Latest Results from W Latest Results from W MAP: Three-year Obser MAP: Three-year Obser vations vations

Latest Results from W Latest Results from W

MAP: Three-year Obser MAP: Three-year Obser

vations vations

Eiichiro Komatsu (UT Austin) Eiichiro Komatsu (UT Austin)

Colloquium@Columbia Univ.

Colloquium@Columbia Univ.

February 7, 2007 February 7, 2007

Night Sky in Optical Night Sky in Optical

(~0.5nm) (~0.5nm)

Night Sky in Microwave (~1m Night Sky in Microwave (~1m

m)m)

A. Penzias & R. Wilson, 1965 A. Penzias & R. Wilson, 1965

CMB

T = 2.73 K Helium Supe

rfluidity

T = 2.17 K

COBE/DMR, 1992 COBE/DMR, 1992

•Isotropic?

•CMB is anisotropic! (at the 1/100,000 level)

COBE to WMAP COBE to WMAP

COBE

WMAP

COBE 1989

WMAP 2001

[COBE’s] measurements als o marked the inception of co smology as a precise science . It was not long before it was followed up, for instanc e by the WMAP satellite, whi ch yielded even clearer imag es of the background radiati on.

Press Release from the Nobel Foundatio n

So, It’s Been Three Years Since So, It’s Been Three Years Since

The First Data Release in 2003.

The First Data Release in 2003.

What Is New Now?

What Is New Now?

POLARIZATION DATA!!

POLARIZATION DATA!!

CMB is not only anisotropic, but CMB is not only anisotropic, but

also

also polarizedpolarized..

The Wilkinson Microwave The Wilkinson Microwave

Anisotropy Probe 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!!

WMAPWMAP Spacecraft Spacecraft

MAP990422

thermally isolated instrument cylinder

secondary reflectors

focal plane assembly feed horns back to back Gregorian optics, 1.4 x 1.6 m primaries

upper omni antenna line of sight

deployed solar array w/ web shielding medium gain antennae

passive thermal radiator

warm spacecraft with:

- instrument electronics - attitude control/propulsion - command/data handling - battery and power control

60K

90K

300K

WMAP Focal Plane WMAP Focal Plane

QuickTime˛ Ç∆

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• 10 DAs (K, Ka, Q1, Q2, V1, V2, W1-W4)

• Beams measured by observing Jupiter.

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WMAP Three Year Papers WMAP Three Year Papers

K band (22GHz) K band (22GHz)

Ka Band (33GHz) Ka Band (33GHz)

Q Band (41GHz) Q Band (41GHz)

V Band (61GHz) V Band (61GHz)

W Band (94GHz) W Band (94GHz)

The Angular Power Spectrum The Angular Power Spectrum

• CMB temperature anisotropy is very clos e to Gaussian (Komatsu et al., 2003); t hus, its spherical harmonic transform, alm, is also Gaussian.

• Since alm is Gaussian, the power spectru m:

completely specifies statistical proper ties of CMB.

€

C

= a

a

WMAP 3-yr Power Spectrum WMAP 3-yr Power Spectrum

What Temperature Tells Us What Temperature Tells Us

Distance to z~1100

Baryon- to-Photon Ratio

Matter-Radiation Equality Epoch Dark Energy/

New Physics?

nn_ss: Tilting Spectrum: Tilting Spectrum

nn_ss>1: “Blue Spectru>1: “Blue Spectru m”m”

nn_ss: Tilting Spectrum: Tilting Spectrum

nn_ss<1: “Red Spectrum<1: “Red Spectrum

””

CMB to Cosmology CMB to Cosmology

&Third

Baryon/Photon Density Ratio

Low Multipoles (ISW)

Constraints on Inflation Models Today’s Highlight!

CMB: The Most Distant Light CMB: The Most Distant Light

CMB was emitted when the Universe was only 380,000 years ol d. WMAP has measured the distance to this epoch. From (time)

=(distance)/c we obtained 13.73  0.16 billion years.

K Band (23 GHz) K Band (23 GHz)

Dominated by synchrotron; Note that polarization direction is perpendicular to the magnetic field lines.

Ka Band (33 GHz) Ka Band (33 GHz)

Synchrotron decreases as ^-3.2 from K to Ka band.

Q Band (41 GHz) Q Band (41 GHz)

We still see significant polarized synchrotron in Q.

V Band (61 GHz) 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) 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 Polarization Mask

f_sky=0.743

Jargon: E-mode and B-mode 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

Seljak & Zaldarriaga (1997); Kamionkowski, Kosowsky, Stebbins (1997)

Polarized Light Filtered

Polarized Light Un-filtered

Physics of CMB Polarization 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

anisotropic

no net polarization

net polarization

Boltzmann Equation Boltzmann Equation

• Temperature anisotropy, , can be generated by gravi tational effect (noted as “SW” = Sachs-Wolfe, 1967)

• Linear polarization (Q & U) is generated only by scat tering (noted as “C” = Compton scattering).

