Transcript No Slide Title

An Experimentalist’s
Perspective on Testing Field
Theories with the CMB.
L. Page, AlbaNova, June 2007
The current cosmological
model agrees with virtually all
cosmological measurements
regardless of redshift or
method.
The model assumes a flat geometry (a couple %), a
new form of matter (>15), something that mimics
a cosmological constant (many ), and a deviation
=1, ~3).
from scale invariance (
WMAP3 only
WMAP3 + all
Models based on some kind of field theory
of the early universe predict ns.
closed
“Geometric
Degeneracy”
CMB alone tells
us we are on the
“geometric
degeneracy” line
open
WMAP3 only best fit LCDM
  1  b  c  
Assume
flatness
Reduced
Testing Specific Field Theories
Experimental handles
(1) Spectrum of Fluctuations
&
(2) Anisotropies from Gravitational Waves.
(3) Non-Gaussanity
Types of Cosmological
Perturbations
Temperature
Scalars:
,
E polarization
Temperature
Tensors: h (GW strain)
E polarization
B polarization
0.3
Or less!
n and r are predicted by models of the early universe
Physical size = plasma speed X
age of universe at decoupling
Angular Power
Spectrum. Power spectrum
~10
early in inflation
~0.40
later in inflation
The overall tilt of
this spectrum--encoded in the
“scalar spectral
index” ns--- is the
new handle on the
early universe.
Spectral Index, Experimental Challenges
Three different
spectra that
differ only in
spectral index.
The black line is
the best WMAP
model.
Spectral Index
Normalize the spectra
to l=220 (mimics nsamplitude degeneracy)
The two window
functions are for 0.1 deg
FWHM beams with a
1% difference in solid
angle. Only WMAP has
achieved anything like
this accuracy.
Spectral Index
Divide by fractional
window function.
Conclusion: To
probe the index the
beams need to be
understood to the
1% level.
In addition, there
are astrophysical
challenges.
Spectral Index: Astrophysical Challenges
The formation of the first stars produces free
electrons that:
(1) rescatter CMB photons thereby reducing the
anisotropy and
(2) polarize the CMB at large angular scales.
These effects mimic a change in ns:
“the ns - tau” degeneracy
WMAP measures (2) to break the degeneracy
TT
TE
EE
BB
r=0.3
Approx EE/BB
foreground
BB inflation
BB Lensing (not primordial)
Low-l EE/BB
EE
EE Polarization: from
reionization by the
first stars
Just Q and V bands.
BB
BB Polarization: null
check and limit on
gravitational waves.
r<2.2 (95% CL) from just EE/BB
Degeneracy
1yr WMAP
No SZ marg
WMAP1+
ACBAR+
CBI
L
3yr WMAP
Knowledge of optical depth breaks the
degeneracy
Index and Tensors
ns=0.95
(
in 2d)
(
in 2d )
ns=1
What Does the Model Need to
Describe the Data?
changing one of the 6 parameters at a time….
Model needs
Model needs
,
8
not unity,
Model needs dark matter,
{
(“2.8 sigma”)
6
248
….but Eriksen &
Huffenberger
(“15 sigma”)
Model does not need: “running,” r, or
massive neutrinos,
< 3.
The data are, of course, less restrictive when there are more parameters.
Gravitational Waves
TT
Approx EE/BB
foreground
TE
EE
B modes from
tensors only.
G-waves decay
once inside the
horizon.
BB r=0.3
B modes from lensing
of E modes (not
primordial).
Reionization peak
(zr=10)
Horizon size at
decoupling (zdec=1089)
Expectations at l=100
Dust at 150 GHz
from FDS
Lensing BB
1000 close packed
dets for 1 year at
350 uK-sec^{1/2}
raw or 700 uKsec^{1/2} on sky.
Boxes inst
sensitivity not sky
rms sens.
Lensing B modes
From Jo Dunkley
Non-Gaussanity
The quadrapole is not anomalously low. For the
full sky, the 2-pt correlation function is not
anomalous.
All “detections” of non-Gaussanity are based on a
posteriori statistics. That is, one seeks any oddity
in the maps and quantifies it.
The North-South asymmetry was visible in the
COBE data.
It would be fantastic to find a clear signature of cosmic nonGaussanity. The WMAP team has not found one.
A significant fraction of the full-sky quadrupole
comes from:
Alignment? See Max!
(de Oliveira-Costs et al. 2004)
(Hajian 2007)
Detection of SH
persists!
Note “fingers” present in the
southern Galactic hemisphere.
Extra cold spot:
(Vielva et al. 2004, Cruz et
al. gave 1.8% prob. 2005)
Distribution by map temp. by frequency (accounting for uneven weighting)
Gaussian
Data are an excellent representation of a Gaussian!
