Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical and X-ray observations of candidate isolated neutron stars in
  the G315.4-2.3 SNR   G315.4-2.3 is a young Galactic supernova remnant (SNR), whose identification
as the remains of a Type-II supernova (SN) explosion has been debated for a
long time. In particular, recent multi-wavelength observations suggest that it
is the result of a Type Ia SN, based on spectroscopy of the SNR shell and the
lack of a compact stellar remnant.However, two X-ray sources, one detected by
Einstein and ROSAT (Source V) and the other by Chandra (Source N) have been
proposed as possible isolated neutron star candidates. In both cases, no clear
optical identification was available and, therefore, we performed an optical
and X-ray study to determine the nature of these two sources. Based on Chandra
astrometry, Source V is associated with a bright V~14 star, which had been
suggested based on the less accurate ROSAT position. Similarly, from VLT
archival observations, we found that Source N is associated with a relatively
bright star ($V=20.14 $). These likely identifications suggest that both X-ray
sources cannot be isolated neutron stars.

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The categories of this paper are: math
8
The categories of this paper are: hep-ex
7
The categories of this paper are: hep-th
21
The categories of this paper are: adap-org
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The categories of this paper are: comp-gas
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The categories of this paper are: bayes-an
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The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
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The categories of this paper are: q-fin
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The categories of this paper are: quant-ph
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The categories of this paper are: stat
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The categories of this paper are: nucl-th
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The categories of this paper are: atom-ph
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The categories of this paper are: econ
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The categories of this paper are: q-bio
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The categories of this paper are: funct-an