Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Anomalous X-ray pulsars and soft gamma-ray repeaters - the connection
  with supernova remnants   Many of the properties of anomalous X-ray pulsars (AXPs) and soft gamma-ray
repeaters (SGRs) are still a matter of much debate, as is the connection (if
any) between these two groups of sources. In cases where we can identify the
supernova remnant (SNR) associated with an AXP or SGR, the extra information
thus obtained can provide important constraints as to the nature of these
exotic objects. In this paper, I explain the criteria by which an association
between a SNR and an AXP/SGR should be judged, review the set of associations
which result, and discuss the implications provided by these associations for
the ages, environments and evolutionary pathways of the AXPs and SGRs. There
are several convincing associations between AXPs and SNRs, demonstrating that
AXPs are young neutron stars with moderate space velocities. The lack of
associations between SGRs and SNRs implies that the SGRs either represent an
older population of neutron stars than do the AXPs, or originate from more
massive progenitors.

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The categories of this paper are: hep-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: q-fin
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The categories of this paper are: patt-sol
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The categories of this paper are: stat
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The categories of this paper are: cond-mat
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The categories of this paper are: quant-ph
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The categories of this paper are: nlin
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The categories of this paper are: nucl-th
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The categories of this paper are: math
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The categories of this paper are: math-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: funct-an
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The categories of this paper are: plasm-ph
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The categories of this paper are: eess
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The categories of this paper are: econ