N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 1 N. Ponthieu (IAS) The conquest of sky...

1N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005

N. Ponthieu (IAS)

The conquest of sky polarization

• The upper limits era

• First detections

• Prospects

• Foregrounds


The very beginning…

Penzias & Wilson, (1965), ApJL, 142, 419

free from seasonal variations (July, 1964-April, 1965).

D. Barkats


The very beginning…

Rees, (1968), ApJL, 153, L1

Already discusses the impact of reionization on the detection of polarization


The targets…

HEMTS, Interferometers, correlators ( ≤ 150GHz)

Bolometers, total power measurements ( ≥

30GHz)

Stokes Parameters

Propagating electromagnetic wave


The targets…• I, Q, U: XIXth century

• E,B : Seljak & Zaldarriaga, 1997


The upper limits era: 1965-2002

De Oliveira-Costa et al, 2002

More than 4 orders of magnitude in sensitivity gained in 37 years until the first detection by DASI (Kovac et al, 2002)

Caderni 1978: balloonLubin, Smoot, Nanos: ground


The upper limits era: 1965-2002

De Oliveira-Costa et al, 2002

More than 4 orders of magnitude in sensitivity gained in 37 years until the first detection by DASI (Kovac et al, 2002)

Courtesy D. Barkats

Caderni 1978: balloonLubin, Smoot, Nanos: ground


The first measurements…



NEW RESULTS FROM CBI AND BOOMERANG TODAY!

See B. Mason’s talk See F. Piacenti’s talk


Temperature/Polarization cross power spectrum

NEW RESULTS FROM CBI AND BOOMERANG TODAY!

See B. Mason’s talk See F. Piacenti’s talk


There still is room for new exciting results… !


… and fortunately, lots of people think so too

+ PAPPA (Sorry i couldn’t find when)

PlanckWMAP

Maxipol

QUAD

BICEP

2005 2006 2007 2008

Clover

2010

BrainEBEX

Ground

Satellite

Balloon

2009 2015-2020

CMBpol Satellite

Numbers of detectors increase, move towards matrices

Spider

See K. Ganga’s talk

See D. Barkats’ talk

See B. Jones’ talk

Mainly Bolometer experiments…

QUIETPolarBear


Projected sensitivities

BICEP

EE


Clover SPIDER

EE

Unofficial, NP’s plot



BICEP

BB

Unofficial, NP’s plot



BBClover


BrainT/S = 0.7

T/S = 0.1

T/S = 0.01

T/S = 0.001


~2012

Taking t = first light + 2 yrs data analysis, we should be on time with the WL and move on to primordial B !

OK

OK ?


• Resolution is not a true issue

• Sensitivity is critical: thousands of detectors which may lead to “large” focal planes at short wavelengths, new electronics, cryogenics…

• Control of systematics is critical

• Ultimately full sky observation

• Atmosphere makes large angular scales difficult to deal with

• Foregrounds, the ultimate limit ?

• The 2 bumps signature of B…

A satellite seems to be the only possibility to reach the limits, but there is much science to do and much to learn from earth based

experiments until then

Ongoing studies in the US (Beyond Einstein Probes) and in France at least

B mode dedicated satellite around 2020 ?


The foregrounds issue Tucci et al, astro-ph/0411567


The foregrounds issue

• The acceleration of electrons in the magnetic galactic field polarizes the synchrotron radiation

• Dust thermal radiation is polarized provided that the grains are asymetrical and aligned

Grain

B

Optical polarization

submm polarization

Lack of data on large angular scales to characterize this field

Serkowski et al 75Heiles 01Fosalba et al 02

See P. Martin’s talk


First detection of Dust polarization thermal radiation on large angular scales by Archeops (flight 2002)

• 353GHz

• Fsky ~ 20% of the sky

• 13 arcmin resolution (smoothed here for the display)

Benoit et al, 2004, AA, 424, 571

• 5% polarization in the Galactic plane

• Some clouds show 10%

• Due to confusion along the line of sight in the plane, we may expect at least as much polarization at high latitude


• |b| ≥ 5 : 4 detection on 3 < l < 8

• |b| ≥ 10: 2 detection on 3 < l < 8

• Decreasing amplitude with increasing latitude cut consistent with astrophysical origin of the signal

First estimation of the angular power spectra of dust thermal polarization on large angular scales

Ponthieu et al, 2005, AA, in press

See M. Tristram’s talk


Contamination to CMB anisotropy measurements

• Archeops results obtained @353GHz

• ~ 20% of the sky

• Need an extrapolation to lower "CMB frequencies"

• Generalization to the whole sky is uncertain

Constant index: 1.7 Equal weight 23, 33, 41, 61, 94GHz Archeops + Kp2

Toy model:

|b| ≥ 5, 100GHz:

[90, 353] GHz: I(dust) ~ 1.7B(T)Lagache 2003, Finkbeiner 2004

Ponthieu et al, 2005, AA, in press

Next data? : BLAST, PILOT

See P. Martin’s talk See JP Bernard’s talk


Contamination to CMB anisotropy measurements

Archeops (b>5deg)

Tucci et al, 0411567

Minimal assumptions on the component separation show encouraging results but

lots of uncertainties remain

See F. Stivoli’s talk

Residual dust if constant index

Residual dust if white noise uncertainty on the spectral index

See J. Aumont’s talk


Conclusions

• Significant contributions have come from the ground, balloons and satellites

• Lots of ongoing experiments are dedicating themselves to polarization and projected sensitivities are very promising

• ISM physics and cosmology benefit from eachother and will go on this way


Perspectives

• Need more data to improve our understanding of the ISM: spectral indices ? Variations of spectral indices ? Variation of alignment ? Variation of polarization degree with wavelength ? …

• Great sensitivities projections for ongoing and near future experiments, but still not clear how will the foregrounds interfere with these.

Instruments:

Sky observations:

• Need sensitivities higher by an order of magnitude (at least)

• Need developpements on detector arrays, electronics read outs, cryogenics

• Need proportionnally higher control of systematics

• Focus on high frequencies (sensitivity + instruments design) ?

N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 1 N. Ponthieu (IAS) The conquest of sky...

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