statistical anisotropy
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2019 ◽  
Vol 490 (3) ◽  
pp. 3404-3413
Author(s):  
Majd Ghrear ◽  
Emory F Bunn ◽  
Dagoberto Contreras ◽  
Douglas Scott

ABSTRACT In order to better analyse the polarization of the cosmic microwave background (CMB), which is dominated by emission from our Galaxy, we need tools that can detect residual foregrounds in cleaned CMB maps. Galactic foregrounds introduce statistical anisotropy and directionality to the polarization pseudo-vectors of the CMB, which can be investigated by using the $\mathcal {D}$ statistic of Bunn and Scott. This statistic is rapidly computable and capable of investigating a broad range of data products for directionality. We demonstrate the application of this statistic to detecting foregrounds in polarization maps by analysing the uncleaned Planck 2018 frequency maps. For the Planck 2018 CMB maps, we find no evidence for residual foreground contamination. In order to examine the sensitivity of the $\mathcal {D}$ statistic, we add a varying fraction of the polarized thermal dust and synchrotron foreground maps to the CMB maps and show the per cent-level foreground contamination that would be detected with 95 per cent confidence. We also demonstrate application of the $\mathcal {D}$ statistic to another data product by analysing the gradient of the minimum-variance CMB lensing potential map (i.e. the deflection angle) for directionality. We find no excess directionality in the lensing potential map when compared to the simulations provided by the Planck Collaboration.


2018 ◽  
Vol 98 (8) ◽  
Author(s):  
Takashi Hiramatsu ◽  
Shuichiro Yokoyama ◽  
Tomohiro Fujita ◽  
Ippei Obata

2018 ◽  
Vol 98 (4) ◽  
Author(s):  
Gabriele Franciolini ◽  
Alex Kehagias ◽  
Antonio Riotto ◽  
Maresuke Shiraishi

2018 ◽  
Vol 479 (4) ◽  
pp. 5577-5595 ◽  
Author(s):  
Oliver H E Philcox ◽  
Blake D Sherwin ◽  
Alexander van Engelen

2018 ◽  
Vol 97 (2) ◽  
Author(s):  
Nicola Bartolo ◽  
Alex Kehagias ◽  
Michele Liguori ◽  
Antonio Riotto ◽  
Maresuke Shiraishi ◽  
...  

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