Transcript Cosmology: Answers and Questions David Spergel Princeton University We now have a standard cosmological model  General Relativity + Uniform Universe    Big Bang Density of universe determines its.

Cosmology: Answers
and Questions
David Spergel
Princeton University
We now have a standard
cosmological model

General Relativity + Uniform Universe



Big Bang
Density of universe determines its fate + shape
Universe is flat (total density = critical density)
 Atoms 4%
 Dark Matter 23%
 Dark Energy (cosmological constant?) 72%
Universe has tiny ripples



Adiabatic, scale invariant, Gaussian Fluctuations
Harrison-Zeldovich-Peebles
Inflationary models
Quick History of the Universe


Universe starts out hot,
dense and filled with
radiation
As the universe expands,
it cools.
• During the first minutes, light
elements form
• After 500,000 years, atoms form
• After 100,000,000 years, stars start
to form
• After 1 Billion years, galaxies and
quasars
Thermal History of Universe
radiation
matter
NEUTRAL
r
IONIZED
103
104
z
Growth of Fluctuations
•Linear theory
•Basic elements have
been understood for
30 years (Peebles,
Sunyaev &
Zeldovich)
•Numerical codes
agree at better than
0.1% (Seljak et al.
2003)
Sunyaev & Zeldovich
CMB Overview


We can detect both CMB
temperature and
polarization fluctuations
Polarization Fluctuations
can be decomposed into
E and B modes
q ~180/l
ADIABATIC DENSITY FLUCTUATIONS
ISOCURVATURE ENTROPY FLUCTUATIONS
Determining Basic
Parameters
Baryon Density
Wbh2 = 0.015,0.017..0.031
also measured through D/H
Determining Basic
Parameters
Matter Density
Wmh2 = 0.16,..,0.33
Determining Basic
Parameters
Angular Diameter
Distance
w = -1.8,..,-0.2
When combined with
measurement of matter
density constrains data to a
line in Wm-w space
Predictive Theory Motivates
Precision Measurements

COBE measurement of spectrum (1990) and
detection of large scale fluctuations (1992)
 Detection of first acoustic peak (TOCO [Miller et
al. 1999])
 Rapidly improving ground and balloon-based
measurements (1999-2002)



First peaks (TOCO, BOOM, DASI, …)
EE (DASI)
Wilkinson Microwave Anisotropy Probe (2003)

TT & TE
Wilkinson Microwave Anisotropy Probe
A partnership between
NASA/GSFC and Princeton
Science Team:
NASA/GSFC
Chuck Bennett (PI)
Michael Greason
Bob Hill
Gary Hinshaw
Al Kogut
Michele Limon
Nils Odegard
Janet Weiland
Ed Wollack
Brown
UCLA
Greg Tucker
Ned Wright
UBC
Mark Halpern
Chicago
Stephan Meyer
Princeton
Chris Barnes
Norm Jarosik
Eiichiro Komatsu
Michael Nolta
Lyman Page
Hiranya Peiris
David Spergel
Licia Verde
WMAP Spacecraft
upper omni antenna
line of sight
back to back
Gregorian optics,
1.4 x 1.6 m primaries
passive thermal radiator
60K
focal plane assembly
feed horns
secondary
reflectors
90K
thermally isolated
instrument cylinder
300K
warm spacecraft with:
- instrument electronics
- attitude control/propulsion
- command/data handling
- battery and power control
MAP990422
medium gain antennae
deployed solar array w/ web shielding
WMAP Design Goal:
Minimize Systematics
•Differential design
•milliK thermal Stability
•Multiply linked scan
pattern
A-B-A-B B-A-B-A
•Many cross-checks
possible within data set
One of 20
June 30, 2001
K - 22GHz
Ka - 33GHz
Q - 41GHz
V - 61GHz
W94GHz
W94GHz
5º
Q band
V band
W band
Foregrounds

Synchrotron


Dust


Finkbeiner Davis Schlegel
template good fit
Free-Free


Drops off sharply with n
H a surveys (WHAM,
VTSS, SHASSA)
Point sources

Measured through skewness

Multifrequency power spectrum

Extrapolate source counts
FOREGROUND CORRECTED
MAP
Angular Power Spectrum is Robust

