Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Subaru constraint on circular polarization in I-band emission from the
  Magnetar 4U 0142+61   We present the first imaging circular polarimetry of the anomalous X-ray
pulsar (AXP) 4U 0142+61 at optical wavelengths. The AXP is the only magnetar
that has been well studied at optical and infrared wavelengths and is known to
have a complicated broad-band spectrum over the wavelength range. The optical
polarimetric observation was carried out with the 8.2-m Subaru telescope at
I-band. From the observation, the degree of circular polarization V was
measured to be V=1.1+/-2.0%, or |V|<4.3% (90% confidence). The relatively large
uncertainty was due to the faintness of the source (I=23.4-24.0). Considering
the currently suggested models for optical emission from magnetars, our result
is not sufficiently conclusive to discriminate the models. We suggest that
because linear polarization is expected to be strong in the models, linear
polarimetry of this magnetar should be conducted.

16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
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The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-lat
15
The categories of this paper are: nucl-ex