• Circular polarization (V) is not generated by Thomson scattering.

Primordial Gravity Waves Primordial Gravity Waves

• Gravity waves also create quadrupolar temperature anisotropy -> Polarization

• Most importantly, GW creates B mode.

Power Spectrum Power Spectrum

Scalar T

Tensor T

Scalar E Tensor E

Tensor B

Polarization From Reionizati Polarization From Reionizati

onon

• CMB was emitted at z~1100.

• Some fraction of CMB was re-scattered in a reion ized universe.

• The reionization redshift of ~11 would correspon d to 365 million years after the Big-Bang.

z=1100,  ～ 1

z ～ 11,  ～ 0.1

First-star formation

z=0 IONIZED

REIONIZED NEUTRAL

e^-

e^- e^- e^-

e^-

e^- e^-

e^- e^-

e^-

e^- e^-

e^- e^- e^-

Measuring Optical Depth 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 Temperature Damping, and

Polarization Generation Polarization Generation

“Reionization Bump”

²

e^-

• Outside P06

– EE (solid) – BB (dashed)

• Black lines

– Theory EE

• tau=0.09

– Theory BB

• r=0.3

• Frequency = Geometri c mean of two freque ncies used to comput e Cl

Masking Is Not Enough:

Masking Is Not Enough:

Foreground Must Be Cleaned Foreground Must Be Cleaned

Rough fit to BB FG in 60GHz

Clean FG 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)

BB consistent with zero after FG removal.

3-sigma detection of EE.

The “Gold” mu ltipoles: l=3,4, 5,6.

Parameter Determination (M Parameter Determination (M

L): L):

First Year vs Three Years First Year vs Three Years

• 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

(w/SZ) (w/o SZ)

2.22 0.127 73.2 0.091 0.954 0.236 0.756

Parameter Determination (Mea Parameter Determination (Mea

n): n):

First Year vs Three Years First Year vs Three Years

• ML and Mean agree better for the 3yr data.

– Degeneracy broken!

(w/SZ) (w/o SZ)

2.229 0.128 73.2 0.089 0.958 0.241 0.761

Tau is Constrained by EE 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 implie s that the 3-yr polarization data essentially fixes tau in dependent of the other parameters, and thus can break mass ive degeneracies between tau and the other parameters.

Degeneracy Broken: Negative Tilt Degeneracy Broken: Negative Tilt

Parameter Degeneracy Line from Temperature Data

Alone

Polarization Data Nailed Tau

Constraints on GW 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 What Should WMAP Say

About Inflation Models?

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 What Should WMAP Say

About Flatness?

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 What Should WMAP Say

About Dark Energy?

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 What Should WMAP Say

About Neutrino Mass?

About Neutrino Mass?

3.04 )

• Understanding of

– Noise,

– Systematics, – Foreground, and

• Analysis techniques

• have significantly impro ved from the first-year release.

• A simple LCDM model fits both the temperature and polarization data very w

• To-do list for the next data release (now working on the 5-year data; operatell.

ion 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.

Summary Summary

•Tau=0.09+-0.03

Low-l TE Data: Comparison betwe Low-l TE Data: Comparison betwe

en 1-yr and 3-yr en 1-yr and 3-yr

• 1-yr TE and 3-yr TE have about the same error-bars.

– 1yr used KaQVW and wh ite noise model

• Errors significantly underestimated.

• Potentially incomple te FG subtraction.

– 3yr used QV and corre lated noise model

• Only 2-sigma detecti on of low-l TE.

High-l TE Data High-l TE Data

• The amplitude and phases of high-l TE data agree very we ll with the prediction from TT data and linear perturbat ion theory and adiabatic initial conditions. (Left Pane l: Blue=1yr, Black=3yr)

Phase Shift

Amplitude

High-l EE Data High-l EE Data

• When QVW are coadded, the high-l EE amplitude relative t o the prediction from the best-fit cosmology is 0.95 +- 0.35.

• Expect ~4-5sigma detection from 6-yr data.

WMAP: QVW combined

  1st year vs 3rd year1st year vs 3rd year

• Tau is almost entirely det ermined by the EE from the 3-yr data.

– TE adds very little.

• Dotted: Kogut et al.’s st and-alone tau analysis fro m TE

• Grey lines: 1-yr full anal ysis (Spergel et al. 2003)

Degeneracy Finally Broken:

Degeneracy Finally Broken:

Negative Tilt & Low Fluctuation Negative Tilt & Low Fluctuation

Amplitude Amplitude

Degeneracy Line from Temperature Data Alone

Polarization Data Nailed Tau

Temperature Data Constrain “₈exp(-)”

Lower 

Polarization Nailed Tau

Lower 3rd peak