the cmb and gravity waves

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--