Transcript Latest Results from WMAP: Three

Latest Results from WMAP:
Three-year Observations
Eiichiro Komatsu
University of Texas at Austin
January 24, 2007
WMAP Three Year Science Team
NASA/GSFC
Chuck Bennett [PI] (-> JHU)
Mike Greason
Bob Hill
Gary Hinshaw [CoI]
Al Kogut
Michele Limon
Nils Odegard
Janet Weiland
Ed Wollack
Princeton
Chris 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)
Chicago
Steve Meyer [CoI]
UCLA
Ned Wright [CoI]
Brown
Greg Tucker
UBC
Mark Halpern
Night Sky in Optical (~0.5nm)
Night Sky in Microwave (~1mm)
A. Penzias & R. Wilson, 1965
R. Dicke and J. Peebles, 1965
3.5K
NOW
P. Roll and D. Wilkinson, 1966
D.Wilkinson
“The Father of
CMB
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 WMAP
COBE
1989
COBE
Press Release from
the Nobel Foundation
[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.
WMAP
2001
WMAP
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
Dark Energy/
New Physics?
Baryonto-Photon
Ratio
Matter-Radiation
Equality Epoch
R. Sachs and A. Wolfe, 1967
•SOLVE GENERAL RELATIVISTIC BOLTZMANN
EQUATIONS TO THE FIRST ORDER IN PERTURBATIONS
Boltzmann Equation
• Temperature anisotropy, Q, 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:

ds  a 1 h00 d   ij  hij dx dx
2
2
2
Newtonian potential
i
j

Curvature perturbations
the Sachs-Wolfe terms are given by
where g is the directional cosine of photon propagations.
1. The 1st term = gravitational redshift
h00/2
2. The 2nd term = integrated Sachs-Wolfe effect
(higher T)
Dhij/2
CMB to Cosmology
Low Multipoles (ISW)
&Third
Baryon/Photon Density Ratio
Constraints on Inflation Models
ns: Tilting Spectrum
ns>1: “Blue
Spectrum”
ns: Tilting Spectrum
ns<1: “Red Spectrum”
News from 3-yr data is…
POLARIZATION MAP!
Composition of Our Universe
Determined by WMAP 3yr
Dark
Energy
Mysterious “Dark Energy”
occupies 75.93.4% of the
total energy of the Universe.
76%
4%
Baryons
20%
Dark
Matter
Parameter Determination (ML):
First Year vs Three Years
(w/SZ)
(w/o SZ)
2.22
0.127
73.2
0.091
0.954
0.236
0.756
• 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
Parameter Determination (Mean):
First Year vs Three Years
(w/SZ)
2.229
0.128
73.2
0.089
0.958
0.241
0.761
• ML and Mean agree better for the 3yr data.
– Degeneracy broken!
(w/o SZ)
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 Bmode 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 GW
The 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
Summary
•Tau=0.09+-0.03
•
– 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.
What Should WMAP Say About
Neutrinos?
3.04)