Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the nature of the intermittent pulsar PSR B1931+24   PSR B1931+24 is the first intermittent radio pulsar discovered to date,
characterized by a 0.8 s pulsation which turns on and off quasi-periodically
every ~35 days, with a duty cycle of ~10%. We present here X-ray and optical
observations of PSR B1931+24 performed with the Chandra X-ray Observatory and
Isaac Newton Telescope, respectively. Simultaneous monitoring from the Jodrell
Bank Observatory showed that this intermittent pulsar was in the radio-on phase
during our observations. We do not find any X-ray or optical counterpart to PSR
B1931+24 translating into an upper limit of ~2x10^{31} erg/s on the X-ray
luminosity, and of g' > 22.6 on the optical magnitude. If the pulsar is
isolated, these limits cannot constrain the dim X-ray and optical emission
expected for a pulsar of that age (~1.6 Myr). We discuss the possibility that
the quasi-periodic intermittent behavior of PSR B1931+24 is due to the presence
of a low mass companion star or gaseous planet, tight with the pulsar in an
eccentric orbit. In order to constrain the parameters of this putative binary
system we re-analysed the pulsar radio timing residuals and we found that (if
indeed hosted in a binary system), PSR B1931+24 should have a very low mass
companion and an orbit of low inclination.

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The categories of this paper are: comp-gas
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The categories of this paper are: funct-an
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The categories of this paper are: econ
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The categories of this paper are: q-alg
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The categories of this paper are: q-fin
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The categories of this paper are: solv-int
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The categories of this paper are: math
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The categories of this paper are: hep-th
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The categories of this paper are: hep-lat
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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-th
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The categories of this paper are: alg-geom
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The categories of this paper are: adap-org
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The categories of this paper are: stat
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The categories of this paper are: chem-ph