Issue |
A&A
Volume 420, Number 2, June III 2004
|
|
---|---|---|
Page(s) | 437 - 445 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20035601 | |
Published online | 28 May 2004 |
Antenna instrumental polarization and its effects on E- and B-modes for CMBP observations
1
IASF/CNR Bologna, via Gobetti 101, 40129 Bologna, Italy
2
IEIIT/CNR Torino, C.so Duca degli Abruzzi 24, 10129 Torino, Italy
Corresponding author: E. Carretti, carretti@bo.iasf.cnr.it
Received:
30
October
2003
Accepted:
18
March
2004
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 with a sort of instrumental polarization beam
Π 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
Π 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
-range of
interest for CMBP large angular scale
investigations (multipole
).
Key words: polarization / cosmology: cosmic microwave background / instrumentation: polarimeters / methods: data analysis
© ESO, 2004
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