Same results for 28
different channel
combinations
 Same results for auto
and cross-correlations
 Same results for
different weightings,
analysis schemes
Temperature
85% of sky
cosmic variance
Best fit model
1 deg
Temperaturepolarization
Simple Model Fits CMB data
Readhead et al. astro/ph 0402359
CMB & BBN



CMB measures
baryon/photon ratio
Determines D/H ratio
Helium



Was discrepant with CMB
and D/H
New neutron lifetime
measurement removes
problem
Lithium


Sensitive to chemical
evolution of Deuterium
Early destruction
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
Model Predicts Universe
Today
SDSS Tegmark et al.
Astro-ph/0310723
Verde et al. (2003)
Evolution from Initial
Conditions I
WMAP team
assembled
WMAP completes
2 year of
observations!
DA leave
Princeton
WMAP at Cape
Evolving Initial Conditions II
Verde
et al.
Evolution from Initial
Conditions III
Verde
et al.
Consistent Parameters
WMAP+CBI+ All
ACBAR
CMB(Bond)
CMB+
2dFGRS
CMB+SDSS
(Tegmark)
Wb h 2
.023 + .001
.0230 + .0011
.023 + .001
.0232 + .0010
Wxh2
.117 + .011
.117 + .010
.121 + .009
.122 + .009
h
.73 + .05
.72 + .05
.73 + .03
.70 + .03
ns
.97 + .03
.967 + .029
.97 + .03
.977 + .03
s8
.83 + .08
.85 + .06
.84 + .06
.92 + .08
Consistency!
s8
CMB + Lensing
Contaldi et al. (2003)
W







Spergel et al. 2003
Hubble Constant
Baryon Abundance
Lensing Amplitude
Supernova Distance
Scale
Cluster Abundances
Stellar Ages
Helium Abundance
New Questions
 Physics
that we don’t know (String theory,
quantum cosmology,…
 How did the universe begin?
 What is the dark energy?
 Physics
that we don’t know how to
calculate (Non-linear hydro, star formation…


First stars
Galaxy formation
Probing the Dark Energy
Detected only through Friedman equation:
?
How Can We Measure a(t)?
 Standard
Ruler (angular diameter
distance)
CMB peak positions
Matter power spectrum
 Standard

Supernova
 Growth

Candle
Rate of Structure
Gravitational Lensing
Baryon Oscillations
CMB
C(q)
Baryon oscillation scale
q
1o
Galaxy
Survey
Limber Equation
Selection
function
(weaker effect)
C(q)
q
photo-z slices
Baryon Oscillations as a
Standard Ruler

In a redshift survey, we
can measure correlations
along and across the line
of sight.
 Yields
H(z) and DA(z)!
[Alcock-Paczynski Effect]
dr = DAdq
dr = (c/H)dz
Observer
SDSS and Baryon Wiggles

Purely geometric test
(SDSS + WMAP)
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
Eisenstein et
al. (2005)
What is the dark energy?
-1.0
-1.0
CMB data consistent with other
data sets if w is near -1
(dark energy is a cosmological
constant)
-1.0
-1.0
Current Constraints
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
Seljak et al.
2004
ACT:The Next
Step




