1. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 1 N. Ponthieu (IAS) The conquest of sky polarization The upper limits era First detections Prospects Foregrounds

2. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 2 The very beginning… Penzias & Wilson, (1965), ApJL, 142, 419 free from seasonal variations (July, 1964-April, 1965). D. Barkats

3. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 3 The very beginning… Rees, (1968), ApJL, 153, L1 Already discusses the impact of reionization on the detection of polarization

4. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 4 The targets… HEMTS, Interferometers, correlators ( ≤ 150GHz) Bolometers, total power measurements ( ≥ 30GHz) Stokes Parameters Propagating electromagnetic wave

5. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 5 The targets… I, Q, U: XIX th century E,B : Seljak & Zaldarriaga, 1997

6. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 6 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: balloon Lubin, Smoot, Nanos: ground

7. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 7 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: balloon Lubin, Smoot, Nanos: ground

8. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 8 The first measurements…

9. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 9 The first measurements…

10. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 10 The first measurements…

11. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 11 The first measurements… NEW RESULTS FROM CBI AND BOOMERANG TODAY! See B. Mason’s talk See F. Piacenti’s talk

12. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 12 Temperature/Polarization cross power spectrum NEW RESULTS FROM CBI AND BOOMERANG TODAY! See B. Mason’s talk See F. Piacenti’s talk

13. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 13 There still is room for new exciting results… !

14. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 14 There still is room for new exciting results… !

15. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 15 … and fortunately, lots of people think so too + PAPPA (Sorry i couldn’t find when) Planck WMAP Maxipol QUAD BICEP 20052006 20072008 Clover 2010 Brain EBEX Ground Satellite Balloon 20092015-2020 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… QUIET PolarBear

16. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 16 Projected sensitivities BICEP EE

17. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 17 Clover SPIDER EE Unofficial, NP’s plot Projected sensitivities

18. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 18 BICEP BB Unofficial, NP’s plot Projected sensitivities

19. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 19 BB Clover Projected sensitivities Brain T/S = 0.7 T/S = 0.1 T/S = 0.01 T/S = 0.001

20. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 20 ~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 ?

21. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 21 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 ?

22. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 22 The foregrounds issue Tucci et al, astro-ph/0411567

23. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 23 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 75 Heiles 01 Fosalba et al 02 See P. Martin’s talk

24. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 24 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

25. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 25 |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

26. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 26 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) ~ 1.7 B (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

27. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 27 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

28. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 28 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

29. N. Ponthieu Polarization workshop, IAS, Orsay, 09/15/2005 29 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) ?