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arXiv · 1603.05976

BICEP2 / Keck Array VII: Matrix based E/B Separation applied to BICEP2 and the Keck Array

Keck Array·BICEP2 Collaborations·:·P. Ade·Z. Ahmed·R. W. Aikin·K. D. Alexander·D. Barkats·S. J. Benton·C. A. Bischoff·J. J. Bock·R. Bowens-Rubin·J. A. Brevik·I. Buder·E. Bullock·V. Buza·J. Connors·B. P. Crill·L. Duband·C. Dvorkin·J. P. Filippini·S. Fliescher·J. Grayson·M. Halpern·S. Harrison·S. R. Hildebrandt·G. C. Hilton·H. Hui·K. D. Irwin·J. Kang·K. S. Karkare·E. Karpel·J. P. Kaufman·B. G. Keating·S. Kefeli·S. A. Kernasovskiy·J. Kovac·C. L. Kuo·E. M. Leitch·M. Lueker·K. G. Megerian·T. Namikawa·C. B. Netterfield·H. T. Nguyen·R. O'Brient·R. W. IV·A. Orlando·C. Pryke·S. Richter·R. Schwarz·C. D. Sheehy·Z. K. Staniszewski·B. Steinbach·R. V. Sudiwala·G. P. Teply·K. L. Thompson·J. E. Tolan·C. Tucker·A. D. Turner·A. G. Vieregg·A. C. Weber·D. V. Wiebe·J. Willmert·C. L. Wong·W. L. K. Wu·K. W. Yoon
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Abstract

A linear polarization field on the sphere can be uniquely decomposed into an E-mode and a B-mode component. These two components are analytically defined in terms of spin-2 spherical harmonics. Maps that contain filtered modes on a partial sky can also be decomposed into E-mode and B-mode components. However, the lack of full sky information prevents orthogonally separating these components using spherical harmonics. In this paper, we present a technique for decomposing an incomplete map into E and B-mode components using E and B eigenmodes of the pixel covariance in the observed map. This method is found to orthogonally define E and B in the presence of both partial sky coverage and spatial filtering. This method has been applied to the BICEP2 and the Keck Array maps and results in reducing E to B leakage from LCDM E-modes to a level corresponding to a tensor-to-scalar ratio of $r<1\times10^{-4}$.

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Keck Array, BICEP2 Collaborations, :, P. Ade, Z. Ahmed, R. W. Aikin, K. D. Alexander, D. Barkats, S. J. Benton, C. A. Bischoff, J. J. Bock, R. Bowens-Rubin, J. A. Brevik, I. Buder, E. Bullock, V. Buza, J. Connors, B. P. Crill, L. Duband, C. Dvorkin, J. P. Filippini, S. Fliescher, J. Grayson, M. Halpern, S. Harrison, S. R. Hildebrandt, G. C. Hilton, H. Hui, K. D. Irwin, J. Kang, K. S. Karkare, E. Karpel, J. P. Kaufman, B. G. Keating, S. Kefeli, S. A. Kernasovskiy, J. Kovac, C. L. Kuo, E. M. Leitch, M. Lueker, K. G. Megerian, T. Namikawa, C. B. Netterfield, H. T. Nguyen, R. O'Brient, R. W. IV, A. Orlando, C. Pryke, S. Richter, R. Schwarz, C. D. Sheehy, Z. K. Staniszewski, B. Steinbach, R. V. Sudiwala, G. P. Teply, K. L. Thompson, J. E. Tolan, C. Tucker, A. D. Turner, A. G. Vieregg, A. C. Weber, D. V. Wiebe, J. Willmert, C. L. Wong, W. L. K. Wu, K. W. Yoon. 2016-03-18. BICEP2 / Keck Array VII: Matrix based E/B Separation applied to BICEP2 and the Keck Array. https://doi.org/10.3847/0004-637x/825/1/66

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