Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: XMM-Newton Observations of the Extremely Low Accretion Rate Polars
  SDSSJ15531.12+551614.5 and SDSSJ132411.57+032050.5   XMM-Newton observations of the polar SDSSJ155331.12+551614.5 reveal that all
the X-ray flux emerges at energies less than 2 keV. The best fit to the
spectrum is with a thermal plasma with kT=0.8 keV plus a 20-90 ev black body,
yielding a thermal X-ray luminosity of 8-9.5E28 ergs/s. The low temperature and
X-ray luminosity, together with the lack of variation of the X-ray flux during
the observations, are all consistent with an extremely low accretion rate that
puts the system in the bombardment regime of accretion, rather than accretion
involving a standoff shock. It is likely that the observed X-rays originate
from the M dwarf secondary star, thus providing a base activity level for late
main sequence stars in close binaries. SDSSJ132411.57+032050.5 is detected by
XMM-Newton at the faint EPIC pn count rate of 0.0012 c/s, giving an upper limit
to the X-ray luminosity of 7E28 ergs/s for a distance of 300 pc, which is also
consistent with the above scenario.

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The categories of this paper are: nucl-ex
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The categories of this paper are: cs
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The categories of this paper are: stat
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The categories of this paper are: supr-con
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The categories of this paper are: q-bio
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The categories of this paper are: math-ph
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The categories of this paper are: funct-an
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The categories of this paper are: hep-ex
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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: dg-ga
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The categories of this paper are: physics
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The categories of this paper are: q-alg
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The categories of this paper are: chem-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: nlin