CMB & Foreground Polarisation

1. CMB & Foreground Polarisation Carlo Baccigalupi, SISSA/ISAS CMB 2003 Workshop, Minneapolis

2. What We Know What We Guess Known (Polarisation) Foregrounds Existing Data Existing Simulations Microwave Frequency Scaling Approaching from Low Frequency CMB Contamination CMB Cleaning contents E, B & TE Contamination Sky Distribution Experience The Magic New Spells Magic Limitations & Future Arts

3. Foreground Chart: Total Intensity

4. Foreground Chart: Polarisation

5. CMB & Radio Source Polarisation

6. Radio Sources: Recipe • Study polarised sources from the NVSS catalogue at 1.4 GHz

7. Radio Sources: Recipe • Study polarised sources from the NVSS catalogue at 1.4 GHz • Lookfor common sources in the GB6 catalogue at 4.85 GHz in total intensity for estimating the spectral index distribution

8. Radio Sources: Recipe • Study polarised sources from the NVSS catalogue at 1.4 GHz • Lookfor common sources in the GB6 catalogue at 4.85 GHz in total intensity for estimating the spectral index distribution • Calculate the radio polarisation degree:1GHz 2 %

9. Radio Sources: Recipe • Study polarised sources from the NVSS catalogue at 1.4 GHz • Lookfor common sources in the GB6 catalogue at 4.85 GHz in total intensity for estimating the spectral index distribution • Calculate the radio polarisation degree:1GHz 2 % • Check on higher frequencies (up to 10 GHz, Mack et al. 2002) and correct for Faraday depolarisation: 10GHz 31GHz (steep), 10GHz 1-31GHz (flat spectra)

10. Radio Sources: Recipe • Study polarised sources from the NVSS catalogue at 1.4 GHz • Lookfor common sources in the GB6 catalogue at 4.85 GHz in total intensity for estimating the spectral index distribution • Calculate the radio polarisation degree:1GHz 2 % • Check on higher frequencies (up to 10 GHz, Mack et al. 2002) and correct for Faraday depolarisation: 10GHz 31GHz (steep), 10GHz 1-31GHz (flat spectra) • Extrapolate the NVSS polarised population to the microwave band using the recipe by Toffolatti (1998) or applying the estimated spectral index distribution and correcting for steepening at 15 GHz (Taylor et al. 2001) Tucci et al. 2003, Mesa, Baccigalupi et al. A&A 2002

11. Radio Sources: CMB Contamination 30 GHz 100 GHz Tucci et al. 2003, Mesa et al. A&A 2002

12. Radio Sources: Perspects Analyse ATCA Polarised Sources at 18.5 GHz Measure Microwave Sources Polarisation Degree Check Faraday Depolarisation with Radio Band Improve CMB Contamination Estimate Investigate the Physics of the Sources Ricci et al. in preparation

13. CMB & Synchrotron Polarisation

14. Synchrotron: Giardino et al. 2002 Analyse the Haslam radio Synchrotron template assuming theoretical polarisation emission Analyse low & medium Galactic latitude data (Duncan 1997, 1999, Uyaniker 1999) Extrapolate Haslam to small angles and convolve with radio polarisation angle statistics from D97, D99, U99 Extrapolate to Microwave Build Q & U templates assuming random polarisation angle

15. Synchrotron: Tucci et al. 2000, Baccigalupi et al. 2001 Analyse low & medium Galactic latitudes data (Duncan 1997, 1999, Uyaniker 1999) Check depolarisation with known rotation measures and removing bright HII regions on the Galactic plane Take Brouw & Spoelstra (1976) as representative of the degree and sub-degree angular scales Extrapolate to Microwave as Giardino (2002) rescaling power to match Baccigalupi (2001)

16. Synchrotron: E & B CMB Contamination

17. Synchrotron: TE CMB Contamination

18. Synchrotron: Non-Rigid Frequency Scaling S, -3.2 <  < –2.5 Giardino et al. 2002

19. Synchrotron: Riddles • Are our predictions reliable? • What is the structure of the spectral index on degree and sub-degree sngular scales? • What is the statistics of the polarisation angle? • Why in Duncan et al. (1997, 1999) and Uyaniker (1999) the signal does not depend on latitude up to b=20o ?

20. Component Separation Polarisation Non-blind: Tegmark Efstathiou 1996, Bouchet & Gispert 1998, Hobson et al. 1998, Stolyarov et al. 2001 Blind: Baccigalupi et al. 2000, Delabrouille et al. 2002, Maino et al. 2002, Delabrouille, Cardoso, Patanchon 2003 Polarisation: Baccigalupi et al. 2003 Data: Barreiro et al. 2003, Maino et al. 2003

21. Experience the Magic Pixels or Modes Components d = A s + n Frequencies Components

22. Experience the Magic Pixels or Modes Components d = A ? + n Frequencies Unknown s

23. Experience the Magic Pixels or Modes d = ?? + n Frequencies Unknown s Unknown A

24. Experience the Magic Pixels or Modes d = ?? + n Frequencies Unknown s Unknown A Find s!

25. Experience the Magic LINEAR MIX

26. s = Wd = WA s + Wn d = A s + n

27. 217, 353 GHz, dust + CMBCMB recovery IN OUT

28. 217, 353 GHz, dust + CMBdust recovery IN OUT

29. Noiseless, 70 & 100 GHz Uniform Synchrotron Spectral Index Component Separation in Polarisation

30. Noiseless, 70 & 100 GHz Non-uniform Synchrotron Spectral Index Component Separation in Polarisation

31. Component Separation in Polarisation The effect of non-uniform spectral index

32. Component Separation in Polarisation Games S/N=0.5 Crash at S/N=0.2 Crash at S/N=0.5 S/N=0.5 Noisy, 70 & 100 GHz, Non-Uniform Synchrotron Spectral Index

33. Component Separation in Polarisation Is that so easy? • Simulations indicate that Planck is sensitive to T/S=30% in presence of foregrounds • Systematics: beam asymmetry, noise sky and spectral distribution. (Hu et al. 2003) • Foreground knowledge still poor

34. Conclusions • CMB Contaminations from Radio Sources: under control • CMB Contamination to E and TE: under control • CMB Contamination to B: significant on all sky • New data analysis techniques make at least conceivable to face such a contamination