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The CMB and Gravity Waves. John Ruhl Case Western Reserve University. 3/17/2006, CERCA at St. Thomas. WMAP 3yr temperature maps… what the sky really looks like. 23 GHz. 61 GHz. 33 GHz. 94 GHz. 41 GHz. (What the sky really looks like). WMAP 3-year map, “galaxy subtracted”. - PowerPoint PPT Presentation
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The CMB and Gravity Waves
John Ruhl
Case Western Reserve University
3/17/2006, CERCA at St. Thomas
WMAP 3yr temperature maps… what the sky really looks like.
(What the sky really looks like)
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23 GHz
33 GHz
41 GHz
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61 GHz
94 GHz
WMAP 3-year map, “galaxy subtracted”
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Boomerang “T” maps
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B03:
150GHz (published)
10’ resolution,
~1000 sq. deg.
Acbar maps
150GHz,
5’ resolution,
10’s of sq. deg,
More coming soon.
<TT> Power spectra=> CDM looks good
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Pow
er S
pect
rum
(u
K2)
Legendre l
B03 <TT> power spectrum => CDM still looks good
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WMAP(3yr)+others <TT>
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Figure 18, Hinshaw etal, WMAP 3-year release
WMAP 3yr data… theory-scaled to high-ell…
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Fig 5, Spergel etal, WMAP 3-year release
“Post B03”(pre-WMAP3) parameters
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MacTavish etal, B03 release
Still of interest
r = T/S: primordial gravity waves (tensor modes)
nT: spectral index of tensor mode power spectrum
ns: spectral index of density perturbation power spectrum,
Dark Energy w, w’, etc
non-gaussianity
Isocurvature modes
Suprises: eg “not flat”, obs. disagreements, etc.
ns vs r : current limits
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Plot from M. Tegmark, TFCR report
r
T
/S
ns
CMB“goal”
WMAP 3yr, r<0.28 (95%CL) w/SDSS
CMB polarization
Two causes:
1. “Normal” CDM: Density perturbations at z=1000 lead to velocities that create local quadrupoles seen by scattering electrons.
=> “E-mode polarization” (no curl)
2. Gravity waves: create local quadrupoles seen by scattering electrons,
=> “B-mode polarization” (curl)
Both are caused by the polarization dependence in Thomson scattering
Anisotropic illumination => polarization
Green = probability of emitting in that direction…Observer
Vertical pol.
No emission to observer
Horizontal pol.(in and out of page)
Line of sight
Line of sight
Line of sight
Gravity
Wave
Surfa
ce o
f last
scat
terin
g
Gravity waves at z=1000
… create local quadrupoles around an electron at z=1000.
Flavors of CMB polarization
Two patterns:
Density perturbations: curl-free, “E-mode”
Gravity waves: curl, “B-mode”
IAU convention for Q and U
North
East
+
-
Q
North
East
U
+
-
Each point on the sphere has a Q or U value determined by the polarization at that point.
Linear polarization Stokes parameters
Stokes Parameters vs. E and B mode The E-mode (or B-mode) value at a point on the sphere depends on the polarization pattern all around it.
Direction you’re looking on the sky (2 components)Same thing, but variable for integration
Polar coordinates of relative to
Weighting function (Note: w=0 for theta =0)
E and B mode patternsBlue = + Red = -
“local” Q “local” U
For a given circle ( ), circumference goes as , while , so the contribution of that circle goes as 1/ .
E and B mode patterns
Unchanged under parity flip
Sign reverses under parity flip
E-mode
B-mode
Seljak and Zaldarriaga, astro-ph/9805010
E-mode polarization (simulation)
Seljak and Zaldarriaga, astro-ph/9805010
Color: |E|
Bars: E-mode polarization direction and size
B-mode polarization (simulation) Seljak and Zaldarriaga, astro-ph/9805010
Color: |B|
Bars: B-mode polarization direction and size
CMB Polarization power spectra
Primordial B-modes
Reionization bump
Shape and amplitude of EE are predicted by CDM.
``Shape” of BB is predicted “scale-invariand GW’s”.
Amplitude of BB is model dependent.
The State of CMB polarization measurements
WMAP <TE>, Kogut etal
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Fig 22, Hinshaw etal, WMAP 3yr release
EE power spectrum data
EE power spectrum data
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Figure 22, Page etal, WMAP 3-yr release.