Atacama Cosmology
Telescope
Funded by NSF
Will measure CMB
fluctuations on small
angular scales
Probe the primordial
power spectrum and the
growth of structure
ACT COLLABORATIONS
Government Labs
PENN
CatÓlica
Haverford
Schools
Museums
Princeton
Toronto
CUNY
…united through research, education and public outreach.
Simulations of mm-wave data.
 1%
1.4
Survey area
0
 2%
High quality area
150 GHz
SZ Simulation
MAP
MBAC on ACT
1.7’ beam
2X noise
PLANCK
PLANCK
Where will we
be with CMB
Bond et al.
astro-ph/046195
Cosmic Timeline for ACT Science
• First galaxies
• Universe is reionized
• Ostriker-Vishniac/KSZ
• Extraction of
cosmological
parameters
• Initial conditions for
structure formation
z = 1000
t = 4 x 104 yrs
Primary CMB
• Surveys of Sunyaev-Zel’dovich (SZ) clusters
• Diffuse thermal SZ
• N(mass,z) – Evolution of Cosmic Structure
• Lensing of the CMB
• The growth of structure is sensitive to w and mn
• Additional cross-checks from correlations among effects
z=7
t = 3 x 106 yrs
CMB Lensing
z=1
t = 1 x 109 yrs
OV/KSZ
Diffuse Thermal SZ
z = .25
t = 12 x 109 yrs
now
Cluster Surveys
Sunyaev-Zel’dovich (SZ) clusters
Telectron = 108 K
Coma Cluster
e-
ee-
eee-
ee-
e-
Optical:
mm-Wave: SZ –
X-ray Flux:
Redshift and Mass
Compton Scattering
Mass
SZ Signature
Hot electron gas
imposes a unique
spectral signature
145 GHz
decrement
220 GHz
null
270 GHz
increment
NO SZ Contribution in Central Band
1.4°x 1.4°
Coordinated Cluster
Measurements
Galaxy Cluster
Identify and measure
>500 clusters in an
unbiased survey with
multi-wavelength
observations
HOT Electrons
limits of 3 x 1014 estimated from simulations
• Science derived from N(mass,z)
• Mass
Lensing of the CMB
• Lensing arises from integrated
mass fluctuations along the line
of sight.
-1850
(K)
• The CMB acts as a fixed
distance source, removing the
degeneracy inherent to other
lensing measurements.
0
• Signal at l = 1000-3000
• Image distortion – only a
minor effect in the power
spectrum.
• Must have a deep, high
fidelity map to detect this
effect.
1820
CMB
1.4°x 1.4°
Lensing of the CMB
-34
(K)
• RMS signal well above
noise floor.
• Isolate from SZ and point
sources spectrally.
0
• Identify with distinctive
4-point function.
34
Lensing Signal
1.4°x 1.4°
2% of CMB RMS
Cross-Correlating Lensing
and CMB



CMB provides a source plane at z = 1100 with
very well determined statistical properties (but
poorer statistics)
CMB + Quasar & Galaxy Counts will measure
bias
CMB lensing+ Galaxy lensing crosscorrelation improves parameter
measurements by roughly a factor of 3
(Mustapha Ishak)
CMB +
SN
Add Lensing
CMB +
Lensing
X-correlate
ACT \REGION: Target for
future lensing surveys
ACT will begin surveying in 2006
We already plan deep multi-band
imaging with SALT of low extinction
part of ACT strip (200 square degrees)
Would be a very interesting target for
a lensing survey
Cosmology Now Has A Standard Model

Basic parameters are accurately determined


Many can be measured using multiple techniques
CMB best fit now consistent with other
measurements

Mysteries remain: dark matter, dark energy,
physics of inflation
 Next step:
Probe Physics Beyond the Standard Model
THANK YOU !

CMB
Polarization
Weak signal


signal is statistical rather than a
detection in each pixel
Foregrounds


Synchrotron (dominant)
Dust

Systematic Uncertainties
 Significant uncertainty in
reionization redshift



Will improve with more data
Polarization auto-correlation
Dt/t~0.1 in 4 year data
Polarization Measurements

New window into Early Universe




Gravity waves from inflation
Reionization
Constraints on isocurvature admixtures, ionization history, etc.
CMB Polarization Measurements





Upcoming WMAP release
BOOMERANG Polarization flight
Lots of exciting ground and balloon experiments under development
Planck
CMBPOL
CMB Polarization: Another
Dark Energy Probe

When combined with optical measurements, this will
enable us to cleanly measure the growth rate of
structure: an independent probe of the properties of the
dark energy
 Polarization lensing/ISW cross-correlation will enable us
to probe the properties of dark energy at z~5-50 -- an
epoch inaccessible to other experiments
 Small scale polarization experiments point the way
towards the detection of gravity waves
W94GHz
Is the Universe Finite or
Infinite?
Topology
Two Torus
Other Tilings
Three Torus
Same idea works in three space dimensions
Infinite number of tiling
patterns
This one only works in hyperbolic space
Spherical Topologies
This example only works in
spherical space
Dodecahedral Space
Tiling of the
three-sphere by
120 regular
dodecahedrons
Homogeneous & Isotropic
Universe
The microwave background in a
multi-connected universe
Matched circles in a three torus
universe
If the universe was finite:
Cornish, Spergel, Starkman, Komatsu
What we see in the WMAP data:
UNIVERSE IS BIG!
Conclusions
 Cosmology
is in a golden age!
 Advances in technology are enabling us to
probe the physics of the very early
universe and the birth of structure
 So far, the standard model appears to fit
the data, but stay tuned!
Pen, Seljak, Turok astro-ph/974231
ACTIVE ISOCURVATURE MODELS
Key Historical Papers
Acoustic Peaks


