Latest Results from WMAPWMAP: Three-year Observations

Eiichiro Komatsu

University of Texas at Austin

January 24, 2007

WMAP Three Year Science Team

NASA/GSFCChuck Bennett [PI] (-> JHU)

Mike GreasonBob Hill Gary Hinshaw [CoI]Al KogutMichele LimonNils OdegardJanet WeilandEd Wollack

PrincetonChris Barnes (->MS)

Rachel Bean (->Cornell)

Olivier Dore (-> CITA)

Norm Jarosik [CoI]

Eiichiro Komatsu (->Texas)Mike Nolta (-> CITA)Lyman Page [CoI]Hiranya Peiris (-> Chicago)David Spergel [CoI]Licia Verde (-> U. Penn)

ChicagoSteve Meyer [CoI]

UCLANed Wright [CoI]

BrownGreg Tucker

UBCMark Halpern

Night Sky in Optical (~0.5nm)

Night Sky in Microwave (~1mm)

A. Penzias & R. Wilson, 1965

R. Dicke and J. Peebles, 1965

3.5KNOW

P. Roll and D. Wilkinson, 1966

D.Wilkinson

“The Father of CMB Experiment”

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• “The Father of CMB Experiment”• MAP has become WMAP in 2003

COBE/DMR, 1992

•Isotropic?

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

COBE to WMAPCOBE

WMAP

COBE1989

WMAP2001

[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.

Press Release from the Nobel Foundation

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.

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!!

Microwave Sky (minus the mean temperature) as seen by WMAP

WMAP 3-yr Power Spectrum

What Temperature Tells Us

Distance to z~1100

Baryon-to-Photon Ratio

Matter-Radiation Equality Epoch

Dark Energy/New Physics?

R. Sachs and A. Wolfe, 1967

•SOLVE GENERAL RELATIVISTIC BOLTZMANN SOLVE GENERAL RELATIVISTIC BOLTZMANN EQUATIONS TO THE FIRST ORDER IN PERTURBATIONSEQUATIONS TO THE FIRST ORDER IN PERTURBATIONS

Boltzmann Equation

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

• Linear polarization (Q & U) cannot be generated gravitationally. It is generated only by scattering (noted as “C” = Compton scattering).

• Circular polarization (V) would not be generated.

For metric perturbations in the form of:

jiijij dxdxhdhads 2

0022 1

the Sachs-Wolfe terms are given by

where is the directional cosine of photon propagations.

Newtonian potential Curvature perturbations

1. The 1st term = gravitational redshift

2. The 2nd term = integrated Sachs-Wolfe effect

h00/2

hij/2

(higher T)

CMB to Cosmology

&Third

Baryon/Photon Density Ratio

Low Multipoles (ISW)

Constraints on Inflation Models

ns: Tilting Spectrum

nnss>1: “Blue Spectrum”>1: “Blue Spectrum”

ns: Tilting Spectrum

nnss<1: “Red Spectrum”<1: “Red Spectrum”

News from 3-yr data is… POLARIZATION MAP!

Composition of Our Universe Determined by WMAP 3yr

DarkEnergy

DarkMatter

Baryons

76%

20%

4%

Mysterious “Dark Energy” occupies 75.93.4% of the total energy of the Universe.

Parameter Determination (ML): 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 (Mean): 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

Degeneracy Broken: Negative Tilt

Parameter Degeneracy Line from Temperature Data Alone

Polarization Data Nailed Tau

No Detection of Gravity Waves (yet)• 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 >15 years to detect the B-mode spectrum from inflation.

r = Gravity Wave Amplitude / Scalar Curvature Fluctuations

What Should WMAP Say About Inflation? (See W.Kinney’s Talk)

Hint for ns<1

Zero GW (r=0) The 1-d marginalized constraint from WMAP alone is ns=0.96+-0.02.

Non-zero GWThe 2-d joint constraint still allows for ns=1.

What Should WMAP Say About Flatness of the Universe?

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.

• Understanding of– 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.

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

• 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 (hopefully)

• This will give us a better estimate of the tilt, and better constraints on inflation.

Summary

•Tau=0.09+-0.03

What Should WMAP Say About Neutrinos?

3.04)