cmb & foreground polarisation
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CMB & CMB & Foreground Foreground PolarisationPolarisation
CMB 2003 Workshop, Minneapolis
Carlo Baccigalupi, SISSA/ISAS
What We KnowWhat We Know What We GuessWhat We Guess
CMB ContaminationCMB ContaminationCMB CleaningCMB Cleaning
Known (Polarisation) ForegroundsExisting Data
Existing SimulationsMicrowave Frequency ScalingApproaching from Low Frequency
E, B & TEContamination Sky Distribution
Experience The MagicNew SpellsMagic Limitations & Future Arts
Physics Frequency Angle Relevance
Frequency Scaling
All Sky Data
Patchy Data
Simulations
Synchrotron Synchrotron Synchrotron electrons spinning electrons spinning Galactic magnetic fieldGalactic magnetic field
< 100 GHz1o or more
Not Uniform Not Uniform Electrom Density Electrom Density
Fluctuations, Fluctuations, -2.5 -
3.2
Yes,Yes, 0.50.5 MHzMHz
FWHMFWHM1 deg1 deg
Yes,Yes, 1-3 1-3 GHzGHz
FWHMFWHM5 5 arcminarcmin
All Sky All Sky All All FrequenciesFrequencies
Free-Free BremsstrahluBremsstrahlung ng Galactic electron-ion Galactic electron-ion scatteringscattering
< 100 GHz 1o or more
Not Uniform Not Uniform Electrom Spectral Electrom Spectral
Distribution, Distribution, -2 -2.2
Yes,Yes, Traced Traced by Hby H emission emission
From All From All SkySky
All Sky All Sky All All FrequenciesFrequencies
Thermal Dust
Grey Body Grey Body by by dust grains reprocessing dust grains reprocessing UV star radiation UV star radiation
>100 GHz1o or more
Not UniformNot UniformTemperature Temperature FluctuationsFluctuations
Yes,Yes, 100 100 mm
FWHMFWHM6 6 arcminarcmin
From All From All SkySky
All Sky All Sky All All FrequenciesFrequencies
Non-Thermal Dust
SZ Inverse Inverse Compton Compton of CMB of CMB through thermal, non-through thermal, non-thermal and kinetic thermal and kinetic intracluster gasintracluster gas
Allarcmin
Uniform, Uniform, CMB CMB Rayileigh-Jeans-Wien Rayileigh-Jeans-Wien shift, dependence on shift, dependence on intracluster physicsintracluster physics
All Sky All Sky Thermal, All Thermal, All FrequenciesFrequencies
Radio Sources
See See SynchrotronSynchrotronwith different with different populations: internal populations: internal
structures, ...structures, ...
< 100 GHzarcmin
Not Uniform Not Uniform different populations: different populations:
flat, inverse, ... flat, inverse, ...
Yes,Yes, 1-20 1-20 GHzGHz
FWHMFWHMarcsecarcsec
All Sky All Sky All All FrequenciesFrequencies
Infrared Sources
See Thermal See Thermal DustDustwith different with different populations: elliptical, populations: elliptical, spirals, starburst, ...spirals, starburst, ...
>100 GHzarcmin
Not Uniform Not Uniform different populations, different populations, elliptical, spirals, starburst, cold sources, ...
Yes,Yes,12-100 12-100 mmFWHMFWHM2 2 arcminarcmin
Yes,Yes, 5-200 5-200 mmFWHMFWHM arcsec arcsec
850 850 m, 23 m, 23 arcsecarcsec
All Sky All Sky All All FrequenciesFrequencies
...
Foreground Chart: Total IntensityForeground Chart: Total Intensity
Physics Frequency Angle Relevance
Frequency Scaling
All Sky Data
Patchy Data
Simulations
Synchrotron Synchrotron Synchrotron electrons spinning electrons spinning Galactic magnetic fieldGalactic magnetic field
< 100 GHzAll Scales
Not Uniform Not Uniform Electrom Density Electrom Density
Fluctuations, Fluctuations, -2.5 -
3.2
Yes,Yes, 0.50.5 MHzMHz
FWHMFWHM1 deg1 deg
Yes,Yes, 1-3 1-3 GHzGHz
FWHMFWHM5 5 arcminarcmin
All Sky All Sky All All FrequenciesFrequencies
Free-Free BremsstrahluBremsstrahlungngGalactic electron-ion Galactic electron-ion scattering; expected scattering; expected vanishing in polarisationvanishing in polarisation
Thermal Dust
Alligned Dust Alligned Dust Grains Grains grain grain magnetic moment magnetic moment alligned with Galactic alligned with Galactic magnetic fieldmagnetic field
Non-Thermal Dust
SZ Inverse Inverse Compton Compton multiple scattering, multiple scattering, intracluster peculiar intracluster peculiar velocitiesvelocities
Allarcmin
Not Uniform, Not Uniform, CMB Rayileigh-Jeans-CMB Rayileigh-Jeans-Wien shift, dependence Wien shift, dependence on intracluster physicson intracluster physics
Radio Sources
See See Synchrotron Synchrotron with different with different populations: internal populations: internal
structures, ...structures, ...
