can be formulated as “hydrodynamics”. (c.f. The Sachs-Wolfe effect was pure GR.) Collision term describing coupling between photons and baryons via electron scattering.

31. Boltzmann Equation to Hydrodynamics • Multipole expansion • Energy density, Velocity, Stress Monopole: Energy density Dipole: Velocity Quadrupole: Stress

32. CONTINUITY EULER Photon-baryon coupling Photon Transport Equations f2=9/10 (no polarization), 3/4 (with polarization) FA = -h00/2, FH = hii/2 tC=Thomson scattering optical depth

33. Baryon Transport Cold Dark Matter

34. The Strong Coupling Regime SOUND WAVE!

35. The Wave Form Tells Us Cosmological Parameters Higher baryon density • Lower sound speed • Compress more • Higher peaks at compression phase (even peaks)

36. Weighing Dark Matter wheregis the directional cosine of photon propagations. • The 1st term = gravitational redshift • The 2nd term = integrated Sachs-Wolfe effect h00/2 (higher T) Dhij/2 During the radiation dominated epoch, even CDM fluctuations cannot grow (the expansion of the Universe is too fast); thus, dark matter potential gets shallower and shallower as the Universe expands --> potential decay --> ISW --> Boost Cl.

37. Weighing Dark Matter • Smaller dark matter density • More time for potential to decay • Higher first peak

38. Measuring Geometry Sound cross. length • W=1 • W<1

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

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

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

42. 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.

43. 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.

44. Polarization Mask fsky=0.743

45. Seljak & Zaldarriaga (1997); Kamionkowski, Kosowsky, Stebbins (1997) Jargon: E-mode and B-mode • Polarization is a rank-2 tensor field. • One can decompose it into a divergence-like “E-mode” and a vorticity-like “B-mode”. E-mode B-mode

46. Polarized Light Un-filtered Polarized Light Filtered

47. Physics of CMB Polarization • Thomson scattering generates polarization, 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

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

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

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