Antenna Instrumental Polarization and its Effects on E- and B-Modes for CMBP Observations

Abstract

We analyze the instrumental polarization generated by the antenna system (optics and feed horn) due to the unpolarized sky emission. Our equations show that it is given by the convolution of the unpolarized emission map $T_b(\theta ,\varphi )$ with a sort of instrumental polarization beam $\Pi$ defined by the co- and cross-polar patterns of the antenna. This result is general, it can be applied to all antenna systems and is valid for all schemes to detect polarization, like correlation and differential polarimeters. The axisymmetric case is attractive: it generates an $E$-mode--like $\Pi$ pattern, the contamination does not depend on the scanning strategy and the instrumental polarization map does not have $B$-mode contamination, making axisymmetric systems suitable to detect the faint $B$-mode signal of the Cosmic Microwave Background Polarization. The $E$-mode of the contamination only affects the FWHM scales leaving the larger ones significantly cleaner. Our analysis is also applied to the SPOrt experiment where we find that the contamination of the $E$-mode is negligible in the $\ell$-range of interest for CMBP large angular scale investigations (multipole $\ell <10$).

9 pages, accepted for publication on A&A

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Cited by in corpus (13)

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• Systematic errors in cosmic microwave background polarization measurements
• S-band Polarization All Sky Survey (S-PASS): survey description and maps
• A radio-polarisation and rotation measure study of the Gum Nebula and its environment
• CMB Polarimetry using Correlation Receivers with the PIQUE and CAPMAP Experiments
• Sardinia Radio Telescope wide-band spectral-polarimetric observations of the galaxy cluster 3C 129
• New radio observations of anomalous microwave emission in the HII region RCW175
• Detailed study of the microwave emission of the supernova remnant 3C 396
• Spectropolarimetry with the Giant Metrewave Radio Telescope at 610 MHz: a case study of two Southern Compact Group fields
• A deconvolution map-making method for experiments with circular scanning strategies
• Systematic effects induced by a flat isotropic dielectric slab
• Effects of Thermal Fluctuations in the SPOrt Experiment
• Mitigating point-source contamination in CMB polarization: a Generalized Point Spread Function fitting approach