Transcript Hangzhou Lecture #3 - University of California, Los Angeles

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:
25 April 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.”
Animated View of Inflation
• Quantum
fluctuations occur
uniformly
throughout spacetime
• Future light cones
have radii of
(c/H)[exp(Ht)-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  = 3c2T/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
complex
with 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 2108 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 coverage
1 hour precession
Not to scale:
Earth — L2 distance is
1% of Sun — Earth Distance
2 minute spin
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!
With many
datasets
combined,
the equation
of state w
and the
curvature can
be measured
together.
• k = 0, w = -1 is OK: -0.93 > w > -1.14
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 largescale 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.