TheWILKINSON MICROWAVE ANISOTROPY PROBE

Mission

(COBE announcement, 4/92)

Dave Wilkinson

NASA/GSFCChuck Bennett (PI)Bob Hill Gary Hinshaw Al KogutMichele LimonNils OdegardJanet WeilandEd Wollack

PrincetonChris Barnes Norm Jarosik Eiichiro KomatsuMichael Nolta

UBCMark Halpern

ChicagoStephan Meyer

BrownGreg Tucker

UCLANed Wright

Science Team:

WMAPA partnership between NASA/GSFC and Princeton

Lyman PageHiranya PeirisDavid SpergelLicia Verde

WMAP Spacecraft

MAP990422

thermally isolatedinstrument cylinder

secondaryreflectors

focal plane assemblyfeed horns

back to backGregorian 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 Instrument drawing

RXB @ 290K

FPA@ 90K

A-side B-side

Measured in flight Modeled

In-flight beam maps from Jupiter. Scan symmetrizes them!

Sidelobe Pickup Maps

15μK rms 2μK rms

0.3μK rms 0.5μK rms

2μK rms

Off plane…..

Q,V,Wpol<<1μK rms

Why low 1/f ?

One of 20Spin rate

A-B-A-B B-A-B-A

Differential design...

….mK thermal stability

Amplifiers from NRAO, M. Pospieszalski design

Noise in maps Gaussian over five decades. Jarosik et al.

Physical temperature of receivers

20μK

−20μK

Sun referenced azimuth

WMAP computer error rate

GOES proton flux

Physical temperature of primary

Limon et al.

Trajectory

100 days to L2, 1.5e6 km from Earth.

Lunar swingbyPhasing loops

Co-rotating potential.

Official arrival date: Oct 1, 2001

Scan pattern Need to scan in a criss-cross pattern to avoid striping and to minimize pixel-pixel correlations. (Wright and Tegmark)

1) Phase switch 2.5

KHz

2) Spin at 2.2 min/rev

3)Precess through

30% of the sky in 1

hour.

4) Full sky every 6

months.

Four fold switching:

Precession Rate: 1rph22.5° half-angle

A-sideLine of sight

B-sideLine of sight

Spin rate 0.464 rpm

MAP at L2

Earth

Sun

1.5 x 108 km

North Ecliptic Pole

South Ecliptic Pole

+90° +45°

First Year Coverage

Map

Of special importance...

1) Remove dipole from time ordered data.

2) Bin 40 days of data synchronously with the Sun position.

3) Find: ΔTrms<0.14μK

There are no corrections for spin synchronous artifacts!

COBE-WMAP Comparison

COBE

WMAP

Temperature (µK)+200-200

Temperature (µK)+200-200

COBE-WMAP Comparison

Difference

Noise

Temperature (µK)+100-100

Internal Linear Combination CMB

Temperature (µK)+200-200

SUM DIFFERENCE

Q

V

W

Passband mismatch

Less coverage

K and Ka for foregrounds

Best fit model

Prediction based on TT, no free params.

cosmic variance

Temperature

Temperature-polarization

1 deg

85% of sky

The Future:

•Systematics•Refined parameters•Lensing •Polarization

http://lambda.gsfc.nasa.govData available through:

WMAP is funded for 4 y.

Satellites & BalloonPLANCK & CMBPOL

Large ground based CMB telescopes

Boomerang...

ACT, APEX, SPT, …..

END