K. Ganga – CMB Science and Observations 1 Rencontres du Vietnam - 2006/08/09

CMB Science and

Observations

K. Ganga

K. Ganga – CMB Science and Observations 2 Rencontres du Vietnam - 2006/08/09

The CMB● The CMB is a blackbody

at T = 2.73 K.

● The most prominent “anisotropy” in the CMB, with amplitude of about 0.1%, is due to our motion with respect to the CMB rest frame.

● Further anisotropies are at the level of 0.001% and lower (or much lower)

K. Ganga – CMB Science and Observations 3 Rencontres du Vietnam - 2006/08/09

Observerz =1000 z = infinity

Plasma

Recombination

T=2.73K

Plasma

Horizon ~1o

z =1000

Plasma

Recombination

Gravitational lensing

T=2.73K

Reionisation

Observer

The CMB again...Thanks to A. Taylor

K. Ganga – CMB Science and Observations 4 Rencontres du Vietnam - 2006/08/09

T on super-horizon scales (>1o)• Sachs-Wolfe Effect: Gravitational redshift due to

photons climbing out of potential wells,

T13

A. Taylor

K. Ganga – CMB Science and Observations 5 Rencontres du Vietnam - 2006/08/09

Acoustic Oscillations

K. Ganga – CMB Science and Observations 6 Rencontres du Vietnam - 2006/08/09

Measuring Curvature

Flat

Closed

Open

1

2

3

Acoustichorizon

(same for all)

vs tdec

J. Ruhl

B. Crill

K. Ganga – CMB Science and Observations 7 Rencontres du Vietnam - 2006/08/09

Baryons change the “effective mass”

W. Hu

K. Ganga – CMB Science and Observations 8 Rencontres du Vietnam - 2006/08/09

How Parameters are Fit

Parameters are found by making spectra for the

range of models of interestand finding which has the “best” chi-squared giventhe actual data and some

“prior” information.

Angular spectrum varies mostly with

bcdmH0,ns

K. Ganga – CMB Science and Observations 9 Rencontres du Vietnam - 2006/08/09

'Degeneracies' require other data

lpeak200 0-1/2

Simulated “Pretty flat” models

tot = 1

K. Ganga – CMB Science and Observations 10 Rencontres du Vietnam - 2006/08/09

A little help from our friends...

From: Lewis & Bridle 2002

Red: Pre-WMAP CMB data

Blue: CMB data w/ HST

Yellow: CMB data w/ HST, 2dF, BBN

K. Ganga – CMB Science and Observations 11 Rencontres du Vietnam - 2006/08/09

The CMB Temperature Power Spectrum

Archeops/ARGO/ATCA/BAM/DASI/DMR/FIRS/IAB/MAX(IMA)/OVRO/Python/QMAP/Relict/Saskatoon/South Pole/Tenerife/Toco/Viper/White Dish/...

WMAP/Acbar/BOOMERanG/CBI/VSA

K. Ganga – CMB Science and Observations 12 Rencontres du Vietnam - 2006/08/09

Quadrupole Scattering

e-

CMB polarization is caused by Thomson scattering of a local

quadrupole (Rees, 1968).

The polarized component of the

CMB must be small, as it

results from local temperature anisotropies.

K. Ganga – CMB Science and Observations 13 Rencontres du Vietnam - 2006/08/09

Polarization has been measured

Lens

IGW

DASI, CBI, BOOMERanG and CAPMAPhave all published polarization detections.

DASI

WMAP

K. Ganga – CMB Science and Observations 14 Rencontres du Vietnam - 2006/08/09

Parameters

K. Ganga – CMB Science and Observations 15 Rencontres du Vietnam - 2006/08/09

Can decompose Q & U into:E-modes (even-parity):

(or grad)

B-modes (odd-parity): (or curl)

E-modes produced by all quadrupole sources (velocity gradients and gravitational waves)

B-modes produced by gravitational waves and lensing of E-modes

The E/B Decomposition

Pure E Pure B

Wayne Hu

K. Ganga – CMB Science and Observations 16 Rencontres du Vietnam - 2006/08/09

Lensing transform E to B

● Converts E-modes to B-modes– Confusion limit to measuring the gravitational wave

component– Interesting signal in itself, probing growth of structure

from present-day to epoch of decoupling

K. Ganga – CMB Science and Observations 17 Rencontres du Vietnam - 2006/08/09

Inflation Constraints

V

Einflation

~ mpl×r¼

mpl2

2V 'V

2

1 ;

mpl2 V ' 'V

1 ;

r 12.4 ;

n 1 6 2 ;

Liddle & Lyth, 2000

K. Ganga – CMB Science and Observations 18 Rencontres du Vietnam - 2006/08/09

Predicted SpectraTT

EE

Lens

T/S=0.005

T/S=0.05

T/S=0.0005

BB

IGW

K. Ganga – CMB Science and Observations 19 Rencontres du Vietnam - 2006/08/09

Future Observations

Lawrence, C.R., Proceedings of Science (CMB2006)

K. Ganga – CMB Science and Observations 20 Rencontres du Vietnam - 2006/08/09

Sensitivity to Q or U (K s1/2)

780

250

170

HFI spec

3716225353

265825217

234127143

CMB BLIPCMB + Inst. BLIP

No of feeds per Q (or U)

Beam (arcmin)

Frequency

(GHz)

The Planck HFI

• 50 feeds in a focal plane of ~ 1kg at 100mK• Focal plane area ~ 2 square degrees• Instantaneous sky coverage per polarization-

sensitive frequency about: 0.1 square degrees

The HFI also has channels at 100, 545 and 850 GHz that are not polarization sensitive

K. Ganga – CMB Science and Observations 21 Rencontres du Vietnam - 2006/08/09

Predicted Planck Measurements

r=0.1,τ=0.17

K. Ganga – CMB Science and Observations 22 Rencontres du Vietnam - 2006/08/09

How to go deeper● Planck can detect r~0.1● Planck is ~2 times BLIP● Planck has ~10

detectors covering ~0.1 degree2 per frequency

● Planck observes ~1 yr.● In the BLIP limit,

ignoring cosmic variance, Δr~ σ2 ~(N

detectors•Time)-1

● A future mission should:– Achieve BLIP– Observe longer (~2)

● ~2 for satellites● John will discuss ground-

based– Use many more pixels

● To go much deeper, we must use arrays.

K. Ganga – CMB Science and Observations 23 Rencontres du Vietnam - 2006/08/09

Example: EPIC

J. Bock

K. Ganga – CMB Science and Observations 24 Rencontres du Vietnam - 2006/08/09

WMAP Foregrounds

74.3% of sky

K. Ganga – CMB Science and Observations 25 Rencontres du Vietnam - 2006/08/09

BOOMERanG and CBI Measurements

Montroy, et al.

Neither BOOMERanG nor CBIhave detected any BB at the levelof the EE polarization signals.This limits the foregrounds in theirregions.

K. Ganga – CMB Science and Observations 26 Rencontres du Vietnam - 2006/08/09

Fin

K. Ganga – CMB Science and Observations 27 Rencontres du Vietnam - 2006/08/09

Symmetry?

K. Ganga – CMB Science and Observations 28 Rencontres du Vietnam - 2006/08/09

WMAP: w versus k

K. Ganga – CMB Science and Observations 29 Rencontres du Vietnam - 2006/08/09

WMAP: w versus m