Component separation in CMB observations Jacques Delabrouille APC - - PowerPoint PPT Presentation
Component separation in CMB observations Jacques Delabrouille APC Paris 18 mars 2010 J. Delabrouille 1 The component separation problem SZ clusters ? Point sources Noise Galactic emission CMB Anisotropies WMAP Observation at 30 GHz 18
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Jacques Delabrouille APC Paris
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Point sources Galactic emission Noise WMAP Observation at 30 GHz SZ clusters ? CMB Anisotropies
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90 GHz 70 GHz 30 GHz 20 GHz 40 GHz
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– Morphology / shape of components – Colour of components – Independence of components – … to separate the emissions due to each individual component, and extract the information of interest about each of them…
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Delabrouille et al. MNRAS (2009) 493, vol.3, p. 835 Ghosh et al. in preparation Melin et al. submitted to A&A (arXiv/1001.0871)
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Empirical covariance matrix
everything else known scaling
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K Ka Q V W
If there were no foregrounds
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Galactic Latitude Scale
large small low
K Ka Q V W
K Ka Q V W
high
K Ka Q V W
K Ka Q V W
If there were no foregrounds
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WMAP: 11 zones Tegmark et al.: 9 zones Park et al.: 400 zones
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localised in space and in scale : spherical needlets
can decompose a map in needlets, work on the needlet coefficients, and then reconstruct a map (here ILC on needlet coefficients)
– Special handling of point sources and compact sources – Use of 100 micron map (IRIS - Miville-Deschênes & Lagache)
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All sky power spectrum
1 yr 5 yr 3 yr
Map synthetised from the filtered needlet coefficients
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All sky power spectrum
1 yr 5 yr 3 yr
Map synthetised from the filtered needlet coefficients This is not (not only) a residual
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WMAP foreground reduced Tegmark et al. ILC (3 year)
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Low galactic latitude Full sky High galactic latitude
Other maps are significantly more noisy (at least on small scales)
Delabrouille et al. MNRAS (2009) 493, vol.3, p. 835
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evolution of potential wells on CMB photons traversing (blueshift for decaying potential wells).
tracer permits to check for the effect.
LSS: many sources, good sky coverage.
flux > 10 mJy + the NILC map. They claim significance an order of magnitude better than in previous
WMAP-NVSS cross-correlation Massardi et al. arXiv:1001.1069
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– Error dominated by noise, not by foregrounds – Less noise than in individual channel maps
the CMB
have to be careful not to add more noise than we subtract CMB
that channel's resolution. Filter out residual noise using a latitude- dependent approximation of a Wiener filter.
Tuhin Ghosh, JD et al. in preparation
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– Poor resolution (13' to 60') – Poor discrimination between thermal SZ and CMB
matched filter: we look for objects of known emission law and known shape in maps containing correlated contaminants.
Melin et al. A&A (2006) 459, p. 351
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Melin et al. (2010) submitted to A&A (arXiv/1001.0871)
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Model: Lx ! M500 from Pratt et al. (2009) M500 ! Y500 from Arnaud et al. (2009)
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exploitation of CMB observations
components of interest and the scientific objectives.
put them all in a coherent frame.
instrumental noise becomes sub-dominant, and scientific objectives ever more ambitious.
– Planck : Leach et al. 2008 – Future polarisation experiments : Betoule et al. 2009