Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Upper Limits on X-ray Emission from Two Rotating Radio Transients   X-ray emission from the enigmatic Rotating RAdio Transients (RRATs) offers a
vital clue to understanding these objects and how they relate to the greater
neutron star population. An X-ray counterpart to J1819-1458 is known, and its
properties are similar to those of other middle-aged (0.1 Myr) neutron stars.
We have searched for X-ray emission with Chandra/ACIS at the positions of two
RRATs with arcsecond (or better) localisation, J0847-4316 and J1846-0257.
Despite deep searches (especially for J1847-0257) we did not detect any
emission with 0.3-8 keV count-rate limits of 1 counts/ks and 0.068 counts/ks,
respectively, at 3sigma confidence. Assuming thermal emission similar to that
seen from J1819-1458 (a blackbody with radius of approximately 20 km), we
derive effective temperature limits of 77 eV and 91 eV for the nominal values
of the distances and column densities to both sources, although both of those
quantities are highly uncertain and correlated. If we instead fix the
temperature of the emission (a blackbody with kT=0.14 keV), we derive
unabsorbed luminosity limits in the 0.3-8 keV range of 1e32 erg/s and 3e32
erg/s. These limits are considerably below the luminosity of J1819-1458 (4e33
erg/s), suggesting that RRATs J0847-4316 and J1846-0257 have cooled beyond the
point of visibility (plausible given the differences in characteristic age).
However, as we have not detected X-ray emission, it may also be that the
emission from RRATs J0847-4316 and J1846-0257 has a different character from
that of J1819-1458. The two non-detections may prove a counterpoint to
J1819-1458, but more detections are certainly needed before we can begin to
derive general X-ray emission properties for the RRAT populations.

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The categories of this paper are: cond-mat
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The categories of this paper are: q-bio
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The categories of this paper are: math
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The categories of this paper are: stat
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-ph
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The categories of this paper are: supr-con
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The categories of this paper are: alg-geom
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The categories of this paper are: econ
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The categories of this paper are: physics
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The categories of this paper are: nucl-ex
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The categories of this paper are: nlin
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The categories of this paper are: gr-qc
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The categories of this paper are: mtrl-th
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The categories of this paper are: cs
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The categories of this paper are: eess