< 100 GHzarcmin
Not Uniform Not Uniform different populations: different populations:
flat, inverse, ... flat, inverse, ...
Yes,Yes, 1-20 1-20 GHzGHz
FWHMFWHMarcsecarcsec
Infrared Sources
See Thermal See Thermal DustDustwith different with different populations, internal populations, internal structures, ...structures, ...
>100 GHzarcmin
Not Uniform Not Uniform different populations, different populations, elliptical, spirals, starburst, cold sources, ...
...
Foreground Chart: PolarisationForeground Chart: Polarisation
CMB & Radio CMB & Radio Source Source
PolarisationPolarisation
Radio Sources: RecipeRadio Sources: Recipe
• Study polarised sources from the NVSS catalogue at 1.4 GHz
Radio Sources: RecipeRadio 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: RecipeRadio 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: RecipeRadio 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 31GHz
(steep), 10GHz 1-31GHz (flat spectra)
Radio Sources: RecipeRadio Sources: Recipe
Tucci et al. 2003, Mesa, Baccigalupi et al. A&A 2002Tucci 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 31GHz (steep), 10GHz 1-31GHz (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 ContaminationRadio Sources: CMB Contamination
30 GHz
100 GHz
Tucci et al. 2003, Mesa et al. A&A 2002Tucci et al. 2003, Mesa et al. A&A 2002
Radio Sources: PerspectsRadio Sources: Perspects
Analyse ATCA Polarised Sources at 18.5 GHz
Ricci et al. in preparation 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 & CMB & Synchrotron Synchrotron PolarisationPolarisation
Synchrotron: Giardino et al. 2002Synchrotron: 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 MicrowaveBuild Q & U templates assuming random polarisation angle
Synchrotron: Synchrotron: Tucci et al. 2000, Baccigalupi et al. 2001Tucci et al. 2000, Baccigalupi et al. 2001
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 ContaminationSynchrotron: E & B CMB Contamination
Synchrotron: TE CMB ContaminationSynchrotron: TE CMB Contamination
SS, -3.2 < , -3.2 < < –2.5 < –2.5
Synchrotron: Non-Rigid Frequency Scaling Synchrotron: Non-Rigid Frequency Scaling
Giardino et al. 2002Giardino et al. 2002
Synchrotron: Riddles 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 ?
Component Component Separation Separation PolarisationPolarisation
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
Data: Barreiro et al. 2003, Maino et al. 2003
Polarisation: Baccigalupi et al. 2003
Pixels or Modes Components
Fre
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Com
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Experience the MagicExperience the Magic
Components
Fre
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Pixels or Modes
Experience the MagicExperience the Magic
Fre
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cie
s
Pixels or Modes
Experience the MagicExperience the Magic
Fre
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cie
s
Pixels or Modes
Experience the MagicExperience the Magic
Experience the MagicExperience the Magic
217, 353 GHz, dust + 217, 353 GHz, dust + CMBCMB
CMB recoveryCMB recovery
OUT
IN
OUT
IN
217, 353 GHz, dust + 217, 353 GHz, dust + CMBCMB
dust recoverydust recovery
Noiseless, 70 & 100 GHz Uniform Synchrotron Spectral Index
Component Separation in Polarisation Component Separation in Polarisation
Component Separation in Polarisation Component Separation in Polarisation Noiseless, 70 & 100 GHz Non-uniform Synchrotron Spectral Index
Component Separation in Polarisation Component Separation in Polarisation The effect of non-uniform spectral index The effect of non-uniform spectral index
Noisy, 70 & 100 GHz, Non-Uniform Synchrotron Spectral Index
S/N=0.5Crash at S/N=0.2
Crash at S/N=0.5 S/N=0.5
Component Separation in Polarisation Component Separation in Polarisation GamesGames
Component Separation in Polarisation Component Separation in Polarisation Is that so easy?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
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