Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Radio Polarization from the Galactic Plane in Cygnus   We present 1420 MHz (lambda=21cm) observations of polarized emission from an
area of 117 degree square in the Galactic plane in Cygnus, covering 82 < l <
95, -3.5 < b < +5.5, a complex region where the line of sight is directed
nearly along the Local spiral arm. The angular resolution is ~ 1', and
structures as large as 45' are fully represented in the images. Polarization
features bear little resemblance to features detected in total power: while the
polarized signal arises in diffuse Galactic synchrotron emission regions, the
appearance of the polarized sky is dominated by Faraday rotation occurring in
small-scale structure in the intervening Warm Ionized Medium. There is no
concentration of polarization structure towards the Galactic plane, indicating
that both the emission and Faraday rotation occur nearby. We develop a
conceptual framework for interpretation of the observations. We can detect only
that polarized emission which has its origin closer than the polarization
horizon, at a distance d_ph; more distant polarized emission is undetectable
because of depth depolarization (differential Faraday rotation) and/or beam
depolarization (due to internal and external Faraday dispersion). d_ph depends
on the instrument used (frequency and beamwidth) as well as the direction being
studied. In our data we find that d_ph ~ 2 kpc, consistent with the
polarization features originating in the Local arm.

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The categories of this paper are: gr-qc
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The categories of this paper are: physics
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The categories of this paper are: adap-org
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The categories of this paper are: funct-an
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The categories of this paper are: hep-lat
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The categories of this paper are: plasm-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: q-fin
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The categories of this paper are: acc-phys
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The categories of this paper are: bayes-an
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The categories of this paper are: patt-sol
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The categories of this paper are: solv-int
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The categories of this paper are: econ
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The categories of this paper are: hep-th
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The categories of this paper are: dg-ga
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The categories of this paper are: cmp-lg