August 31, 2006 2nd Sino-French workshop

B Polarization Measurementof the CMB

at the Concordia Station (Dôme C)

Yannick Giraud-Héraud(APC - Paris)

August 31, 2006 2nd Sino-French workshop

OUTLINE

• reminder of CMB polarization parameters• challenges for CMB polarization measurements• observationnal status and forthcoming observations• BRAIN: an interferometer at Dôme C (Antartica) for measuring B mode polarization of the CMB

August 31, 2006 2nd Sino-French workshop

• Total intensity:

• Linear polarization:

I = <|Ex|2> + <|Ey|2>

Q = <|Ex|2> - <|Ey|2>

U = <|Ex’ |2> - <|Ey’ |2>

Ex(t)

Ey(t) x’

y’

Stokes Parameters

WMAP3 23 GHz

August 31, 2006 2nd Sino-French workshop

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

August 31, 2006 2nd Sino-French workshop

Uses of CMB Polarization

• Tighter constraints on cosmological parameters• Gravity waves from inflation

• nature of gravity• test of inflation• energy scale• Planck-era physics?

• Lensing reconstruction• constraints on Dark Energy• neutrino mass measurement

August 31, 2006 2nd Sino-French workshop

CMB observables as probe for inflation

- r : ratio between the amplitude of tensor/scalar power spectrum

- nS, nT spectral indices of scalar and tensor power spectrum

- power spectrum of type B polarized anisotropies

access to primordial gravitational waves

WMAP3 alone: r<0.55 (95% C.L.) (GW<2.0 10-12)

(based on temperature power spectrum)

WMAP3 alone: ns=0.987+0.019-.0.037 (no running contribution)

August 31, 2006 2nd Sino-French workshopC. Rosset

( )17.0=τ

1.0=r

41055.6 −×=r€

E I ~ 2 ×1016GeV

GeVEI15107.5~ ×

€

r ≡T 2

S2∝

E I

M pl

⎛

⎝ ⎜ ⎜

⎞

⎠ ⎟ ⎟

4

What can we get from CMB polarization measurements?

August 31, 2006 2nd Sino-French workshopC. Rosset

Weak lensingE mode B mode

νm

énergie noire

€

τ =0.17( )

What can we get from CMB polarization measurements?

August 31, 2006 2nd Sino-French workshop

Polarization has been measured

Lens

IGW

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

DASI

WMAP

August 31, 2006 2nd Sino-French workshop

Planck

• Full sky survey– CMB anisotropies

• Temperature and polarization• Resolution: 5’• Sensitivity: ∆T/T = 2.10-6

– Foregrounds

• 15 times more sensitive than WMAP

• Planck will be the ultimate experiment– for T up to l 2000,– for E up to l 1000 …

• … but will be able to detect B mode only if r is closed to its actual upper limit.

~100µK RMS

Mode E~4µK RMS

Mode B~300nK RMS

(Hu et al. 2002)

Planck, for a 14 months survey:

r=0.7

August 31, 2006 2nd Sino-French workshop

Planck Polarization(Planck Blue Book)

E spectra

B spectra

August 31, 2006 2nd Sino-French workshop

Which objectives for the CMB physics after Planck

- high-angular resolution Sunyaev-Zel’dovich effect

- increase the number of detectors to measure the polarized anisotropies polarisées with an optimization of the optical scheme to fight the systematic effects

Probe of the inflation epoch and of the Large Scale Structures

August 31, 2006 2nd Sino-French workshop

Sensitivity of forthcoming observations

(Task Force on Cosmic Microwave Background Research - July 2005)

E1 : 1000 detectors ; 1 year ; 6’ ; 4 % of the skyE2 : 1000 detectors ; 1 year ; 1’ ; 0,4 % of the skyE3 : 1000 detectors ; 1 year ; 30’ ; 100 % of the sky

E1

E2

E3

August 31, 2006 2nd Sino-French workshop

Long term effort

BICEPQUaD

ClOVEREBEXPolarBearQUIET

CMBpol (NASA & ESA)SAMPAN (CNES)

~2005

~2008-2010

>2015

eV 03.0=νm(Kaplinghat et al. 2003)

Gravitational wavesGravitational waves

(Ken Ganga 2004)

QUaD, BICEP (2005-2008)

