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

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

PhysicsFrequency Angle Relevance Frequency ScalingAll Sky DataPatchy DataSimulations Synchrotron Synchrotron electrons spinning Galactic magnetic field < 100 GHz 1 o or more Not Uniform Electrom Density Fluctuations, Not Uniform Electrom Density Fluctuations,   Yes, 0.5 MHz FWHM 1 deg Yes, 1-3 GHz FWHM 5 arcmin All Sky All Frequencies Free-FreeBremsstrahlung Galactic electron-ion scattering < 100 GHz 1 o or more Not Uniform Electrom Spectral Distribution, Not Uniform Electrom Spectral Distribution,  - 2  -2.2 Yes, Traced by H  emission From All Sky All Sky All Frequencies Thermal Dust Grey Body by dust grains reprocessing UV star radiation >100 GHz 1 o or more Not Uniform Temperature Fluctuations Yes, 100 m FWHM 6 arcmin From All Sky All Sky All Frequencies Non-Thermal Dust SZ Inverse Compton of CMB through thermal, non-thermal and kinetic intracluster gas All arcmin Uniform, CMB Rayileigh- Jeans-Wien shift, dependence on intracluster physics All Sky Thermal, All Frequencies Radio Sources See Synchrotron with different populations: internal structures,... < 100 GHz arcmin Not Uniform different populations: flat, inverse,... Yes, 1-20 GHz FWHM arcsec All Sky All Frequencies Infrared Sources See Thermal Dust with different populations: elliptical, spirals, starburst,... >100 GHz arcmin Not Uniform different populations, Not Uniform different populations, elliptical, spirals, starburst, cold sources,... Yes, m FWHM 2 arcmin Yes, m FWHM arcsec 850 m, 23 arcsec All Sky All Frequencies... Foreground Chart: Total Intensity

PhysicsFrequency Angle Relevance Frequency ScalingAll Sky DataPatchy DataSimulations Synchrotron Synchrotron electrons spinning Galactic magnetic field < 100 GHz All Scales Not Uniform Electrom Density Fluctuations, Not Uniform Electrom Density Fluctuations,   Yes, 0.5 MHz FWHM 1 deg Yes, 1-3 GHz FWHM 5 arcmin All Sky All Frequencies Free-FreeBremsstrahlung Galactic electron-ion scattering; expected vanishing in polarisation Thermal Dust Alligned Dust Grains grain magnetic moment alligned with Galactic magnetic field Non-Thermal Dust SZ Inverse Compton multiple scattering, intracluster peculiar velocities All arcmin Not Uniform, CMB Rayileigh-Jeans-Wien shift, dependence on intracluster physics Radio Sources See Synchrotron with different populations: internal structures,... < 100 GHz arcmin Not Uniform different populations: flat, inverse,... Yes, 1-20 GHz FWHM arcsec Infrared Sources See Thermal Dust with different populations, internal structures,... >100 GHz arcmin Not Uniform different populations, Not Uniform different populations, elliptical, spirals, starburst, cold sources, Foreground Chart: Polarisation

CMB & Radio Source Polarisation

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

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

Radio Sources: Recipe Study polarised sources from the NVSS catalogue at 1.4 GHz Look for 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 %

Radio Sources: Recipe Study polarised sources from the NVSS catalogue at 1.4 GHz Look for 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)

Radio Sources: Recipe Tucci et al. 2003, Mesa, Baccigalupi et al. A&A 2002 Study polarised sources from the NVSS catalogue at 1.4 GHz Look for 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)

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

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

CMB & Synchrotron Polarisation

Synchrotron: Giardino et al 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

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

Synchrotron: E & B CMB Contamination

Synchrotron: TE CMB Contamination

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

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=20 o ?

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

Pixels or ModesComponents Frequencies Components Experience the Magic

Components Frequencies Pixels or Modes Experience the Magic

Frequencies Pixels or Modes Experience the Magic

Frequencies Pixels or Modes Experience the Magic

217, 353 GHz, dust + CMB CMB recovery OUTIN

OUTIN 217, 353 GHz, dust + CMB dust recovery

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

Noiseless, 70 & 100 GHz Non-uniform Synchrotron Spectral Index

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

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

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

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