Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: How rapidly do neutron stars spin at birth?   We have studied the X-ray properties of ageing historical core-collapse
supernovae in nearby galaxies, using archival data from Chandra, XMM-Newton and
Swift. We found possible evidence of a young X-ray pulsar in SN 1968D and in
few other sources, but none more luminous than ~ a few 10^{37} erg/s. We
compared the observational limits to the X-ray pulsar luminosity distribution
with the results of Monte Carlo simulations for a range of birth parameters. We
conclude that a pulsar population dominated by periods <~ 40 ms at birth is
ruled out by the data.

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The categories of this paper are: comp-gas
18
The categories of this paper are: econ
37
The categories of this paper are: supr-con
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The categories of this paper are: cmp-lg
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The categories of this paper are: eess
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The categories of this paper are: quant-ph
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
0
The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci
7
The categories of this paper are: hep-th
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The categories of this paper are: patt-sol
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The categories of this paper are: plasm-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-th
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The categories of this paper are: nlin