40 pix
Cold spot
10 pix
Distribution by resolution.
0.250 pix
What’s Next?
ACT
SZA
(Interferometer)
Owens Valley
2006
PAPPA
BRAIN
SCUBA2
(12000 bolometers) QUIET
CLOVER
EBEX
SPIDER
2008
2009
(3000 bolometers)
Chile
QUAD
BiCEP
2007
SPT
(1000 bolometers)
South Pole
APEX
(~400 bolometers)
Chile
Polarbear-I
(300 bolometers)
California
Planck
(50 bolometers)
L2, data 2012
Science:
Growth of structure
Eqn. of state
Neutrino mass
Ionization history
ACT
Observations:
CMB: l>1000
Cluster (SZ, KSZ
Atacama Cosmology Telescope
X-rays, & optical)
Diffuse SZ
OV/KSZ
Lensing
Inflation
Power spectrum
X-ray
Optical
Collaboration:
Cardiff
Rutgers
Theory
Columbia CUNY Haverford INAOE NASA/GSFC
NIST
Princeton
UBC U. Catolica U. KwaZulu-Natal UMass UPenn U. Pittsburgh U. Toronto
New Type of Telescope
M. Devlin is lead
Telescope at
AMEC in
Vancouver. Ship
to Chile in
2006.
Arrays of bolometers
(S. Staggs is lead)
Moseley et al, NASA/GSFC
Irwin et al.
Warm electronics
based on SCUBA2
Halpern et al. UBC
8x32 Array of 1mm x 1mm
detectors. Now in Chile on
the telescope.
First Light from ACT
June 8, 2007
Expanding CMB Photosphere
(with Temperature decrease
scaled out)
Stuart Lange, Senior Thesis, 2007
An Experiment for the Century
Power spectrum of
difference between
two maps made
100 years apart.
Error bars with a
3000x3000 array
of detectors.
Thank You!
From Wayne Hu
CMB Polarization
Polarization of the CMB is
produced by Thompson
scattering of a quadrupolar
radiation pattern.
E
2 deg
Whenever there are free electrons,
the CMB is polarized.
The polarization field is decomposed
into “E” and “B” modes.
B
Seljak & Zaldarriaga
Terminology:
E/B Modes
k
k
Density wave
E-modes
Gravitational
wave
B-modes
Equation of State & Curvature
Interpret
as amazing
consistency
between
data sets.
WMAP+CMB+2dFGRS+SDSS+SN
(3) The spectrum of scalar fluctuations.
WMAP
z=1089
2D
2dFGRS
z<3
3D
Lyman
alpha
Verde et al. 2003
and now
SDSS as
well.
Low-l EE/BB
EE (solid)
BB (dash)
EE/BB model at 60 GHz
r=0.3
Since reionization is late we see it at large angular scales. This is
our handle on the optical depth.
More simulations of mm-wave sky.
 1%
1.4
Survey area
0
 2%
High quality area
150 GHz
SZ Simulation
MBAC on ACT
1.5’ beam
PLANCK
Burwell/Seljak
WMAP
PLANCK
/ Diffuse KSZ
Target
Sensitivity
(i.e. ideal stat
noise only)
SPT &
APEX as
well.
ACT
/ Diffuse KSZ
de Oliveira-Costa
(2) Gaussanity
Express sky as: T( ,  ) 
a
Y ( , )
lm lm
l ,m
Gaussanity means that the real and imaginary parts of
each alm are independent normal deviates.
We quantify the Gaussanity with:
Komatsu et al. ‘03
Current WMAP limit:
Planck limit : fNL=5
Ultimate CMB limit : fNL=3
Simple models of inflation have fNL=0.05
More exotic models of inflation have fNL=10 to 100.
Babich &
Zaldarriaga 04
The scalar index, ns, with six
parameters.
WMAP
+SDSS Tegmark et al. 2004
+SDSS Galaxies and Lya
Seljak et al. 2004
Simple models of inflation predict:
This is significant in that it is a clear
departure from scale invariance.
We expect ns to 1% by 2008 from the CMB.
Running of the scalar index.
SDSS Galaxies
Tegmark et al. 2004
In the two recent analyses of WMAP
plus SDSS there is no evidence for
running.
An analysis of CBI+WMAP+LSS
shows evidence of running at the 3sigma level (-0.085+/-0.031) but the
CBI team does not place a lot of
weight on the result.
Galaxies and Lya
Seljak et al. 2004
Readhead et al. 2004
Stability of instrument is critical
Physical temperature of
B-side primary over three
years.
Model based
on yr1 alone
Three parameter fit to
gain over three years
leads to a clean
separation of gain and
offset drifts.
3yr Model
Data based
on dipole
Jarosik et al.