Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: SAX J1808.4-3657 in Quiescence: A Keystone for Neutron Star Science   The accreting millisecond pulsar SAX J1808.4-3658 may be a transition object
between accreting X-ray binaries and millisecond radio pulsars. We have
constrained the thermal radiation from its surface through XMM-Newton X-ray
observations, providing strong evidence for neutrino cooling processes from the
neutron star core. We have also undertaken simultaneous X-ray and optical
(Gemini) observations, shedding light on whether the strong heating of the
companion star in quiescence may be due to X-ray irradiation, or to a radio
pulsar turning on when accretion stops.

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The categories of this paper are: gr-qc
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The categories of this paper are: atom-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-lat
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The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-th
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The categories of this paper are: bayes-an
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The categories of this paper are: chem-ph
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The categories of this paper are: q-alg
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The categories of this paper are: adap-org
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The categories of this paper are: alg-geom
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The categories of this paper are: mtrl-th
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The categories of this paper are: supr-con
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The categories of this paper are: chao-dyn