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

Night Sky in Optical (~0.5nm)

Night Sky in Microwave (~1mm)

A. Penzias & R. Wilson, 1965

Helium Superfluidity T = 2.17 K CMB T = 2.73 K

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

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

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 2003. What Is New Now?

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

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!!

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

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

WMAP Three Year Papers

K band (22GHz)

Ka Band (33GHz)

Q Band (41GHz)

V Band (61GHz)

W Band (94GHz)

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.

WMAP 3-yr Power Spectrum

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

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

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

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

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 13.73  0.16 billion years.

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

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

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

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.

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.

Polarization Mask fsky=0.743

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

Polarized Light Un-filtered Polarized Light Filtered

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

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.

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

Power Spectrum Scalar T Tensor T Scalar E Tensor E Tensor B

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

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

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

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

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)

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

Parameter Determination (ML): First Year vs Three Years (w/SZ) (w/o SZ) 2.22 0.127 73.2 0.091 0.954 0.236 0.756 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

Parameter Determination (Mean): First Year vs Three Years (w/SZ) (w/o SZ) 2.229 0.128 73.2 0.089 0.958 0.241 0.761 ML and Mean agree better for the 3yr data. Degeneracy broken!

Tau is Constrained by EE The stand-alone analysis of EE data gives tau = 0.100 +- 0.029 The stand-alone analysis of TE+EE gives tau = 0.092 +- 0.029 The full 6-parameter analysis gives tau = 0.088 +- 0.029 (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.

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

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.

What Should WMAP Say About Inflation Models? Hint for ns<1 Zero GW The 1-d marginalized constraint from WMAP alone is ns=0.96+-0.02. GW>0 The 2-d joint constraint still allows for ns=1.

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.

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.

What Should WMAP Say About Neutrino Mass? 3.04)

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=0.09+-0.03 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.

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.

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)

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 0.95 +- 0.35. Expect ~4-5sigma detection from 6-yr data.

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)

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