B03 and WMAP 3yr
High-l BB power spectrum data
WMAP Polarization data
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BB limit (1sigma)
r=0.3 BB
Foreground model
Figure 25, Page etal, WMAP 3yr release
Current “high-l” BB limits
The Future of CMB polarization measurements
Foregrounds
Technology
Foregrounds at l=50
S. Golwala, 2005
r = 0.01
DustSynchrotron
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Galactic Foregrounds: l-space
From G. Hinshaw, TFCR report
“Future, large angular scale” CMB Polarization Experiments
deployed funded proposed
Quad: NTD bolo, 90/150 GHz, ~0.2deg, ~100 elements. Spole.
Bicep: NTD bolo, 90/150 GHz, ~1deg, ~100 elements, Spole
Ebex: SC Bolos, 90-400GHz, ~0.2deg, ~1000 elements, balloon
Pappa: SC bolos, 90/150GHz, ~1deg, ~20 elements, balloon
Clover: SC bolos?, 90-220GHz?, ~1deg, ~1000 elements, Chile
Quiet: Hemts, ??? freqs/elements, Chile
Polarbear: SC bolos, 90/150/220GHz, ~0.2deg, ~? Elements, Chile
Spider: SC bolos, 40-220GHz, ~1deg, ~1000 elements, balloon
CMBPOL: ???, satellite [see TFCR (aka “Weiss”) report]
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Sensitivities
1 10 100 1000 1 10 100 1000
Plot from T. Montroy
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Predicted Future Experiment Sensitivities
From G. Hinshaw, TFCR report
Systematics to conquer
Table 6.1 from TFCR report
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Experiment strengths and weaknesses
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Experiment strengths and weaknesses
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On-chip modulator(continuous)
Detector feed(s) Other optics
“on chip”
modulator photons
“After primary” modulator(continuous)
Detector modulatorfeed(s) Other optics
“on chip”
photons
“Ideal” Future experiment to probe Inflation
• Lots of sensitive detectors and integration time
• “Good enough” angular resolution (to measure l=100 bump)
• “Large enough” sky coverage (to measure reionization bump)
• Low systematics, polarization modulator… optimized for Polarization.
Ultimate instrument: CMBPOL satellite
Realistic (proposed) instrument…
Spider(CMBPOL on a rope)
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Canada: U. Toronto, U.BC
UK: Cardiff, Imperial Coll. London
USA: Caltech, Case, JPL, NIST
A balloone-borne“low l” machine
Six frequency bands
Six telescopes
Clean refractor optics
Halfwave plates
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CIT/JPL Polarized Array8x8=64 pixel phased-array “patches”,
2 polarizations on each.
JPL Antenna-coupled bolometer,and crossed dipole elements
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Around the world flight from Australia, night time observing only
Large sky coverage => get to low l
Spider baseline bands and sensitivities
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1856 detectors
6 bands
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Sensitivities
Plot from T. Montroy
Benefit of measuring the Reionization bump
Plot from C.L. Kuo
(1 year)
WMAP 3-year EE: tau = 0.10 +- 0.03WMAP 3-year all: tau = 0.09 +- 0.03
Summary
1. CMB polarization may contain “fingerprints” of gravity waves at z=1000 and z=30ish,
2. The technology for such measurements is rapidly being brought to the field, and prospects look very good.
THE END
Epsilon vs. a
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From the NASA/NSF/DOE Task force on CMB research report, 2005
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Epsilon vs. a
From the NASA/NSF/DOE Task force on CMB research report, 2005
Reheating
Remember: kinetic term << potential term => exponential expansion.
As inflation “starts to end”:
GW Omega(f)
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Hi gang, ハハハハハハハ vis-a-vis our discussion this morning, here are approximate specs on several experiments that are in operation or being built that will search for B-modes at ell ~ 30 -> 100. ハハハハハハハ Of these, the performance estimates for BICEP (Hivon) are the most dated, followed by EBEX (? Bacigallupi?) and then QUIET (?Gorski?), which are the most recent. ハ The QUIET site goes into some detail about what effects have and have not been included in their performance estimates. ハハハハハハハ I hope to talk to Gorski today to find out what may or may not have been already done for Planck and QUIET.aBICEP20 x 40 degrees at 1 degree resolutionQUIET:20 x 20 degrees at 14 arcmin4 x 4 degrees at 3.5 arcminhttp://quiet.uchicago.edu/index.phpEBEX:20 x 30 degrees
at 8 arcminhttp://groups.physics.umn.edu/cosmology/ebex/index.htmlhttp://arxiv.org/abs/astro-ph/0501111--