CLOVER, EBEX, POLARBEAR, BRAIN (2008-2011)

SAMPAN, CMBPOL(> 2018)

August 31, 2006 2nd Sino-French workshop

French-ItalianConcordia Station at Dôme C

August 31, 2006 2nd Sino-French workshop

Concordia Station at Dôme C

• 3 traverses (12-15 days) from Dumont d’Urville to

Dôme C (1100 km) every Summer (3x150 tonnes)

4 hours flight from Terra Nova Bay with Twin Otter• first Winter season from February 2006 to

September 2006 with 13 overwinterers• Excellent atmospheric transmission all over the year

winter averagepwv = 250 m

Data South Pole

No measurement during the Winter Season in mm wavelenghts: site testing needed

Dome A

Zhongshang

Dumont d’Urville

August 31, 2006 2nd Sino-French workshop

Optical Depth for3 sites :- Chajnantor (ALMA)- Pôle Sud- Mauna Kea

Transmission = eτ

Peterson et al. 0211134

1 year Dôme C = 2 years South Pole =5 years Atacama Plateau

(e-1/e-3 = 7,4)

August 31, 2006 2nd Sino-French workshop

Polarization of the atmosphere

• Zeeman Effect on the oxygene lines

• Circular Polarization– Estimation:

100µK CMB

(Modes B: <300nK RMS)

August 31, 2006 2nd Sino-French workshop

Sky Coverage

Projection of the foregrounds at 150 GHz (centered on the South Pole)

The 2 circles are at declinations -40° et -80° (Dôme C at -74°30’)

The upper region between the 2 circles is a potential zone for observation

Ability to observe always the same part of the sky

Scanning direction changes with time

August 31, 2006 2nd Sino-French workshop

The instrument at Concordia (January 2006)

BRAIN

Collaboration France-Italy-UK(Rome, Milan, Cardiff, APC, CSNSM, CESR, IAS, LISIF)

August 31, 2006 2nd Sino-French workshop

BRAIN: a prototype of bolometric interferometer

Why an interferometer ?

• sensitivity similar to a photometer

• direct measurement of the Stokes parameters (e.g. Cl)

• differential measurement

reduction of atmospheric noise

• simplified optical set-up (no mirror)

reduction of systematic effects (atmosphere, far side lobes, …)

Horns

Ortho-Mode Transducers

Phase shifters

Beam combiners

Bolometers

August 31, 2006 2nd Sino-French workshop

1) Pathfinder

Objectives:• automatic monitoring of the cryogenic system (300 mK) during the Winter season• achieve the control of the experiment from Europe which implies satellite telemetry (INMARSAT, IRIDIUM, …)• measurement of the atmospheric noise during the Winter at 150 GHz (intensity and polarization)

2) Validation of the interferometry approach in the millimetric domain using bolometers

• at room temperature in the laboratory• at Dôme C with 6 baselines

BRAIN : 2 STEPS - 2006-2008

August 31, 2006 2nd Sino-French workshop (January 2006)

August 31, 2006 2nd Sino-French workshop

BRAIN 2: looking for primordial B modes

• Dôme C (Antartica)

• 3 telescopes at 90, 150 and 220 GHz

• 3 interferometers of 16x16 horns with bolometric read-out

– 50 < l < 150

• Starting in 2009?

R=0.1

R=0.01

R=0.001

(Clément Cressiot, 2006)

August 31, 2006 2nd Sino-French workshop

August 31, 2006 2nd Sino-French workshop

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.

August 31, 2006 2nd Sino-French workshop

Optique froide (Cardiff)

Prototype:

Cornets Archeops:

August 31, 2006 2nd Sino-French workshop

Optique froide (Cardiff)

Prototype:

Cornets Archeops:

August 31, 2006 2nd Sino-French workshop

Déphaseur à 4K

• Responsabilité APC-LISIF• Déphaseur diélectrique• Actionneur piézoélectrique• Statut:

– Simulations réalisées

– Design figée

– En réalisation au BE

– Tests en septembre 2005

August 31, 2006 2nd Sino-French workshop

Sensitivity comparison between total power array of bolometers and bolometric interferometer

Total # of photons:A: area main dish: solid angle of single pixel

⋅AN Total # of photons:A’: area input horn’: solid angle of input horn

''⋅AN

sensitivity is equal when ''⋅=⋅ ANAN