CMB Anisotropy thru WMAP III

Ned Wright, UCLA

True Contrast CMB Sky

33, 41 & 94 GHz as RGB, 0-4 K scale

Enhanced Contrast:

• Conklin 1969 - 2• Henry 1971 - 3• Corey & Wilkinson

1976 - 4• Smoot et al. 1977 - 6

A Big Media Splash in 1992:

Prof. Stephen Hawking of Cambridge University, not usually noted for overstatement, said: “It is the discovery of the century, if not of all time.”

25 April 1992

Animated View of Inflation

• Quantum fluctuations occur uniformly throughout space-time

• Future light cones have radii of (c/H)[exp(Ht)-1]

COBE DMR vs EPAS

“Chi-by-eye” suggests that the “Equal Power on All Scales” prediction of inflation is correct.

Sachs-Wolfe Effect: Gravitational potential = 3c2T/T Leads to

Large-Scale Structure

Prediction of Acoustic Peaks in CDM

Bond & Efstathiou, 1987, MNRAS, 226, 655-687

Two Fluids in the Early Universe• Most of the mass is dark matter

– 80-90% of the density– Zero pressure– Sound speed is zero

• The baryon-photon fluid– baryons are protons & neutrons = all ordinary

matter– energy density of the photons is bigger than c2

times the density of baryons– Pressure of photons = u/3 = (1/3) c2

– Sound speed is about c/3 = 170,000 km/sec

Traveling Sound Wave: cs c/3

Stay at home Dark Matter

Interference at last scattering• For the wavelength illustrated [1/2 period

between the Big Bang and recombination], the denser = hotter effect and potential well = cooler effect have gotten in phase.

• For larger wavelengths they are out of phase at recombination:

Spherical Harmonic Decomposition

Many parameters to measure

Careful measurements of the power at various angular scales can determine the Hubble constant, the matter density, the baryon density, and the vacuum density.

COBE View was Blurry

Pre-WMAP Power Spectrum

Flat, n=1; b = 0.021, c = 0.196, Ho = 47; b = 0.022, c = 0.132, Ho = 68, = 2/3

Calibration Uncertainties• Each experiment (except for COBE and

later WMAP) has amplitude uncertainty of several percent that is correlated across all the data from that experiment.

• I have done fits and plots that solve separately for calibration adjustment “nuisance parameters” which are included in the 2 but not in the errorbars.

• Combining data from many experiments gives a “flexible” observed spectrum due to these calibration errors.

The WMAP RF plumbing is very complexwith 10 horns per side, 20 DA’s, 40 amplifier chains.

Huge Amount of Data• 5 bands.• 23, 33, 41, 61 & 94 GHz.• 2, 2, 4, 4 & 8 temperature differences per

band. Two detectors for each differential T.• 128, 128, 102.4, 76.8 & 51.2 ms/sample.• 279 temperature differences per second.• 53 billion samples in 3 years.• About 2108 samples per low l polarization.• Systematic error control is critical!

Systematic Error Control

MAP’s Orbit

Temperature Stability• 7% p-p yearly

insolation modulation from eccentricity of Earth’s orbit

• Slow change in thermal properties: 3%/yr in albedo or emissivity.

Pioneer anomaly could be explained by 3% emissivity anisotropy.

Scan Strategy• 6 Months for full sky

coverage1 hour precession 2 minute spin

Not to scale:Earth — L2 distance is 1% of Sun — Earth Distance

Noise Pattern is not Uniform

• Stokes I, Q, U & <QU> all have different noise patterns.

Combination to remove foreground

QVW as RGB

Scattering creates Polarization

Reionization puts scatterers at A: many degree scale

Scatterers during recombination are at B: degree scale

Top view of same S-T Diagram• Electrons at A or

B see a somewhat different piece of the surface of last scattering than we do.

• If electrons at A or B see a quadrupole anisotropy then we get polarization.

ROM Foreground Fit in P06 Cut

• m = -0.6• EE

– Bs = 0.36, s = -3.0

– Bd = 1.0, d = 1.5

• BB:– Bs = 0.30, s = -2.8

– Bd = 0.50, d = 1.5

Final Results

EE only: = 0.10 0.03

TT, TE & EE: = 0.09 0.03

Foreground vs CMB Polarization

Foreground vs CMB T

Comparison to Previous Best Fit

• Now we have = 0.09 0.03 instead of = 0.117 0.055 for the WMAP I best fit.

• But quite a bit less than the old WMAP I TE only = 0.17 0.04

Effects on Peak Position: lpk

+ Open or vacuum dominated Universes give larger distance to last scattering surface

+ High matter density gives smaller wavelength

CMB alone does not imply flatness

• But CMB + Ho (or other data) do imply flatness and a dark energy dominated Universe.

CDM is a Good Fit

But so is “super Sandage”

Non-flat Dark Energy Fitting!

k = 0, w = -1 is OK: -0.93 > w > -1.14

With many datasets combined, the equation of state w and the curvature can be measured together.

Late ISW Effect: Another test for

Potential only changes if m 1 (or in non-linear collapse, but that’s another story [Rees-Sciama effect]).

Potential decays at z 0.6

CMB-LSS correlation seen by WMAP

• This late ISW effect occurs on our past light cone so the T we see is due to structures we also see.

• Correlation between WMAP and LSS seen by:– Boughn & Crittenden (astro-ph/0305001) at 2.75 with hard X-ray

background and 2.25 with NVSS– Nolta et al. (astro-ph/0305097) at 2 with NVSS– Afshordi et al (astro-ph/0308260) at 2.5 with 2MASS

2MASS galaxies reach z = 0.1

Credit: Tom Jarrett, IPAC

WIDE-FIELD INFRARED SURVEY EXPLORER

I am the PI on a MIDEX called WISE, an all-sky survey in 4 bands from 3.3 to 23 m. WISE will find and study the closest stars to the Sun, the most luminous galaxies in the Universe, and also map the large-scale structure out to redshift z=1, covering the era when the late ISW effect should be generated.

WISE might fly in 2009, but is being delayed by NASA’s budget woes.

CONCLUSIONS• The intrinsic anisotropy of the CMB, first

observed by the COsmic Background Explorer (COBE), has now become an extremely significant tool for the study of the Universe in the hands of the Wilkinson Microwave Anisotropy Probe - another Explorer mission.

• WMAP will continue for a few more years. • ESA’s Planck mission will continue to exploit

the CMB with higher angular resolution, higher sensitivity and higher frequency data.