Issue |
A&A
Volume 372, Number 1, June II 2001
|
|
---|---|---|
Page(s) | 8 - 21 | |
Section | Astrophysical processes | |
DOI | https://doi.org/10.1051/0004-6361:20010414 | |
Published online | 15 June 2001 |
Power spectrum of the polarized diffuse Galactic radio emission
1
SISSA/ISAS, Via Beirut 4, 34014 Trieste, Italy
2
ITeSRE/CNR, Via P. Gobetti 101, 40129 Bologna, Italy
3
Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy
4
Osservatorio Astronomico di Trieste, Via Tiepolo 11, 34131 Trieste, Italy
Corresponding author: C. Baccigalupi, bacci@sissa.it
Received:
11
September
2000
Accepted:
16
March
2001
We have analyzed the available polarization surveys of the Galactic
emission to estimate to what extent it may be a serious hindrance to
forthcoming experiments aimed at detecting the polarized component
of Cosmic Microwave Background (CMB) anisotropies. Regions were
identified for which independent data consistently indicate that
Faraday depolarization may be small.
The power spectrum of the polarized emission, in terms of antenna
temperature, was found to be described by
K2, from arcminute to degree scales.
Data on larger angular scales (
) indicate a steeper
slope ~
. We conclude that polarized Galactic emission
is unlikely to be a serious limitation to CMB polarization measurements
at the highest frequencies of the MAP and Planck-LFI instruments,
at least for
and standard cosmological models.
The weak correlation between polarization and total power and the
low polarization degree of radio emission close to the Galactic plane
is interpreted as due to large contributions to the observed
intensity from unpolarized sources, primarily strong Hii regions,
concentrated on the Galactic plane. Thus estimates of the power
spectrum of total intensity at low Galactic latitudes are not
representative of the spatial distribution of Galactic emission
far from the plane. Both total power and polarized emissions show
highly significant deviations from a Gaussian distribution.
Key words: polarization / ISM: structure / Galaxy: general / cosmology: cosmic microwave background / radio continuum: ISM
© ESO, 2001
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