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
2N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
The very beginning…
Penzias & Wilson, (1965), ApJL, 142, 419
free from seasonal variations (July, 1964-April, 1965).
D. Barkats
3N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
The very beginning…
Rees, (1968), ApJL, 153, L1
Already discusses the impact of reionization on the detection of polarization
4N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
The targets…
HEMTS, Interferometers, correlators ( ≤ 150GHz)
Bolometers, total power measurements ( ≥
30GHz)
Stokes Parameters
Propagating electromagnetic wave
5N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
The targets…• I, Q, U: XIXth century
• E,B : Seljak & Zaldarriaga, 1997
6N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
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
7N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
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
11N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
The first measurements…
NEW RESULTS FROM CBI AND BOOMERANG TODAY!
See B. Mason’s talk See F. Piacenti’s talk
12N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
Temperature/Polarization cross power spectrum
NEW RESULTS FROM CBI AND BOOMERANG TODAY!
See B. Mason’s talk See F. Piacenti’s talk
13N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
There still is room for new exciting results… !
14N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
There still is room for new exciting results… !
15N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
… 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
17N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
Clover SPIDER
EE
Unofficial, NP’s plot
Projected sensitivities
18N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
BICEP
BB
Unofficial, NP’s plot
Projected sensitivities
19N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
BBClover
Projected sensitivities
BrainT/S = 0.7
T/S = 0.1
T/S = 0.01
T/S = 0.001
20N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
~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 ?
21N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
• 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 ?
22N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
The foregrounds issue Tucci et al, astro-ph/0411567
23N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
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
24N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
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
25N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
• |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
26N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
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
27N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
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
28N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
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
29N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005
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) ?
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