Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observations of the Goldreich-Kylafis effect in star-forming regions
  with XPOL at the IRAM 30m telescope   The Goldreich-Kylafis (GK) effect causes certain molecular line emission to
be weakly linearly polarized, e.g., in the presence of a magnetic field.
Compared to polarized dust emission, the GK effect has the potential to yield
additional information along the line of sight through its dependence on
velocity in the line profile. Our goal was to detect polarized molecular line
emission toward the DR21(OH), W3OH/H2O, G34.3+0.2, and UYSO1 dense molecular
cloud cores in transitions of rare CO isotopologues and CS. The feasibility of
such observations had to be established by studying the influence of polarized
sidelobes, e.g., in the presence of extended emission in the surroundings of
compact sources. The observations were carried out with the IRAM 30m telescope
employing the correlation polarimeter XPOL and using two orthogonally polarized
receivers. We produced beam maps to investigate instrumental polarization.
While in nearly all transitions toward all sources a polarized signal is found,
its degree of polarization only in one case surpasses the polarization that can
be expected due to instrumental effects. It is shown that any emission in the
polarized sidelobes of the system can produce instrumental polarization, even
if the source is unpolarized. Tentative evidence for astronomically polarized
line emission with pL<~1.5% was found in the CS(2-1) line toward G34.3+0.2.

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The categories of this paper are: hep-ex
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The categories of this paper are: cmp-lg
21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
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The categories of this paper are: math-ph
15
The categories of this paper are: nucl-ex
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The categories of this paper are: quant-ph
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The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
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The categories of this paper are: econ
34
The categories of this paper are: chem-ph
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The categories of this paper are: stat
32
The categories of this paper are: atom-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: cs