Sunyaev & Zeldovich, ApSS, 7, 3 (1970)
Peebles & Yu, ApJ 162, 815 (1970)
CDM

Peebles ApJ 263, L1 (1982) proposed cold dark matter
Lambda




Gunn & Tinsley (1975)
Turner, Steigman & Krauss (1984)
Peebles ApJ 284, 439 (1984)
Supernova papers
Key Technological Step:
Revolutionary CMB
Cameras (multiplexed, filled arrays of
thousands of bolometers)
•Planning three 1024-element
arrays for fine-scale CMB on
ACT: the MBAC.
•Propose 4000-element
polarized camera for ACT to
round-out science return via
lensing and inflationary
probe.
SHARC II 12x32 Popup Array
32 mm
Completed “close-packed” 12x32 bolometer array
Torsional yoke attachment
1
mm
Linear array after folding
One element
of array
Too Many Bumps and
Wiggles?


C2 = 1.08 (3% probability)
Need to include several systematic effects in error budget



Lensing of CMB
Beam variations & asymmetries
1/f noise non-Gaussian contribution to 4pt
More to
Come….
Quic kTime™ and a TIFF ( Uncompr es s ed) dec ompres sor ar e needed to s ee this pic ture.

WMAP has effectively no lifetime
limit
 Approved for 4 years of operation
 Improved TE + EE data will
significantly improve t
measurement
 More accurate 2nd and 3rd peaks
Calibrate ground-based high l
measurements
 Improvements in complementary
measurements (SDSS,
supernova[ACS, Carnegie,
NOAO])
0.30

0.20
t 0.10
0,00
0.90
0.95 1.00
ns
1.05 1.10
Ground Based High
Resolution Surveys
 Sunyaev-Zeldovich
detections of clusters
and hot intercluster gas
 Ostriker-Vishniac fluctuations from z~5-20
from motions of reionized gas
 Gravitational Lensing of CMB


Correlates with optical surveys, quasars
Probes mass fluctuations along line of sight
Too Little Large Scale Power?

Lack of large scale power




Seen in COBE but clearer
now
Is the universe finite?
Are we seeing a
characteristic scale?
Is it just chance?
LCDM Best Fit Parameters
Wilkinson Microwave Anisotropy Probe
A partnership between
NASA/GSFC and Princeton
Science Team:
NASA/GSFC
Chuck Bennett (PI)
Michael Greason
Bob Hill
Gary Hinshaw
Al Kogut
Michele Limon
Nils Odegard
Janet Weiland
Ed Wollack
Brown
UCLA
Greg Tucker
Ned Wright
UBC
Mark Halpern
Chicago
Stephan Meyer
Princeton
Chris Barnes
Norm Jarosik
Eiichiro Komatsu
Michael Nolta
Lyman Page
Hiranya Peiris
David Spergel
Licia Verde
WMAP Spacecraft
upper omni antenna
line of sight
back to back
Gregorian optics,
1.4 x 1.6 m primaries
passive thermal radiator
60K
focal plane assembly
feed horns
secondary
reflectors
90K
thermally isolated
instrument cylinder
300K
warm spacecraft with:
- instrument electronics
- attitude control/propulsion
- command/data handling
- battery and power control
MAP990422
medium gain antennae
deployed solar array w/ web shielding
WMAP Design Goal:
Minimize Systematics
•Differential design
•milliK thermal Stability
•Multiply linked scan
pattern
A-B-A-B B-A-B-A
•Many cross-checks
possible within data set
One of 20
June 30, 2001
K - 22GHz
Ka - 33GHz